Petrology, Mineralogy, and Geochemistry of the Goldlund Gold Deposit, Northwestern Ontario Steven D

University of North Dakota UND Scholarly Commons

Theses and Dissertations Theses, Dissertations, and Senior Projects

1986 Petrology, mineralogy, and geochemistry of the Goldlund Gold Deposit, Northwestern Ontario Steven D. Giddings University of North Dakota

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Recommended Citation Giddings, Steven D., "Petrology, mineralogy, and geochemistry of the Goldlund Gold Deposit, Northwestern Ontario" (1986). Theses and Dissertations. 107. https://commons.und.edu/theses/107

This Thesis is brought to you for free and open access by the Theses, Dissertations, and Senior Projects at UND Scholarly Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of UND Scholarly Commons. For more information, please contact [email protected]. PETROLOGY, MINERALOGY, AND GEOCHEMISTRY OF THE GOLDLUND GOLD DEPOSIT, NORTHWESTERN ONTARIO

by Steven D. Giddings Bachelor of Arts, St. Cloud State University, 1982 I

I I

!i f A Thesis Submitted to the Graduate Faculty

'\ of the § University of North Dakota in partial fulfillment of the requirements for the degree of Master of Science

Grand· Forks, North Dakota

December 1986 This thesis submitted by Steven D. Giddings in partial fulfillment of the requirements for the degree of Master of Science from the University of North Dakota has been read by the Faculty Advisory Committee under whom the work has been done, and is hereby approved.

This thesis meets the standards for appearance and conforms to the style and format requirements of the Graduate School of the University of North Dakota, and is hereby approved.

/0 pv/t:t, e Graduate School

ii 561,15:1 Permission

Title Petrology, Mineralogy, and Geochemistry of the Goldlund Gold Deposit, Northwestern Ontario Department ~~==~------Geolo Degree Master of Science

In presenting this thesis in partial fulfillment of the requirements for a graduate degree from the University of North Dakota, I agree that the Library of this University shall make it freely available for inspection. I further agree that permission for extensive copying for scholarly purposes may be granted by the professor who supervised my thesis work or, in his absence, by the Chairman of the Department or the Dean of the Graduate School. It is understood that ahy copying or publication or other use of this thesis or part thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and the University of North Dakota in any scholarly use which may be made of any material in my thesis.

Signature ~ Duwi ~ Date K>/t0/86

iii TABLE OF CONTENTS

LIST OF ILLUSTRATIONS • vi

LIST OF TABLES, • • ix ACKNOWLEDGMENTS ... xi ABSTRACT ...... xiii CHAPTER 1. INTRODUCTION . . l 1.1 Location . • • • . . l 1.2 Purpose and Scope • 1 1.3 Geologic Setting • . . 4 1.4 Previous Work and General Geology • 10

CHAPTER 2. PETROGRAPHY AND GEOCHEMISTRY OF METAMORP~IC AND IGNEOUS ROCKS • • • • • • • . . • , 18

2.1 Keewatin Lavas and Associated Metasedimentary Rocks • • • • .. • • .. • • • 18 2.2 Monzodiorite •.• ·-• •••••• 29 2.3 Albitized Tonalite Dikes ..• 37 2.4 Granitic and Quartz Monzonitic Rock Types 65

CHAPTER 3. MINERALOGY AND GEOCHEMISTRY OF ORE ZONE il AND THE OPEN PIT . ·. . • . • • • • • 91

3.1 Vein Mineralogy. • . . • • • . • • • •. 91 3.2 Chemical and Mineralogical Changes Associated With Alteration ••.••• 91 3.3 Description of Ore Minerals and Associated Minerals •••. . . 118 CHAPTER 4, INTERPRETATION AND DISCUSSION . . 134 4.1 General Geology ••••.••• 134 4.2 Comparisons and Petrogenesis of the Various Intrusive Rock Types • • • • • • • • • 137 4.3 Alteration ...... 150 4.4 Mineral Paragenesis of Ore-bearing and Associated Minerals ..••••••.•• 157 4.5 Generalized Model of Gold Deposition for the Goldlund Deposit ••••••.••..•.• 166 CHAPTER 5. CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE STUDY •••••.•• , 172

5.1 Conclusions • • . •.•.•• 172 5.2 Recommendations for Future Study 174

iv APPENDICES • • ...... 176 APPENDIX A. Sample Locations • • • 177 APPENDIX B. Methods and Procedures 187 APPENDIX C. Whole Rock Chemical Analyses of Samples Used in Alteration Studies 199 APPENDIX D. Chemical Analyses and CIPW Normative Mineralogy of Miscellaneous Rock Types. 206

REFERENCES CITED •••••••••••••.••••• 211

V LIST OF ILLUSTRATIONS

Figure • • .. • 3 1. Location Map of the Study. Areas . . . . 2. Geologic Setting and General Geology of the Study Areas . . • • • • . • • . • . • • . • . .• 6

3. Stratigraphic Section and Age Relationships of the Sioux Lookout Area. • • • • • • • • 9

4. Geologic Map of the Eastern Study Area • 15

5. Geologic Map of the Western Study Area . . 17 6. Photomicrograph of Pillowed Basalt (Sample EA-3) • 24

7. Photomicrograph of Feathered Amphibolite (Sample MC-7) • • • • • • • • • 24

8. Field Photograph of Spherulit1c Lava ••• • 27

9. Photomicrograph of Spherulitic Lava (Sample Z3-l). 27

10. Triangular QAP and AFM Plots of Monzodiorites 36

11. Slab Photograph of Dark-Phase, Albitized Tonalite (Sample EA-28) • • • • • • . • ...... 42

12. Photomicrograph of Dark-Phase, Albitized Tonalite (Sample EA-19) ••••.• ...... 42

13. Variability of Intergrowths in Dark- and Light- Phase, Albitized Tonalites • • . • • • • • • • 47

14. Slab Photograph of Light-Phase, Albitized Tonalite (Sample EA-14) •.••••••• . .. . . 50

15. Photomicrograph of Light-Phase, Albitized Tonalite (Sample EA-33) .••.••••• 50

16. Triangular QAP and AFM Plots of the Dark- and Light-Phase, Albitized Tonalites •.•••.• . . 62

17. Triangular Q-Ab-Or and K-Na-Ca Plots of the Dark- and Light-Phase, Albitized Tonalites • • • • • . 64

18. Slab Photograph of.Quartz Porphyry (Sample MR-4) 72 19. Photomicrograph of Quartz Porphyry (Sample MR-5) 72

vi 20. Slab Photograph of Quartz Monzonite (Sample OA-7) • ...... • • . . . . . • 72 21. Photomicrograph of Quartz Monzonite (Sample OA-2) . • • . . . . • . • ...... 72 22. Slab Photograph of Quartz-Feldspar Porphyry (Sample EA-24) ...... • . . . . . 79 23. Photomicrograph of Quartz-Feldspar Porphyry (Sample EA-10) . . • • . . . . • . • . • . . . . 79 24. Slab photograph of crossecho Stock Granite (Sample CLS-6) . . • ...... • . • 79 25. Photomicrograph of Crossecho Stock Granite (Sample CLS-6) . • • • ...... • 79 26. Triangular QAP and AFM Plots of the Quartz Mon- zonite Stock, Quartz Porphyry Dikes, Quartz- Feldspar Porphyries, ·and Crossecho Stock . • . . . 88 27. Triangular Q-Ab-Or and K-Na-Ca Plots of the Quartz Monzonite Stock, Quartz Porphyry Dikes, Quartz- Feldspar Porphyries, and Crossecho Stock. • • 90 28. Slab Photograph of Quartz Vein and Associated Alteration Halo . • • • • • • • • • • • 94 29. Slab Photograph of Zoned Alteration Around a Quartz Vein ...... •.... 94 30. Photomicrograph of Visibly Altered, Light-Phase, Albitized Tonalite (Sample EA-13) •• • 94

31. Alteration Profile From Stope 1-13E • • 98

32. Alteration Profile From the Open Pit • 100

33. Alteration Profile From the Open Pit • 102

34. Alteration Profile From Stope 1-05CW. • 104 35. Alteration Profiles of Sulfur and Arsenic Con centration Changes for Samples From the Open Pit and Stope l-05CW • .....•••.•••.••• 106 36. Alteration Profiles of Cobalt, Lead, Copper, Barium, and Rubidium Concentration Changes for Samples From Stope 1-13E and the Open Pit •• 108

vii 3.7. Composition-Volume Diagram and Graph for Unaltered Average and Visible Alteration of Stope l-13E •••••••••••••. . • 112

38. Composition-Volume Graphs for Stope 1-13E and the Open Pit. • • . . • • • • • • • • • • • • 115

39. Composition-Volume Graphs for Stope 1-05CW and the Open Pit. . . • . • . • • • • • • • 117

40. Backscattered Electron Images of Mineral to Mineral Relationships • ...... 130 41. Backscattered Electron Images of Mineral to Mineral Relationships ...... 132 42. AFM, K-Na-Ca, and Q-Ab-Or Plots of the Intrusive Rock Types .. • . • • • • ...... • • .. • . 14 0

43. Observed Fractionation Trends on Rb-Sr, Ti-Zr, Nb-Zr, and Y-Zr Diagrams. • • • • • • •••. 143

44. Silica Variation (Harker) Diagram of the Crossecho Stock- Quartz-Feldspar Porphyry Quartz Monzonite Stock Rock Series •.• • • • 14 6

45. Simplified Schematic Summary of Chemical and Mineralogical Changes Associated With Alteration. 153

46. Generalized Paragenetic Sequence of Ore-bearing Minerals, Including Xenotime, in the Goldlund Mine Veins. • • • ••.• ...... 159 47. Relationships in the Synthetic Au-Ag-Te System 165

48. Sample Locations, Eastern Study Area 180 49, Sample Locations, Western Study Area . . . 182 so. Sample Locations, East Extension (Closeup) 184 51. Sample Locations, Ore Zone lf2 (Closeup) 186

viii LIST OF TABLES

Table

1. List of Precambrian Geologic Units, Crossecho Lake Area . • • . . . • . • • . • •. • . • 12

2. Microprobe Analyses of Minerals and Matrix Compositions in Keewatin Lavas •••• 21

3 • Microprobe Analyses of Matrix and Bulk Com- positions, Spherulitic Lavas and Meta- sedimentary Rocks ...... 28 4. Microprobe Analyses of Minerals in Monzo- diorites ...... 33 5. Chemical Analyses and CIPW Normative Mineralogy of Monzodiorites •••• . . . . . 34 6. Modal Analyses of Dark-Phase, Albitized Tonalite Dikes ....••....•.. . • . . . 40 7. Microprobe Analyses of Minerals in Dark Phase, Albi ti zed Tonal i tes • . . • • ...... 43 8. Modal Analyses of Light-Phase, Albitized Tonalite Dikes ..•••..•••.•. . . . . 51 9. Microprobe Analyses of Minerals in Light- Phase, Albitized Tonalites • • . . • •• 52

10. Chemical Analyses and CIPW Normative Mineralogy of Dark-Phase, Albitized Tonalite Dikes . • • . 57

11. Chemical Analyses and CIPW Normative Mineralogy of Light-Phase, Albitized Tonalite Dikes. . 59

12. Petrographic Summary of Granitic and Quartz Monzonitic Rock Types ••.••••••. 68

13. Microprobe Analyses of Minerals in Quartz Porphyries ...... • ...... 69 14. Microprobe Analyses of Minerals in Quartz Mom~onite Stock . . . • ...... 73 15. Microprobe Analyses of Minerals in Feldspar and Quartz-Feldspa-r Porphyries ...... 75

ix 16. Microprobe Analyses of Minerals in Crossecho Stock ...... 80 17. Chemical Analyses and CIPW Normative Mineralogy of Quartz Monzonite Stock 82 18. Chemical Analyses and CIPW Normative Mineralogy of Quartz-Feldspar Porphyries . • • . • • • • • 83

19. Chemical Analyses and CIPW Normative Mineralogy of Crossecho Stock . . . 84 20. Chemical Composition of Petzite . . . 124

21. Chemical Composition of Altaite • . • 126 22. Chemical Composition of Calaverite 127 23. Chemical Composition of Native Gold . 133 24. List of Underground Sample Locations . 178 25. Scanning Electron Microscope/Electron Probe Microanalyzer Precision and Accuracy ••• • 190 26. Major Element Precision 195 27. Major Element Accuracies 196 28. Whole Rock Chemical Analyses of Samples Used in Alteration Studies •••. • 201 29. Chemical Analyses and CIPW Normative Mineralogy of Miscellaneous Rock Types ..•.•• 208

X ACKNOWLEDGEMENTS

With much appreciation I would like to acknowledge the numerous people and organizations that have made this study possible. I am greatly indebted to my advisory committee,

Professor Frank Karner, Professor Dexter Perkins, and

Professor Don Halvorson for their invalua.ble insight, suggestions, assistance, and critical review of the manuscript.

I would like to thank Sigma Xi, the University of

North Dakota Graduate School, the Mining and Mineral

Resources Research Institute of North Dakota, and the

Ontario Ministry of Natural Resources for financial assis tance. I would especially like to thank Don Janes of the Ontario Ministry of Natural Resources for his invaluable help and assistance.

I am grateful to Goldlund Mines Limited whose permission made this study possible, and for room and board and both surface and underground access while on site.

I would also like to thank the Natural Materials

Analytical Laboratory at the University of North Dakota and in particular Dr. Robert Stevenson, R. Al Larsen, and Tim

Huber for their laboratory assistance. Special thanks are extended to Louie J. Cabri for contribution of gold-silver telluride standards used in microprobe studies, and the

Ontario Ministry of Natural Resources for CO2 and H20 determinations.

xi To my family, and especially my parents, I extend my deepest thanks for their love, encouragement, and support. Finally, I thank my wife Lynn Marie whose love, patience, encouragement, and suppo,rt gave me the strength to overcome the difficult times.

xii ABSTRACT

The Goldlund Mine is located in the Wabigoon Sub

province of the Canadian Shield. Although the mine has

been open sporadically since the late 1930's, little is

known about the geochemistry and petrography of the

deposit. The purpose of this study was to use petro

graphic, geochemical, and physical data to document and

better understand the host rock, alteration, and mineral

ization of the deposit, and to develop a generalized model of formation.

Results showed that the host rocks of the gold mineral

ization are albitized tonalite dikes. Gold, in native form and in gold-silver tellurides, occurs in quartz veins and in adjacent zones of metasomatic alteration within the tonalite.

Two texturally different phases of albitized tonalite exist. A light, fine- to medium-grained phase, which contains the majority of gold mineralization, is surrounded by a dark, fine-grained border phase.

Distinct alteration zones are present around quartz veins which fill tension fractures in the tonalite dikes. In addition to zones of visible alteration near the veins, cryptic zones farther from the veins were recog

nized. Five alteration types recognized include: carbon atization, albitization, pyritization, desilicification, and dehydration. Geochemical data shows that carbon dioxide, sodium, calcium, and manganese were added to the • tonalite from the veins, while iron, water, magnesium, and

xiii potassium were added to the veins from the tonalite. corresponding mineralogical data suggests the breakdown of chlorite, biotite, and albite/quartz intergrowths, with formation of secondary carbonate, albite, pyrite, and vein quartz.

A three-stage paragenetic sequence was recognized: an early, high temperature stage, a middle, dominantly sulfide stage, and a late, low temperature gold and telluride stage.

Native gold, petzite, calavarite, and altaite were deposited in the late, low temperature stage.

AFM, Q-Ab-Or, K-Na-Ca, Rb-Sr, Ti-Zr, Nb-Zr, and Y-Zr diagrams permit development of petrogenetic models for the intrusive rock types. The albitized tonalite dikes appear to have formed from a different magma source than the granite of the Crossecho Stock, the quartz monzonite stock, and the quartz-feldspar porphyries. The albitized tonalite dikes were probably derived by partial melting of amphibo lite and are syn-volcanic in age. The quartz-feldspar porphyries and quartz monzonite stock appear to be differentiated fractions of the magma of the Crossecho

Stock and were intruded into the supracrustal• assemblage during active plutonism of the Kenoran Orogeny.

The Crossecho Stock and other late intrusives appear to have acted as concentrating agents, supplying heat and volatiles which mobilized gold from the surrounding volcanic rocks with subsequent deposition in tension fractures of the albitized tonalite dikes.

xiv CHAPTER 1

INTRODUCTION

1.1 LOCATION

The Goldlund gold deposit is the best known of several gold occurrences in Echo Township and is located approxi mately 42km southwest of Sioux Lookout and 32km northeast of Dinorwic, Ontario along provincial highway 72 {Figure

1). An 8 square-kilometer area was studied which includes selected claims of Goldlund Mines Limited, Camreco In corporated, and the northeastern exposure of the Crossecho

Stock. The claims are all located east of Crossecho Lake •

The Crossecho Stock is located south and • west of Crossecho

Lake.

1.2 PURPOSE AND SCOPE

The purpose of this study was to examine petrologic, geochemical, and field data in order to better understand the Crossecho Lake area gold deposits. Webb (1948) reported on the geology of the gold deposits. This study expands on Webb's work by applying geochemical and petro logical techniques not previously .used. X-ray fluorescence

(XRF), H20-C02 determination, scanning electron microscopy

(SEM)/ electron probe microanalysis (EPMA), and petro graphic microscope methods were used extensively in this study. The main objectives of the study include:

1) To examine the albitized tonalite host rock and deter-

1 2

i f f I

•

Figure 1: Location map of the study areas. HUDSON BAY

0 -Stf JAMES BAY N

RED PICKLE CROW LA\E • WINNIPEG • NIPIGON . . w I-z :::, TIMMINS• 00 r KIRKLAND LAKE• I I

LJYN SIOUX ~ (Ejl OKOUT .I [\J

TO 0 5KM 4

mine its petrographic and geochemical characteristics.

2) To compare the geochemistry and petrography of the

intrusive rock types with the host rock to examine

relationships and test models of ore genesis.

3J To examine the gold bearing minerals, mineral

associations, and gold concentrations to determine

mineral paragenesis.

4) To determine the types of hydrothermal alterations

associated with the gold-bearing veins and to

examine qualitatively the geochemical changes

associated with the alteration.

5) To combine the above objectives to determine a general

model of gold deposition. l. 3 GEOLOGIC SETTING

The Superior Province of Canada is composed of distinct lithologic, structural, and metamorphic sub provinces. In the western part of the province these subprovinces are linear, east-west trending, alternating, sedimentary-plutonic and volcanic-plutonic belts (Condie,

1981). The Goldlund gold deposit is located within the

Wabigoon volcanic-plutonic subprovince (Figure 2).

The Wabigoon subprovince extends from Manitoba in the west to the Phanerozoic cover west of James Bay in the east including assemblages of metavolcanic, volcaniclastic, minor metasedimentary, and intrusive granitic rocks of ' Archean age (Mackasey and others, 1974). The rocks of the subprovince have undergone greenschist to middle amphib- •

I I [

{

Figure 2: Geologic setting and general geology of the study areas. Modified from Trowell and others (1980). Rectangles indicate the specific areas of study.

!l.~!$~W!J.t~ BERENS JAMES BAY RIVER ·,

UCHI I" . ER ... ENGLISH RI L---- ..II.; , WABIGOON 1~: 1111; I~'..... ,ii''t~ 11;~,: 11::.llf I lli~,1!11 I ·:;\ ,,,'· I lit~:, --.__.---../ "·11 ;:11: r!I! ' l,~!I

rnE!ls GRANITOIO ROCKS

f\~14 MINNITAKI GROUP

t\m13ABRAM GROUP

~ INT.-FELSIC ~ ZMETAVOLCANICS

CENTRAL VOLCANIC D 1 BELT SOUTHERN VOLCANIC D 0BELT

0 . 5KM 7 olite facies metamorphism. Hart and Davis (1969) reported an age of 2700-2750 million years for the Wabigoon and!

Quetico subprovinces. Davis and others (1980), studying the Savant-Crow Lake area, reported a range from 2678-2789 million years.

The Goldlund deposit is located within the Sioux

Lookout sub-area of the Savant Lake to Crow Lake meta volcanic-metasedimentary belt (Trowell and others, 1980).

The sub-area is divided into five lithostratigraphic units.

Figure 2 shows the location of the study area and the units found in the area. Figures 3A and 3B show the general relationships between the different units.

The Southern Volcanic Belt consists primarily of intermediate to mafic flows and felsic to intermediate pyroclastics (Trowell and others, 1980).

The Northern Volcanic Belt consists of a south facing metavolcanic sequence of mafic flows (Trowell and others,

1980). The flows are divided into high-iron and high magnesium tholeiitic basalts. Also included are intrusive equivalents. The Patara Metasedimentary Group is an upper metasedimentary-metavolcanic sequence within the Northern

Volcanic Belt. It consists of volcanogenic metasedimentary rocks, felsic to intermediate pyroclastic rocks, volcanic breccias and agglomerates, associated conglomerates, and hypabyssal subvolcanic quartz porphyry and felsites.

The Ament Bay Formation consists of granitoid-clast conglomerates and arkoses. The overlying Daredevil 8

Figure 3: A. Stratigraphic section of the Sioux Lookout area. Modified from Turner and Walker (1973, p.822).

B. Age relationships of rock stratigraphic units of the Sioux Lookout area. (From Trowell and others, 1980, p.8). I A...... - - - "'ID m m <.)z 12 '"•'"~m m <( <.) - - - Maaalve (,n) and pltlowed flowa, .., ~ , - with lull and agglomerate al leaal 0 - - - partly aubaqueoua. > 10 ... m <( a: •• ..z m 8 <.)"' ~ ·~

...., Palara Sediments z"'a: Ill . :c"' <.) ..a:z - 2 0 <( zg m 0 > I Thou,and Melara

B. SIOUX LOOKOUT AREA

Central Volcanic Ball

-Abram and Mlnnllakl .. Groups L.:.... aandatone. mudatone Abram. Pa1ara, and _ Mlnnllakl Conglomeratn0 rV: 0~~:::: ~:1::::.

Southern Volcanic Bait I 10

Formation consists of turbidites, ash flows, felsic to

intermediate tuffs, and agglomerates. The south facing

Little Vermilion Formation consists of sediment-clast

conglomerates and wacke siltstone.

The Central Volcanic Belt consists of felsic to mafic

metavolcanic flows, pyroclastics, and other volcanogenic

sediments. The belt has been intruded by quartz-feldspar

porphyry and trondhjemitic subvolcanic plutons similiar to

those intruding the Patara Group (Trowell and others,

1980).

The Minnitaki Group is a metasedimentary sequence

consisting of arkose, wacke-siltstone, and granitoid-clast

conglomerates (Trowell and others, 1980). Turner and

Walker (1973) proposed that the Minnitaki Group was a young

metasedimentary sequence while Johnston (1972) concluded

that it is a folded equivalent of the Abram Group.

1.4 PREVIOUS WORK AND GENERAL GEOLOGY

Previous Work

Previous geologic work has dealt with Goldlund Mine's,

formerly Lunward and Newlund Mine's, ore zones and sur

rounding rocks. Gold was discovered in the late 1930's and

the mine has been open sporadically ever since. Recently

it was closed in the spring of 1985. Hurst (1932)

published a report on the general geology of the Sioux

Lookout area, and Webb (1948) conducted studies on the mine

area. 11

Chisholm (1951) briefly reported on the granodiorite host rock as well as the alteration and mineralization of the Newlund Mine. Chisholm concluded that the grano diorite of the Villbona Gold Mines Limited property just to the northeast of the Newlund property was most likely an extension of the dike and sill systems that crosscut the

Newlund property.

Armstrong (1951) described the rock units of Echo

Township including those of the Crossecho Lake area and produced a list of geologic rock units for Echo Township

(Table 1). He named the host rock of the Goldlund Mine a gray biotite granodiorite. Frohberg (1952) wrote an un published mine report which described the rock units, ore zones, and economic potential of the mine and modified

Armstrong's list of geologic rock units for the mine area

(Table 1) •

Very little recent work has been done on the area.

Skinner (1969) published an overview of the Sioux Lookout area geology. Blackburn and Janes (1983) grouped the

Goldlund deposit under the heading of deposits in cross fractures in lavas, tuffs, and intrusive rock types.

Most recently Brown (1985) reported 2- to 3-phase, CO2- rich inclusions in quartz from the Goldlund Mine.

General Geology

A summary of the rock units of the area as interpreted by various authors is given in Table 1. Figures 4 and 5 s~ow the two specific areas of study and their geology. 12

TABLE 1 LIST OF PRECAMBRIAN GEOLOGIC UNITS, CROSSECHO LAKE AREA

Armstrong (1951) Frohberg {1952)

Precambrian: quartz-feldspar porphyry, late granodiorite quartz porphyry

Algoman: quartz-feldspar feldspar porphyry porphyry dikes and sills lamprophyre quartz porphyry granodiorite dikes and sills (Newlund main dike) pink biotite basic diorite, diorite granite, grano diorite grey biotite granodiorite INTRUSIVE CONTACT INTRUSIVE CONTACT

Pre-Algoman: quartz porphyry INTRUSIVE CONTACT

Abram: Daredevil Sediments

Keewatin: Thunder Lake Intermediate to Zealand Sediments, basic sills, basic Brown ridge to acid lavas and Volcanics pyroclastics 13

The areas consist of a south-facing band of Keewatin volcanics that are predominantly lavas. The volcanic sequence is fault bounded to the north by the Little

Vermilion Fault. The fault separates the Keewatin volcanics from the Daredevil Sediments of the Abram Group to the north (Armstrong, 1951). To the south, the volcanics are bounded by a zone of acid to intermediate pyroclastics. The volcanic-sediment package has a regional c... l!,,,1, litt:11< strike of N60°E with dips from 80° to 90° to the southeast t:k. (Webb, 1948). Armstrong (1951) concluded that the Keewatin rocks of the area are the northern limb of a large syn

cline. He also suggested that minor folding may have taken 1:,, ,· :i 11:l place in the major structure, based on the variable strikes 'C.il~:! ,pltc:,t ~Llll>i . and dips of local iron formation units.

The Keewatin volcanics are cut by numerous Algoman intrusives. The most important is the main dike of ore zone #1. This albitized tonalite, which has been termed a granodiorite by Webb (1948), Chisholm (1951), and Arm strong (1951), serves as the main host rock for gold mineralization. The dike has been fractured, intruded by quartz-pyrite-gold veins, and has been affected by sodium metasomatism (Blackburn and Janes, 1983). Similiar dike rocks have been traced along a 15km arc parallel to the main faulting direction (Blackburn and Janes, 1983).

Gold has been found in crosscutting veins and associ ated alteration .haloes within the albitized tonalite and also within other rock types of the area. 14

Figure 4: Simplified geologic map of the eastern study area. Modified from Armstrong (1951).

- The main albitized tonalite dike extends to the southwest, running through the far west zone, although it does not outcrop on the surface.

Circled numbers represent ore zones.

' ;' ; f ''\

..... -.. .,,-.....0. .. -.. Q ...I ._... N >, -... "'Q. ""0 ... 00.

0 Figure 5: Simplified geologic map of the western study area. Modified from Armstrong (1951). /"',, ,.. ~ ,..,. ...~~-..(}, ,, ,..,J.,"' ,,,,.,,If": • ~/ • ". ' ...... ,, . . . . ( 0

0 o.s.

GRANITE CHAPTER 2

PETROGRAPHY AND GEOCHEMISTRY OF METAMORPHIC AND IGNEOUS ROCKS

2.1 KEEWATIN LAVAS AND ASSOCIATED METASEDIMENTARY ROCKS

General

The Keewatin volcanics and associated metasedimentary rocks of the Central Volcanic Belt include: basaltic lavas and flows, associated pyroclastic agglomerates, breccias and tuffs, and assorted meta-arkoses and quartzites.

Massive and pillowed basaltic lavas are very common.

The lavas border the ore zones and are also found along the northeast periphery of the Crossecho Stock. Locally the lavas are sheared and resemble chlorite schists. Two spherulitic lava horizons are found within the study areas.

One extends from the quartz monzonite stock northwest of

Goldlund's shaft, to just south of ore zone #2. The second extends from near the quartz porphyry apophysis, south of ore zones il and i5 to,Crossecho Lake (Figure 4).

Armstrong (1951) suggested the use of the spherulitic lavas as horizon markers.

Metasedimentary rock units occur intercalated within the various lava types and are minor in abundance.

Petrography

Three texturally different lavas were observed in addition to the metasedimentary rock types. Microprobe

18 1? analyses of minerals and matrix compositions of the

Keewatin lavas and bulk compositions of the associated metasedimentary rocks are given in Tables 2 and 3.

Pillowed and massive basalt

Both pillowed and massive basalts are a dark green to blue-gray color on fresh surfaces and a light gray to light green on weathered surfaces. Along the northern border of the east extension, a pillow horizon grades into a massive basalt over a short distance. The pillows are commonly elongate with up to a 6:1 width to height ratio. Selvages are poorly-defined. Vesicles are conspicuous and are con centrated towards the tops of the pillows. Carbonate and quartz stringers and lenses are common in both lavas.

The pillowed basalts are seriate porphyritic with a fine-grained to microcrystalline matrix (Figure 6). Matrix constituents include: quartz, carbonate, chlorite, plagio clase, magnetite, ilmenite, pyrite, and ferro-hornblende.

Chlorite blades are commonly aligned within the matrix.

Ferro-hornblende (Hawthorne, 1983), and both individual and compound quartz grains are the most common phenocryst minerals. Euhedral to subhedral bladed ferro hornblende grains are up to 2.5mm in length. The blades display light green to blue-green pleochroism. Rhombohe dral ferro-hornblende displays light yellow to forest green pleochroism and well developed cleavage, The grains are generally subhedral and'less than 1.0mm in size. An average composition of the microcrystalline matrix is given 20

in Table 2.

The massive basalts were divided into 2 distinct types based on thin section observations. The first is a fine grained to microcrystalline aphyric basalt with minor ferro-hornblende; the second is a coarser-grained amphibole-rich basalt grading to amphibolite and containing abundant, sheaflike, ferro-hornblende.

Mineral constituents of the aphyric basalt include: albite, quartz, chlorite, carbonate, biotite, muscovite, magnetite, ilmenite, ferro-hornblende, and epidote. Sub hedral ferro-hornblende up to 0.4mm in length, subhedral to anhedral magnetite up to 0.5mm in length, anhedral quartz up to 1.0mm in length, and bladed ferro-hornblende up to

1.0mm in length are set in a microcrystalline matrix con sisting of chlorite, carbonate, quartz, and feldspar.

Local subparallel alignment of chlorite and Carlsbad- and albite-twinned plagioclase produce a pilotaxitic texture.

An average composition of the matrix is given in Table 2.

The amphibole-rich basalt/amphibolite is allotrio morphic to hypidiomorphic granular and ranges from fine- to medium-grained. The fabric varies from an interlocking mass of Carlsbad- and albite-twinned plagioclase, sheaflike calcic amphibole, and quartz (amphibole-rich basalt), to an interlocking mass of sheaflike ferro-hornblende (amphib olite) (Figure 7). Epidote is common in small amounts in all sections as is interstitial carbonate and quartz.

Sheaflike ferro-hornblende masses range up to 3.0mm in 21

TABLE 2

MICROPROBE ANALYSES OF MINERALS AND MATRIX COMPOSITIONS IN KEEWATIN LAVAS

SAMPLE EA-3 EA-3# Z2-19 Z2-19 Z2-19 MR-7 Ferro- Average Epidote Chlorite Ferro- Albite Hblnd Matrix Hblnd

SiO:t 46.28 54.51 36.95 24.76 41.56 68.26 Al203 10.62 12.71 22.06 20.39 15.47 18.66 FeO* 18.28 10.40 12.45 29.21 23.87 0.28 MgO 9.89 5.09 o.oo 11. 22 4.59 o.oo. cao 12.17 4.92 23.50 0.07 11.80 0.22 Na20 0.98 3.09 0.00 0.00 1.24 11.25 K20 0.35 0.55 0.14 0.08 0.55 0 .13 Ti02 0.32 1.40 0.17 0.11 0.28 o.oo P205 o.oo 0.07 o.oo o.oo 0.00 0.00 MnO 0.34 0.14 0.24 0,25 0.32 0.11 ClO 0.03 0.03 o.oo 0.14 0.00 0.00 S03 0.00 0.08 o.oo 0.09 o.oo o.oo Total 99.26 92.99 95.51 86.32 99.68 98.91

Number of Ions@

Si 6.81 19.18 2.99 2.72 6.28 3.03 Al 1.84 5.26 2.10 2.64 2.76 0.97 Fe2+ 2.25 0.05 -.- 2.69 3.02 -.- Fe3+ -.- -.- 0.84 -.- 0.01 Mg 2.17 2.69 1. 84 1.03 Ca 1. 92 1.86 2.03 0.01 1.91 0.01 Na 0.28 2.11 -.- 0.36 0.97 K 0.07 0.25 0.01 0.01 0.11 0.01 Ti 0.04 0.37 0.01 0.01 0.03 p 0.02 -.- -.- -.- -.- Mn 0.04 0.02 0.02 0.04 -.- Cl -.- 0.01 -.- -.- s -.- 0.02 -.- -.- -.- -.- 0 22.00 64.60 11. 95 10.00 22.00 8.03 OH 2.00 -.- 1.00 8.00 2.00 -.- Key: * Total Fe as FeO, # Area Scan 1000 by 1000 microns

@ See Appendix B, Section 2 for procedure used in normalization.

-.- less than 0.005 or not used in normalization.

Sample EA-3 is a pillowed basalt, while samples Z2-19 and MR-7 are aphyric basalts. 22

TABLE 2

(continued)

SAMPLE MR-7 MR-7# Z3-5 Z3-5 MC-8 MC-8 Magnetite Average Albite Ferro- Ilmenite Ferro- Matrix Hblnd Mn-rich Hblnd

SiOz 0 .19 50.44· 67.47 49.28 0.51 46.47 Al203 0.31 13.79 19.13 6.43 0.10 11.01 FeO* 92.90 13.77 0.15 16.66 45.98 19.19 MgO 0.10 3.34 0.00 13.46 0.28 9.28 cao 0.15 6.35 0.65 11. 30 0.28 12.56 NazO o.oo 3.59 10.75 0.19 0.00 0.86 K20 0.00 0.15 0.09 0.35 o.oo 0.42 Ti02 0.17 1.31 0.00 0.12 48.88 0.32 Pz05 0.00 0.13 0.00 o.oo 0.00 0.00 MnO 0.10 0.14 0.07 0.34 2.12 0.31 ClO 0.11 0.06 0.00 0.03 o.oo 0.00 S03 0.00 0.05 0.00 0.00 o.oo o.oo Total 94.03 93.12 98.31 98.16 98.15 100.42

Number of Ions@

Si 0.01 18.09 3.02 7.22 0.02 6.78 Al 0.01 5.83 1.01 1.11 0.01 1.89 Fe2 + 0.99 4.13 2.04 0.88 2.34 Fe3+ 1. 97 0.01 0.09 -.- Mg 0.01 1.80 -.- 2.94 0.01 2.02 Ca 0.01 2.45 0.03 1.77 0.01 1.96 Na 2.49 0.93 0.05 -.- 0.24 K -.- 0.08 0.01 0.07 -.- 0.08 Ti 0.36 -.- 0.01 0.93 0.04 p -.- 0.04 -.- -.- -.- Mn 0.05 0.04 0.05 0.04 Cl 0.03 -.- -.- s 0.01 -.- -.- -.- -.- 0 4.00 64.20 8.07 22.00 3.00 22.00 OH 2.00 -.- 2.00

Key: * Total Fe as FeO, # Area Scan 1000 by 1000 microns @ See Appendix B, Section 2 for procedure used in normalization.

-.- less than 0.005 or not used in normalization.

Sample MR-7 is an aphyric basalt, sample Z3-5 is an amph.-rich basalt, and sample MC-8 is an amphibolite. 23

Figure 6: Photomicrograph of pillowed basalt (Sample EA- 3). Note the bladed and rhombohedral ferro hornblende in a fine-grained matrix of plagio clase, chlorite, carbonate, quartz, ferro hornblende, and assorted opaque minerals. Bar scale represents 1.0mm.

Figure 7: Photomicrograph of feathered amphibolite (Sample MC-7). The arnphibolite consists of interlocking sheaflike ferro-hornblende grains with minor plagioclase. Bar scale represents 0.25mm.

diameter while subhedral albite laths range up to 3.0mm in

length. Opaque minerals include magnetite, pyrite, and Mn

bearing ilmenite (Table 2). Minor amounts of chlorite and

biotite are also present.

Spherulitic Lavas

The spherulitic lavas are holocrystalline and fine

grained to microcrystalline. Color ranges from a dark gray

to greenish black on fresh surfaces to a light gray on weathered surfaces. The lavas are easily identified in the

field due to the knobby texture produced by weathering

(Figure 8). The spherules are elongate, ranging from 2.0

to 15.0mm in long dimension. Webb (1948) and Frohberg

(1952) concluded that the spherulitic lava horizon adjacent

to ore zone #3 was albitized by solutions from the tona

lite dike of the zone.

The spherulitic lavas consist of fine-grained quartz

spherules, with concentrations of chlorite, biotite, quartz, carbonate, albite, muscovite, and magnetite forming

the peripherial matrix {Figure 9). Euhedral to subhedral magnetite commonly occurs in the microcrystalline matrix and also occurs with quartz in the spherules. Area scans of a spherule and the peripheral matrix show dramatic changes in composition related to the mineralogical differ ences described above (Table 3). The spherules are some

times poorly-defined because of the gradational decrease in grain size from the center to the margin adjacent to the microcrystalline matrix. The original composition of the 26

Figure 8: Field photograph of spherulitic lava. Knobby texture is produced by weathering. Length of pen is approximately 15cm.

Figure 9: Photomicrograph of spherulitic lava (Sample Z3-l). Quartz-replaced spherulite with chlorite, biotite, carbonate, quartz, and magnetite forming the peripheral matrix. Bar scale represents 1.0mm.

TABLE 3

MICROPROBE ANALYSES OF MATRIX AND BULK COMPOSITIONS, SPHERULITIC LAVAS AND METASEDIMENTARY ROCKS

SAMPLE llMC-2 #MC-2 llUG-30A IIOA-10 IIZ2-10 JIZ2-10 Spherule Matrix Average Average Bulk Bulk Bulk Comp. Bulk Bulk Comp. Comp. Comp. Comp. Comp.

Si02 83.35 56.86 72.44 75.51 59.85 64.84 Al203 9.69 16.07 11.17 10.37 14.14 15.04 FeO* 1.05 15.34 3. 97 3.47 6.76 7.10 MgO 0.00 3.35 1.09 0.46 1.86 1.56 cao 2.21 1. 93 1. 92 1.62 5.19 1.40 Na2o 5.13 5.09 3.33 3.29 2.09 1.30 K20 0.26 1.04 1. 73 1.52 4.54 5.12 Ti02 0.59 0.81 0.20 0.77 0.85 2.37 P205 0.00 0.00 o.oo 0.10 o.oo 0.61 MnO 0.08 0.21 0.15 0.04 0 .14 0.23 ClO 0.08 0.04 0. 19 0.10 0.11 0.10 S03 0.06 0.00 1.18 0.00 0.11 o.oo Total 102.50 10.0. 74 97.37 97.25 95.64 99.67

Atom Percent

Si 28.46 20.78 24.84 25.80 21.16 23.10 Al 3.89 6.91 4.51 4.17 5.88 6.30 Fe 0.30 4.67 1.14 · 0. 99 1.99 2.11 Mg 0.00 1. 84 0.57 0.24 0.99 0.84 Ca 0.81 0.76 0.71 0.60 1.97 0.54 Na 3.39 3.60 2.22 2.18 1. 43 0.90 K 0.11 0.49 0.76 0.67 2.05 2.33 Ti 0.15 0.22 0.05 0.20 0.23 0.63 p o.oo 0.00 o.oo 0.03 0.00 0.18 Mn 0.03 0.07 0.04 0.01 0.04 0.07 Cl 0.03 0.02 0.08 0.04 0.05 0.04 s 0.02 0.00 0.31 0.00 0.03 o.oo 0 62.81 60.64 64.80 65.09 64.18 62.96

Key: * Total Fe as FeO, i Area Scan 1000 by 1000 Microns .Abbreviation used: Comp.- Composition.

Sample MC-2 is a spherulitic lava, samples UG-30A and OA-10 are quartzites, and sample Z2-10 is a bedded quartzite. 29 lava is unknown, but original spherulites appear to have been replaced by quartz.

Metasedimentary Rock Types A variety of intercalated metasedimentary rock types are found associated with the lavas. They include mainly bedded and non-bedded quartzites. Microprobe bulk com positions of various metasedimentary rock samples are given in Table 3. Along the southern boundary of ore zone #2, a fine grained bedded quartzite has been exposed by trenching. The quartzite is cut by a quartz-feldspar porphyry dike. In the east extension xenoliths of a similiar quartzite are found within a quartz-feldspar porphyry dike. The rock consists of very fine- to fine-grained quartz along with carbonate, chlorite, biotite, altered feldspar, and muscovite. Minor constituents include assorted opaques and euhedral to subhedral prismatic and hexagonal tourmaline crystals. Lenses of quartz and carbonate produce a flaser texture with concentrations of biotite, chlorite, and opaques producing streaks and laminae. Lenses of carbon ate are sometimes more numerous than lenses of fine-grained quartz.

2.2 MONZODIORITE

General The oldest intrusive rock of the mine area is monzo dioritic and has been described as a basic diorite by 30

Frohberg (1952). It occurs sporadically along the footwall of the main albitized tonalite dike of the 200 foot level and outcrops on the surface in the east extension. The contact between the main albitized tonalite dike and the monzodiorite is poorly defined. Frohberg (1952) suggested an intrusive origin for the monzodiorites of the mine area, based on their relationship to the local flows and frag mental rock units. Some chemical exchange has taken place between the monzodiorites and the albitized tonalite dikes but otherwise they appear unrelated. The monzodiorite ranges in width from a few meters up to approximately 10m (Frohberg, 1952).

Petrography The monzodiorite is allotriomorphic granular, fine- to medium-grained, and occasionally has distinct schistosity. The color ranges from dark gray to black on fresh surfaces, to a light greenish gray on weathered surfaces. Mineral constituents include: albite, quartz, chlorite, biotite, ferro-hornblende, carbonate, epidote, magnetite, ilmenite, and apatite. Microprobe analyses for various minerals are presented in Table 4. Subhedral to anhedral albite grains, generally <1.5mm, display both Carlsbad and albite twinning and are altered to saussurite. The analyzed grains ranged in composition from An 3. 3 to An 6.7 • Less commonly the albite forms an intergrowth with quartz where the quartz appears to have 31 invaded and replaced the albite.

Quartz is present in both compound and anhedral individual grains. The grains are generally less than

1.5mm and some contain numerous fluid inclusions. Euhedral apatite rods less than 0.1mm in length are common inclusions in both quartz and quartz-albite intergrowths.

Chlorite and biotite are common constituents of the monzodiorite. Biotite is very abundant in some sections and nearly absent in others. Biotite is commonly partially altered to chlorite. Chlorite appears as both a secondary mineral and as discrete primary blades.

Ferro-hornblende is present as subhedral to anhedral, commonly poikilitic, grains typically containing chlorite, carbonate, quartz, and feldspar. The grains are generally less than 1.0mm in size and display striking light yellow to forest green pleochroism. Some grains h3-ve rhombic outlines and distinct cleavage. A minor amount of bladed ferro-hornblende is present in one section. The blades are less than 1.0mm in length and have distinct light yellow to blue-green pleochroism.

Carbonate is a common constituent in all sections.

The carbonate is interstitial or is an alteration product of plagioclase. Epidote occurs as distinct subhedral grains less than 0.5mm in diameter. Epidote is also present in minor amounts as an alteration product of plagioclase. Both magnetite and ilmenite are found in the monzo- 32 diorite. Ilmenite occurs in subhedral blades and in anhedral grains. The ilmenite commonly has a high manganese content (Table 4). Magnetite is present in sub hedral to anhedral grains. Inclusions of other minerals within both opaques are common. Magnetite also occurs as small inclusions within various minerals.

Chemistry

Major and trace element chemical analyses and CIPW normative mineralogy for three samples of monzodiorite are given in Table 5. The monzodiorites have the lowest Si02 content (47.65%-55.15%) of the intrusive rock types examined. The rocks are peraluminous with the Al203 con tent varying only slightly from 13.42% to 13.67%. The monzodiorites are easily distinguished from the other rock types due to their high FeO content (8.93%-14.49%). compared to the other rock types of the area the rocks have higher concentrations of Co {up to 98.Sppm) and Zn (up to

91.9ppm), slightly higher concentrations of As (up to

65.4ppm) and S (up to 444.2ppm), with lower concentrations of Cu and Ni.

The monzodiorites plot in the tholeiitic field on an

AFM plot, and two of the samples fall within the monzo diorite field of the QAP plot with the third falling in the granite field (Figure 10). The monzodiorites are similiar in composition to the average for diabase (LeMaitre, 1976b, no.26), and normal tholeiitic basalt (Nockolds, 1954, Table

7, no. 7) • 33

TABLE 4

MICROPROBE ANALYSES OF MINERALS IN MONZODIORITES

SAMPLE EA-25 EA-25 UG-21 UG-21 Albite Ferro Epidote Ilmenite Hornblende

Si02 68.33 43.89 38.43 0.37 Al203 19.49 12.46 22.78 0.35 FeO* 0.06 19.27 12.25 44.82 MgO 0.00 8.37 o.oo 0.19 cao 0.69 12.07 23. 65 0.13 Na20 11.17 1. 42 0 .oo o.oo K20 0.07 0.37 0.08 o.oo Ti02 0.07 0.38 0.24 49.95 Pz05 o.oo o.oo o.oo 0.00 MnO 0.11 0.20 0.24 2. 79 ClO o.oo 0.00 0.11 0.00 S03 o.oo 0.00 0.09 o.oo Total 99.99 98.43 97.87 98.60

Number of Ions@

Si 3.00 6.57 3.03 0.01 Al 1.01 2.20 2.12 0.01 Fe 2 -I 2.41 0.88 Fe3+ -.- -.- 0.80 0.07 Mg 1.87 -.- 0.01 Ca 0.03 1.94 2.00 0.01 Na 0.95 0.41 -.- -.- K 0.01 0.07 0.01 -.- Ti -.- 0.04 0.01 0.95 p -.- Mn 0.03 0.02 0.06 0 8.03 22.00 11. 97 3.00 OH 2.00 1.00

Key: * Total Fe as FeO @ See Appendix B, Section 2 for procedure used in normalization.

less than 0.005 or not used in normalization. 34

TABLE 5

CHEMICAL ANALYSIS AND CIPW NORMATIVE MINERALOGY OF MONZODIORITES

SAMPLE UG-9 UG-13 UG-15

Si02 55.15 47.65 52.96 Alz03 13.61 13.67 13.42 Fe203 1.48 2 .41 2.27 FeO 8.93 14.49 13.64 MgO 2.43 4.92 3.38 cao 6.39 6.89 6.63 Na20 2,17 2.67 2.96 K20 2.06 0.74 0.20 Ti02 1.17 2.30 2, 39 Pz05 0.53 0.28 0.45 MnO 0 .17 0.26 0.27 Total 94.09 96.28 98.57

Cr 26.1 15.4 8.7 Co 53.6 98.5 89.7 Ni 9.4 0.6 0.0 Cu 7.9 7.9 11.0 Zn 82.9 91,9 74.9 Rb 46.1 17.9 7.5 Sr 80.7 61. 3 117.8 y 35.0 30.9 51.7 Zr 238.3 88.7 141.5 Nb 15.6 10.4 11.5 Ba 808.7 199.9 71.0 Pb 11.5 9.2 8.1 As 62.4 60.8 65.4 s 444.2 193.3 404.3

QZ 15.04 0.28 9.71 OR 12.94 4.54 1.20 AB 19.51 23.47 25. 41 AN 22.65 24.02 23.07 WO o.oo 0.00 0.00 DI 6.26 8.07 6.23 HY 17.65 30.78 25.39 co 0.00 0.00 o.oo MT 2.28 3.62 3.33 IL 2.36 4 .54 4.60 AP 1. 31 0.68 1.06 Figure 10: Triangular QAP and AFM plots for monzodiorites.

A. Q=normative quartz, A=Or(Or+Ab+An)/(Or+An), and P=An(Or+Ab+An)/(Or+An), where An=normative anorthite, Or=normative orthoclase, and Ab= normative albite {after LeMaitre, 1976a). Classification after Streckeisen (1976).

B. A=Na20+K20, F=Fe0+0.8998{Fez03), M=MgO, all in weight percent. The diagram is divided into tholeiitic (Th) and calc-alkaline (C) fields after Irvine and Barager (1971). A. a

GRANITE

8. F 37

2.3 ALBITIZED TONALITE DIKES

General

The albitized tonalite dikes are the host rocks for the ore of the mine area. The term granodiorite was given to the dikes of the area, but the lack of potassium feld spar and the low KzO content of the rock type suggest that the rock is a tonalite rather than a granodiorite. The dikes make up ore zones 11, 2, 3, and 5. Gold mineral ization occurs in quartz-carbonate-pyrite veins, which fill tension fractures within the dikes, as well as in the alteration haloes adjacent to the veins.

Two phases of albitized tonalite are present on the

Goldlund Mine property, a light, fine- to medium-grained phase and a darker, fine-grained phase. The two phases are slightly different texturally and mineralogically. The contact between the two phases varies, usually with one phase grading into the other. In rare locations the contact is sharp and well-defined. Frohberg (1952} report ed that dikes of the darker phase cut the lighter phase and concluded that it was the result of more than one magmatic surge. The dark phase is usually found on the footwalls and occasionally the hanging walls of the dikes, with the lighter phase towards the center. Frohberg (1952} cited the unconformable relationship of the dikes. with the surrounding volcanics as well as local interfingering of the albitized tonalites as evidence against a selective replacement origin of the albitized tonalites. The dikes 38 are cut by feldspar and quartz-feldspar porphyry dikes and other minor intrusives and are also sheared in distinct zones. Four dikes oriented subparallel to regional strike make up the ore zones mentioned above. The main dike extends from west of the Camreco shaft, through ore zone

41, the open pit, and through the east extension (Figure

4). This dike and others continue to the northeast, but thick overburden prevents correlation (Chisholm, 1951).

The dike strikes N60°E to N65°E and dips 80° to 95° to the south (Webb, 1948; Chisholm, 1951). In the far-west zone the dike strikes N87°W dipping 67° south. The dike ranges in width from 10m to 50m and has been mined underground and on the surface. In the east extension both light and dark phases are present, with the dark phase concentrated along both the footwall and hanging wall of the dike.

Ore zone #3 is located within a dark-phase, albitized

. 0 0 tonalite dike that strikes N70 E and dips 70 south. Ore

0 zone #2 is in a light-phase tonalite dike that strikes NGO

0 E and dips 80 south. Both dikes are located approximately

250m north of the main dike (Figure 4). It is possible that the tonalite dike of ore zone i2 may be an extension of the albitized tonalite of ore zone i3.

Thirty-five meters south of the main dike, a smaller dike approximately 3.0 to 4.0m wide makes up ore zone i5 (Figure 4). No work has been done on this zone since its original trenching. 39

Petrography

Fine-Grained, Dark-Phase, Albitized Tonalite

The dark phases of the albitized tonalites are hypid iomorphic to allotriomorphic granular and fine-grained

(Figure ll). Color ranges from dark gray on fresh surfaces to a light brown to gray on weathered surfaces. Occasion ally the dark phase has a slightly gneissic appearance. rntergrowths and megacrysts of albite and quartz produce a seriate porphyritic texture in some sections.

The dark phase consists of albite, quartz, carbonate, and an intergrowth of quartz and albite. Other minor constituents include: biotite, chlorite, ilmenite, magnetite, pyrite, rutile, zircon, and white mica (Figure

12). Modal analyses of the dark phase are given in Table

6. Microprobe analyses of various minerals are given in

Table 7.

Subhedral to anhedral albite grains are up to 2.5mm in length and analyzed grains ranged in composition from

Ano.a to An 3_6 . Both Carlsbad and albite twinning are common with grains commonly bent and some grains fractured and resealed with carbonate, sericite, and chlorite. The grains are fairly fresh with only minor alteration to sericite. Replacement of albite to various degrees by quartz is common. The quartz has replaced the albite along margins and twinning planes. Some remnant albite grains are seen surrounded by optically continuous quartz. Quartz also occurs as anhedral individual grains 40

TABLE 6

MODAL ANALYSES OF DARK-PHASE, ALBITIZED TONALITE DIKES

SAMPLE EA-9 EA-16 EA-19 Z3-4

----- Quartz 34.05 35.72 29.74 26.75

Plagioclase 49.12 46.90 53.69 54.48

Biotite 8.41 2.40 1.40 0.80

Chlorite 4.11 10.58 10.78 11.18 Ankerite - . - -. - 0.40 0.20 Calcite 1.37 2.40 2.59 3.59 Muscovite 0.39 - . - -. - -. - Apatite 0.20 -.- -. - -. - Epidote 0.20 0.20 -. - - . - Zircon pr. pr. pr. pr.

Magnetite 0.39 1.00 0.20 2.00

Ilmenite 0.39 0.80 1.20 1.00

Pyrite 1.37 -. - - • - -. - Hematite -. - -. - -. - -. - Rutile -. - - . - -. - -. -

Key: ?r.- presence confirmed in thin section but not detected ln modal analysis.

absent I -

Figure 11: Slab photograph of dark-phase, albitized tonalite (Sample EA-28).

Figure 12: Photomicrograph of dark-phase, albitized tonalite (Sample EA-19). Note the abundant fine-grained quartz and albite intergrowths with interstitial quartz and carbonate. Bar scale represents 1.0mm. I . 2 centimeters 43

TABLE 7.

MICROPROBE ANALYSES OF MINERALS IN DARK-PHASE, ALBITIZED TONALITES

SAMPLE EA-16 EA-16 EA-16 EA-16 Z3-4 Magnetite Biotite Chlorite Albite Biotite

Si02. 0.26 37.62 25.46 69.67 36.79 Al2.03 0.21 16.86 22.07 19.13 15.68 FeO* 94.54 20.32 29.16 0.15 19.67 MgO o.oo 10.79 12.30 o.oo 10.51 cao 0.11 o.oo 0.07 0;25 0.06 Na20 0.00 0.12 o.oo 11.17 o.oo K20 0.00 10.65 0.08 0.13 10.17 Ti02 0.00 1.83 0.00 o.oo 1.95 P205 o.oo o.oo 0.00 0.00 0.00 MnO o.oo 0.14 0.09 0.07 0.00 ClO 0.04 0.12 0.06 0.00 o.oo S03 0.00 o.oo o.oo o.oo o.oo Total 95.16 98.45 89.29 100.57 94.83

Number of Ions@ iI~: :· 1;.~:, . Si 0.01 2.80 2. 68 3.04 2.83 1.:.;;J ,( Al 0.01 1. 48 2.74 0.99 1.42 Fe2+ 0.98 1.26 2.57 1.27 Fe3+ 1.99 -.- Mg 1.20 1.93 -.- 1.21 Ca -.- 0.01 0.01 0.01 0.95 :;:·,., Na -.- 0.02 -.- L, •J:;, ' K 1.01 0.01 0.01 1.00 1) ·1a ~ ll ""' ~- Ti -.- 0.10 -.- 0.11 p -.- -.- Mn 0.01 0.01 -.- 0 4.00 10.00 10.00 8.06 10.00 OH 2.00 8.00 -.- 2.00

Key: * Total Fe as FeO @ See Appendix B, Section 2 for procedure used in normalization.

less than 0.005 or not used in normalization. 44

TABLE 7

(continued)

SAMPLE Z3-4 EA-19 EA-9 EA-9 EA-9 Albite Chlorite Albite Albite Ilmenite

Si02 68.58 25.12 68.50 67.53 0.31 Al203 18.74 21. 67 19.01 19.19 0.09 FeO* 0.78 29.12 0.16 0.08 46.98 MgO 0.00 12.64 o.oo o.oo 0.06 cao 0.30 0.11 0.28 0.75 0.05 Na20 11.26 0.14 11.38 11. 00 o.oo K20 0.11 0.12 0.15 0.18 0.09 Ti02 2.04 0.12 o.oo 0.05 50.42 P205 0.00 0.00 0.00 0.00 o.oo MnO 0.14 0.20 0.00 0.10 1.30 ClO 0.00 0.10 0.18 0.15 0.06 S03 o.oo 0.00 o.oo 0.00 0.09 Total 101.95 89.34 99.66 99.03 99.45

Number of Ions@

Si 3.02 2.66 3.02 3.00 0.01 Al 0.97 2.70 0.98 1.00 -.- Fe2+ 2.57 -.- -.- 0.93 Fe3+ 0.03 0.01 0.05 Mg -.- 1. 99 -.- Ca 0.01 0.01 0.01 0.04 Na 0.96 0.03 0.97 0.95 K 0.01 0.02 0.01 0.01 0.01 Ti -.- 0.01 -.- 0.97 p -.- -.- Mn -.- 0.02 -.- -.- 0.03 0 8.04 10.00 8.03 8.02 3.00 OH -.- B.00 -.- -.-

Key: * Total Fe as FeO @ See Appendix B, Section 2 for procedure used in normalization. less than 0.005 or not used in normalization. 45 which are generally less than 2.0mm in size and as inter locking mosaics of microcrystalline grains.

The complex relationships between quartz and albite for the dark phases are shown in Figures 13A-C. Types include: embayment of albite by optically continuous quartz, a granophyric intergrowth with or without an albite nucleus, or a microcrystalline mosaic of quartz and twinned and untwinned albite grains. Gradation from simple embay 1:"il: Hi~; ment to complex intergrowth is common. In some sections l(ll'j C II:. the intergrowths have a plumose or radial form. Quartz is ltZit ; Jr:!: ' always optically continuous in the intergrowth. Plagio 11C: 1u:.:,:u clase composition is similiar to the albite laths, J\C:,;·_

Ii!,,, generally less than An1.S· The ratio of stoichiometric albite to quartz and other trace constituents of the inter

:_'J;1 : growths ranges from 1:0.49 to 1:1.37 with a mean of 1:1.09. I,lli!f.'i '" . 1!l\,,i Interstitial subhedral to anhedral biotite occurs as grains 0.1mm to 1.0mm long and commonly displays chloritization and red-brown to brown-green pleochroism.

1< Zircon inclusions are present in some grains and produce dark ,,: \i n:ii.: brown pleochroic haloes. Biotite is abundant in some sections and minor in others which contain abundant chlorite. Minor amounts of chlorite are found interstitial to albite, quartz, and the intergrowths. It is also a common alteration product of biotite and fills fractures in albite along with carbonate. Seams of chlorite, biotite, and carbonate may also be present. Calcite and minor ankerite - 46

Figure 13: Variability of intergrowths in dark- and light-phase, albitized tonalites.

A. Embayment of albite by optically continuous quartz {qi in dark-phase, albitized tonalite (Sample z3-4). Bar scale represents 0.25mm.

B. Granophyric intergrowth with albite nucleus in dark-phase, albitized tonalite (Sample EA-19). Bar scale represents 0.15mm.

C. Interlocking mosaic of both twinned and un twinned albite and quartz in dark-phase, albitized tonalite (Sample EA-28). Bar scale represents 0.25mm •.

D. Embayment of albite by optically continuous quartz (ql in light-phase, albitized tonalite (Sample EA-17). Bar scale represents 0.25mm.

E. Granophyric intergrowth with albite nucleus in light-phase, albitized tonalite (Sample EA-14). Bar scale represents 0.25mm.

F. Interlocking mosaic of albite and quartz in light-phase, albitized tonalite (Sample EA- 20). Bar scale represents 0.25mm .

., .

are present in most sections.

Anhedral ilmenite grains up to 2.5mm in length are

present in most samples and are commonly found associated

with subhedral to anhedral magnetite. The ilmenite common

ly has a high manganese content (Table 7). Other opaques

include subhedral to anhedral rutile and pyrite.

Fine- to Medium-Grained, Light-Phase, Albitized Tonalite

The light phases of the albitized tonalites are very

similiar to the dark phases both texturally and mineralog

ically. The light-phase, albitized tonalites are hypidio

morphic to allotriomorphic granular, fine to medium

grained, and slightly more equigranular than the dark phase

(Figure 14). The visibly altered tonalite is different

texturally and will be discussed in the next chapter.

Color ranges from a light to medium gray on fresh surfaces

to a brownish gray on weathered surfaces. Occasionally the

light phase has a gneissic appearance. Mineral constit " uents include: albite, quartz, quartz/albite intergrowths

replacements-mosaics, carbonate, chlorite, biotite, white mica, apatite, pyrite, ilmenite, magnetite, rutile, and

zircon (Figure 15). Modal analyses for the light phase are given in Table 8, while microprobe analyses for represent ative minerals are given in Table 9.

Subhedral to anhedral albite laths range in size from

0.1mm to 3.0mm. Both albite and Carlsbad twinning are common. The analyzed grains ranged in composition from

An 0_3 to An 6_6 • The grains are commonly bent and fractured Figure 14: Slab photograph of light-phase, albitized tonalite (Sample EA-14).

Figure 15: Photomicrograph of light-phase, albitized

I, tonalite (Sample EA-33). Note the numerous '1 intergrowths of quartz and albite along with individual grains of albite and quartz with interstitial quartz and carbonate. Bar scale represents 0.25mm.

TABLE 8

MODAL ANALYSES OF LIGHT-PHASE, ALBITIZED TONALITE DIKES

SAMPLE EA-14 EA-17 EA-21 Z2-9

Quartz 33.59 28.70 12.54 21.36

Plagioclase 47.78 60.40 78.48 54.89

Biotite pr. 2.57 0.40 0.74

Chlorite 9.78 l. 78 0.60 3 .13 Ankerite -.- 3.76 -. - 16. 39 Calcite 6.09 1.00 - • - 0.74 Muscovite - . - -. - 0.80 0.18 Apatite 0.37 0.20 0.80 0.18

Epidote - . - -. - -• - -. - Zircon pr. -. - -. - - . - Magnetite 1.48 1.00 -. - 1.29 Ilmenite 0.92 0.59 0,80 0.92 Pyrite -. - pr. 5.58 0.18 Hematite -. - pr. pr. -. - Rutile -. - - . - pr. -. -

Key: pr.- presence confirmed in thin section but not detected in modal analysis.

absent 52

TABLE 9

MICROPROBE ·ANALYSES OF MINERALS IN LIGHT-PHASE, ALBITIZED TONALITES

SAMPLE ST-111 ST-111 EA-21 EA-14 UG-11 UG-11 Apatite Albite Rutile Magnetite Albite Albite

Si02 0.00 69.41 0.29 0.25 66.81 6 7 .15 Alz03 o.oo 19.21 0.11 0.21 20.57 '19.90 FeO* 0.00 0.07 1. 74 97.81 0.19 0.20 MgO o.oo 0.00 0.00 0.21 o.oo 0.00 cao 56.31 0.10 0.00 0.04 1. 38 1.34 Na2o 0.14 11.61 0.00 0.00 10.74 10.76 KzO 0.10 0.11 0.00 0.00 0.12 0.07 Ti02 0.06 0.00 97.16 0.05 0.07 0.16 Pzos 44.94 0.00 o.oo 0.00 0.00 0.00 MnO 0.00 0.13 0.00 0.00 o.oo 0.00 ClO o.oo 0.00 o.oo 0.08 0.00 0.00 S03 0.00 0.00 o.oo 0.00 o.oo 0.00 Total 101. 55 100.64 99.30 98.69 99.88 99.5B

Number of Ions @ Si -. - 3.12 -. - 0.01 2.94 2.97 Al -. - 0.94 -. - 0.01 1.07 1.04 Fe2+ -. - - . - -. - 1.00 -. - -. - Fe3+ -. - - . - -. - 1.97 0.01 0.01 Mg -• - - .- -. - 0.01 -. - -.- Ca 4.89 -. - -. - - . - 0.07 0.06 Na 0.02 0.93 -. - - . - 0.91 0.92 K 0.01 0.01 -. - - . - 0.01 0.01 Ti -. - -. - 1.00 - . - -. -- .- p J.oe -.- -. - - . - -. - -. - Mn -. - -.- -. - -. - -. --. - 0 12.11 8.12 2.00 4.00 8.03 8.04 OH 1.0 -. - -. - -. - -• - - . -

Key: * Total Fe as FeO

@ See Appendix B, Section 2 for procedure used in normalization.

less than 0.005 or not used in normalization. 53

TABLE 9

(continued)

SAMPLE EA-17 EA-17 Z2-6 Z2-6 Z2-9 Chlorite Albite Chlorite Albite Biotite

SiOz 25.84 69.27 33.15 68.59 38.14 Alz03 20.98 19.30 17.41 19.07 16.80 FeO* 26.24 0. 08 26.36 0.20 21. 93 MgO 15.40 o.oo 10.22 0.00 8.88 Cao 0.08 0.22 0.09 0.22 0.13 NazO 0.00 11.19 o.oo 11.06 o.oo KzO o.oo 0.13 0.00 o.oo 9.49 TiOz 0.04 0,04 0.14 o.oo 1.88 P205 o.oo o.oo o.oo o.oo o.oo MnO 0.13 0.09 0.09 o.oo 0.08 Clo o.oo o.oo 0.05 0.00 0.07 S03 0.00 o.oo 0.08 o.oo 0.00 Total 88.71 100.32 87,59 99.14 97.40

Number of Ions@

Si 2.70 3.03 3.44 3.04 2.86 Al 2.58 1.00 2.13 0.99 1.49 Fe2+ 2.29 -.- 2.29 -.- 1.38 Fe3+ -.- -.- 0.01 Mg 2.40 1.58 -.- 1.00 Ca 0.01 0.01 0.01 0.01 0.01 Na 0.95 -.- 0.95 -.- K 0.01 -.- -.- 0.91 Ti -.- -.- 0.01 -.- 0.11 p -.- -.- -.- -.- Mn 0.01 -.- 0.01 -.- 0 10.00 8.07 10.00 8.07 10.00 OH 8.00 -.- 8.00 -.- 2.00

Key: * Total Fe as FeO

@ See Appendix B, Section 2 for procedure used in normalization. less than 0.005 or not used in normalization. 54 with carbonate, sericite, and chlorite resealing the

fractures. As in the dark phase, the grains are relatively fresh with little alteration to sericite. Quartz in filtrates and replaces the albite grains along their margins. Quartz also occurs as anhedral grains generally

less than 1.5mm, interlocking fine-grained mosaics, and in quartz veinlets.

The complex relationships between quartz and albite in the light phase are very similiar to those in the dark phase. Embayment of albite by quartz, granophyric inter growths with or without an albite nucleus, and fine-grained mosaics of albite and quartz are common (Figures 13D-F).

The intergrowths are generally coarser-grained than in the dark phase. The ratio of stoichiometric albite to quartz ranges from 1:0.95 to 1:1.78 with a mean of 1:1.29. The plagioclase in the intergrowth is similiar chemically to the albite grains, generally more albite-rich than Anr.9 Carbonate cccurs interstitially, in veinlets, and reseals fractures in albite. carbonate is slightly more abundant in the light phase than in the dark. Both calcite and ankerite are present.

Chlorite occurs as interstitial blades and clusters and also as an alteration product of biotite. In one section, chlorite occurs interstitially in what appears to be a brecciated light-phase, albitized tonalite. Biotite occurs in minor amount~ in some sections with distinct brown plecchroism and occasional zircon inclusions with 55 dark brown pleochroic haloes. Both chlorite and biotite are much more abundant in the dark phase.

Minor euhedral to subhedral apatite is present in the light phase and is rare in the dark phase. The hexagonal and prismatic grains are generally

The occurrences of opaques in the light phase are very similiar to those in the dark phase. Metasomatic pyrite cubes make their appearance in the altered zones, while magnetite and ilmenite occur as subhedral to anhedral grains, aggregates, and dustings in various minerals.

Chemistry

Major and trace element chew.ical analyses and CIPW normative ·mineralogy for nine samples of the dark phase and twelve samples of the light-phase, albitized tonalites are given in Tables 10 and 11 respectively. The albitized tonalites range from acidic to intermediate with the range in Sio2 from 61.90% to 67.94% in the dark phase and 64.24% to 70.15% in the light. The dike from ore zone #2 appears to be a highly altered, light-phase tonalite, accounting for its high Cao (up to 7.49%), and CO 2 (up to 7.31%) contents and low Si02 content (down to 55.94%). Twelve of the twenty-one samples are acidic (Si02 >66%), while all of the samples are peraluminous (Alz03 > NazO+KaO+CaO). The albitized tonalites are easily distinguished from the other intrusive rock types based on their high total iron content and their low KzO content. 56

The dark phase generally has more biotite and chlorite

than the light phase (Tables 6 and 8). Because of this difference the dark phase generally plots closer to the F and M corners on the AFM diagram than dces the light phase

(Figure 16B). Chemically, the light phase has a higher

Na o ccntent and lower K o content than the dark phase. 2 2 This shows up nicely on Figure 17. The dark phase generally plots closer to the Or and K corners of the Q-Ab

Or and K-Na-Ca diagrams respectively. The presence of potassium in biotite may account for the higher normative orthoclase in the dark phase.

The albitized tonalite dikes show scatter on the QAP diagram (Figure 16A). The light phase plots in the tona

lite field-(7), the granodiorite field (3), granite field

(2), quartz monzodiorite field (2), and the quartz syenite field (1). The dark phase plots in the granodiorite field (4), granite field (3), and tonalite field (2). Potassium in biotite accounts for the high normative orthoclase content and the scatter towards the alkali feldspar corner.

The albitized tonalite dikes show no calc-alkaline

trends and show questionable trondhjemitic trends (Figure

17). Both phases are similiar in composition to the average tonalite listed by Nockolds (1954, p.1015)

except for higher total iron, Na o, and Ti02 contents and 2 lower Alzo3, Cao, and KzO contents in the dikes. 57

TABLE 10

CHEMICAL ANALYSIS AND CIPW NORMATIVE MINERALOGY OF DARK-PHASE, ALBITIZED TONALITE DIKES

SAMPLE E:A-28 EA-29 EA-9 EA-15 EA-16 EA-19

Si02 66.00 67.90 65.80 66.34 67.94 65.90 Al203 12.24 12.19 11. 73 12 .12 12.03 11.39 Fe203 3.84 2.36 2.72 2.96 2.69 2.29 FeO 5.18 3.18 3.67 4.00 3.64 3.09 MgO 2.07 1.77 • 1.73 1.50 1.93 1. 92 ' Cao 1.32 2.83 1.56 3.66 1.78 3,88 .,,,,:, Na20 3.77 4.71 4.72 2.96 5.13 4.92 1.10 .." K20 0.74 1.03 1.61 0.29 0.08 L{ Ti02 0.69 0.74 0.85 0.84 0.73 0.73 P205 0.20 0.17 0.23 0.26 0.14 0.14 ," MnO 0.05 0.05 0.03 0.06 0.05 0.09 Total 96.46 96.64 94.07 96.31 96.35 94.43

Cr 3.7 7.3 3.1 7.7 2.4 1.8 Co 57.6 34.7 39.0 39.4 40.7 31. 8 Ni 9.9 11.6 8.9 7.8 14.2 12.0 Cu .68. 7 7.7 18.5 190.4 7.7 8.4 Zn 33.8 28.8 124.7 136.9 35.6 21.1 Rb 29.6 16,7 26.9 30.9 10.0 5.1 ' Sr 65.8 68.0 72.1 45.5 74.1 80.1 • y 235.3 272.6 205.4. 205.2 306.7 316. 5

Zr 5 73. 5 642.1 603.2 560.7 666.4 679.6 ,(: Nb 27.2 29.3 27.7 26.0 30 .3 30,5 Ba 425.2 101.4 81.6 324.4 64.3 0.0 Pb 12.3 14.1 12.8 9.0 11.6 11.3 As 54.7 50.1 55.3 58.7 63.2 52.2 s 0.0 o.o 1123.1 206.5 0.0 0.0

QZ 33.28 29.84 29.44 33.52 30.28 28.61 OR 6.74 4.53 6.47 9.88 1. 78 0.50 AB 33.07 41. 24 42.46 26.01 45.05 44.09 AN 5.43 10.28 6.63 15.61 8. 22 9.27 WO 0.00 0.00 o.oo 0.00 0.00 o.oo DI 0.00 .2. 53 o.oo 1.23 o.oo 8.24 HY 10.84 6.19 7.92 7.03 8.45 3.96 co 3.03 0.00 0.60 o.oo 0.39 0.00 MT 5,77 3.53 4.19 4.46 4 .05 3.51 IL 1.36 1. 45 1.72 1.66 1.44 1.4 7 AP 0.48 0.41 0.57 0.63 0.34 0.34 58

TABLE 10

(continued)

SAMPLE EA-22 Z3-4 Z3-7

Si02 66.55 65.84 61. 90 Al203 12.48 12.18 12.23 Fe203 3.30 3.04 3.82 FeO 4.45 4.11 5.16 MgO 1.38 2.04 2.84 cao· 1.80 2.72 4.05 .. Na20 4.55 5.93 5.03 ...l!:'.!', K?O 0.53 0.21 0.09 •• 0.84 1. 00 1. 24 .. T102 !Ii! Pz05 0.25 0.26 0.34 ~~ MnO 0.03 0.06 0.11 Total 96.16 97. 39 96.81 ,"f',,

Cr 5.4 4.1 6.0 Co 53.7 45.2 52.2 Ni 9.2 7.7 2.8 Cu 24.7 7.7 7.9 ,; Zn 47.9 45.7 64.1 Rb 13.7 8.8 6.0 ":Ji,~-, Sr 85.0 112.5 129.0 li":•~:, y 224.4 140.0 115.4 Zr 547.0 443.1 391. 7 Nb 25.2 21.7 18.8 Ee 130.9 o.o 0.0 Pb 12.7 12.8 12.3 As 56.7 53.7 58.8 n'I' s o.o 26.9 97.9 .,'l " QZ 32.21 22.66 20.55 OR 3.26 1.27 0.55 AB 40.04 51.52 43.96 AN 7.59 6.16 10.87 WO 0.00 0.00 o.oo DI o.oo 4.87 6.18 HY 7.86. 6.42 8.91 co 1.82 0.00 0.00 MT 4.98 4.53 5.73 IL 1.66 1.95 2.43 AP 0.60 0.62 0.82 59

TABLE 11

CHEMICAL ANALYSIS AND CIPW NORMATIVE MINERALOGY OF LIGHT-PHASE, ALBITIZED TONALITE DIKES

SAMPLE UG-10 UG-12 UG-14 UG-17 UG-22 UG-24

Si02 65.91 65.95 66.96 65.67 68.08 70.15 Al203 12.52 11. 95 12.27 11.94 13.24 12.87 Fe203 3.40 2.87 2.63 2.78 2.69 2.75 FeO 4.59 3.88 3.55 3. 75 3.64 3.72 MgO 1.17 1.74 1.44 1. 82 1.70 1. 71 Cao 2.79 2.48 3.20 2.82 0.65 1.14 Na20 7.39 5.31 5.76 5.57 6.39 6.68 7 K20 0.21 0.03 0.03 0.03 0.11 0.09 Ti02 0.58 0.76 0.77 0.79 0.85 0.77 ' P205 0.22 0.25 0.26 0.25 0.27 0.25 :r. MnO 0.05 0.05 0.06 0.05 0.02 0.04 Total 98;83 95.24 96.93 95.47 97.64 100.17 '

Cr 11.3 6.6 4.6 7.0 o.o 4.1 Co 54.3 47.0 43.4 43.2 51. 7 56.1 • Ni 3.3 10.3 10.9 10.5 11. 6 11. 2 "' Cu 8.9 12.7 8.4 7.7 7.7 25.0 '•• Zn 23.8 46.7 53.5 41.9 57.1 73.6 £.', Rb 9.7 4.4 4.7 4.5 7.1 7.5 Sr 223.6 103.8 112.5 129.0 114.8 119.2 y •<" 91. 4 237. 9 221.1 216.8 243. 2 235.6 u Zr 503.6 516.1 512.l 491.8 5 72 .5 5 70. 3 Nb 23.5 27.4 25.5 25.6 30.l 29.5 ,c;"\" Ba o.o 0.0 0.0 o.o o.o o.o ..1-'c ••I Pb 24.1 14.5 14.5 10.9 13.4 14. 0 il As 45.3 52.6 52.9 55.1 49.4 52.2 ~ s 329.0 255.8 o.o o.o 42.2 55.9

QZ 15.64 27.86 25.85 25.78 26.55 25.10 OR 1.26 0.19 0.18 0.19 0.67 0.53 AB 63.27 47.16 50.28 49.37 55.38 56.43 AN 0.37 9.11 7.77 7.84 1.50 4.02 WO 0.00 0.00 0.00 0.00 0.00 o.oo DI 10.24 1.72 5.65 4.18 0.00 0.00 HY 2.60 7.47 4.20 6.24 7.49 7.60 co o.oo 0.00 0.00 0.00 2.12 0.31 MT 4.99 4.37 3.93 4.22 4.00 3.98 IL 1.11 1.52 1.51 1.57 1. 65 1. 46 AP 0.52 0.61 0.62 0.61 0.64 0.58

l ·~ , 60

TABLE 11

(continued)

SAMPLE UG-26 UG-29 EA-14 EA-17 EA-32 Z2-9

Si02 67.02 67.29 64.24 67.15 67.11 57.46 Alz03 12.09 11. 56 11.65 11.42 11.36 11.07 Fe203 2.54 1.97 2.58 1.88 2.21 2.68 FeO 3.44 2.66 3.47 2.54 2.99 3.61 MgO 1.40 1.43 1.70 1.22 1.56 2.11 • Cao 3.38 3.25 3.98 2.84 1.95 6.86 ,,.,,"' Na20 5.66 6.32 5.35 6.48 6.42 6.04 '"' K20 0.08 0.41 0.04 0.25 0.10 0.08 ..."" !~ Ti02 0.75 0.74 0.81 0.71 0.72 1.04 ;;.!' P205 0.19 0.16 0.23 0.16 0.21 0.24 ::~ : MnO 0.06 0.06 0.06 0.05 0.05 0.13 ;;:

Total 96.61 95.85 94.11 94.70 94.68 91. 32 ilci

Cr 3.7 10.0 0.7 3.5 5.7 10.2 Co 42.1 32.3 36.2 28.8 36.4 32.9 Ni 13.5 10.0 8.9 12. 3 13.5 4.6 Cu 8.3 16.4 7.7 9.0 12.0 9.6 Zn 34.9 53.1 36.6 39.3 56.1 41.6 {:( ~;\I Rb 6.1 16.3 4.0 14.2 5.7 5.2 fC', Sr 128.4 170.1 85.8 137.9 120.8 312.1 i~' y 295.9 236.4 225.0 204.3 286.9 107.6 ;,.-, 620.3 635.3 552.0 663.2 636.7 410.9 Zr :..1' Nb 29.2 29.2 26.7 29.2 30.7 17.0 123.6 0.0 o.o o.o •': Ba o.o o.o ;.1,, Pb 15.4 10.6 15.4 13,8 11.6 14.7 ,,.i'i, As 53. 6 60.7 50.0 51.1 55.1 52.4 .~. s 107.2 477.9 0.0 o.o 50.0 1076.4 ~,.!.,

QZ 26.25 25.13 24.93 23.92 25.03 10.85 OR 0.49 2.53 0.25 1.56 0.62 0.52 AB 49.57 55.79 48.10 57.90 57.38 55.97 AN 7,60 2.05 8.13 1. 41 1.99 3 .13 WO o.oo 0.00 0.00 0.00 o.oo 4.04 DI 6.98 11.14 9.21 10.10 5.53 18.48 HY 3.35 0.53 3.21 0.42 4 .10 0.00 co 0.00 0.00 0.00 0.00 0.00 0.00 MT 3.82 2.98 3.97 2.88 3.39 4.25 IL 1.47 1.47 1.63 1.42 1.44 2.16 AP 0.46 0.39 0.57 0.39 0.52 0.61 61

I[ 1: {(',' Figure 16: Triangular QAP and AFM plots of the dark- and ifI, light-phase, albitized tonalites. ,,,.-. ' A. Q=normative quartz, A=Or(Or+Ab+An)/(Or+An), ,, and P=An(Or+Ab+An)/(Or+An), where An=normative anorthite, Or=normative orthoclase, and Ab= normative albite (after LeMaitre, 1976a). Classification after Strecke~sen (1976).

B. A=Na20+K20, F=Fe0+0.8998(Fe203), M=MgO, ! all in weight percent. The diagram is divided into tholeiitic (Th) and calc-alkaline (C) fields after Irvine and Barager (1971).

•- Dark-Phase, Albitized Tonalite

o- Light-Phase, Albitized Tonalite

•- Dark-Phase, Albitized Tonalite-Modal Analysis-Data from Table 6.

c- Light-Phase, Albitized Tonalite-Modal Analysis-Data from Table 8. A. Q

GRANITE•

B. F

i·

·"' - Figure 17: Triangular Q-Ab-Or (normative quartz, albite, and orthoclase) and K-Na-Ca (potassium, sodium, calcium) plots of the dark- and light-phase, albitized tonalites. ,,' A. Generalized paths of calc-alkaline (C) and trondhjemitic (T) trends (Barker and Arth, 1976).

B. Trends for calc-alkaline (C) and trond hjemitic (T) suites (Barker and Arth, 1976).

•- Dark-Phase, Albitized Tonalite

o- Light-Phase, Albitized Tonalite

r; "H A. Q

~t,1' ,,J •"II". ..'" ' 0~

A Or )11

B. t:.i-

•-' I! 65

2.4 GRANITIC AND QUARTZ MONZONITIC ROCK TYPES

General

The rock types in this group include: the Crossecho

Stock granite, the quartz-feldspar and feldspar porphyry dikes, the quartz monzonite stock, and the quartz porphyry body and dikes.

The Crossecho Stock is a large, 5.6km by 3.2km, ellip tical stock of granite that is located along the southwest " shores of Crossecho Lake (Figure 5). The massive granite • forms prominent ridges. Webb (1948) noted the irregular periphery of the stock and observed dikes of granodiorite, porphyry, and pegrnatite.cutting the surrounding greenstone ., and showing field relationships to the stock. '

The feldspar and quartz-feldspar porphyries are found in small dikes and sills striking generally southwest to northeast throughout the study area. In the east extension a quartz-feldspar porphyry dike crosscuts both the basic volcanics as well as the main albitized tonalite dike.

Near ore zone i3 a quartz-feldspar porphyry dike crosscuts a band of spherulitic lavas, and in ore zone 12 a dike crosscuts the light-phase, albitized tonalite. Quartz feldspar porphyry dikes also crosscut the quartz porphyry intrusive body a long· its northern boundary (Armstrong,

1951). The relationship between the felpspar porphyries and the quartz-feldspar porphyries is unclear. In ore zone i2 a dike of quartz-feldspar porphyry grades into a feldspar 66 porphyry to the west. Frohberg (1952) suggested that feldspar porphyries distinctly older than the quartz porphyries exist and that they are different than the feldspar porphyries found grading from the quartz-feldspar porphyries.

Approximately 260 meters to the northwest of

Goldlund's shaft, a small, 700m by 150m, elliptical stock of quartz monzonite is located (Figure 4). The stock is defined by scattered outcrops with the central area obscured by low ground. The exact age of the stock is unknown. Armstrong (1951) called the stock a grey biotite granodiorite but suggested that the stock was younger than the granodiorite of the ore zones. The offshoots of the stock locally grade into a porphyritic phase and appear to be related to the quartz-feldspar porphyry dikes of the area. Small offshoots of the quartz monzonite near the

';" southern periphery of the stock crosscut the surrounding

Keewatin volcanics. ' '/1

A large, 850 by 1800m, intrusive body of quartz porphyry is located approximately 0.3km west of Franciscan

Lake (Figure 4). The body is defined by erratic outcrops, forms prominent ridges, and is sheared at N30QE to N55QE with dips 80° to 95Q north and south. Quartz porphyry dikes found underground in ore zone #1 and a small mass located 15m east of ore zone #2 are very similiar to the porphyry at Franscisca~ Lake. The age relationships between the intrusions at these three locations are 67 unknown. Armstrong (1951) suggested a pre-Algoman age for the body and younger ages for the underground dikes of ore zone #1 and the mass of ore zone #2. The quartz porphyry body crosscuts the enclosing basic lavas as seen by the apophysis along the western periphery of the body (Figure 4). Underground, in ore zone #1, the dikes cut the main albitized tonalite dike. The porphyries are crosscut in places by quartz veins ranging from 3.0mm to 160.0mm wide. • ' Petrography '• A petrographic summary of the granitic and quartz ' ' monzonitic rock types is given in Table 12. Slab photo graphs and photomicrographs of quartz porphyry, quartz monzonite, quartz-feldspar porphyry, and the Crossecho

Stock granite are given in Figures 18 through 25 respectively.

The major phenocryst minerals of the quartz porphy 'I ries are quartz and plagioclase. Accessory minerals in clude: sphene, apatite, ilmenite, and pyrite. Microprobe ' 'l analyses of various minerals are presented in Table 13.

The quartz phenocrysts are commonly embayed, rounded, and serrated with concentrations of sericite and carbonate bending around the phenocrysts (Figure 19). Rare plagio clase phenocrysts are found in the underground quartz porphyry dikes from ore zone #1 and from the mass adjacent to ore zone #2. Streaks and irregular patches of sericite are common throughout the groundmass and may be the remnants of ' '

1 • ! ;jl., f ! !. l1- ~.· i I J •- ,:.,7 a i i I • • •

; .I, ,, ',t 69

TABLE 13

MICROPROBE ANALSES OF MINERALS IN QUARTZ PORPHYRIES

SAMPLE MR-3 Z2-11 UG-7 UG-7 UG-4 Albite Ilmenite Albite Apatite Oligoclase (phenol (g .mass) (pheno) (g.mass) (phenol

Si02 68.77 0.25 68.80 o.oo 65.34 Al203 19.03 0.10 19.03 0.00 21.15 FeO* 0.06 45.62 0.11 o.oo 0.11 MgO 0.10 0.18 0.06 o.oo o.oo Cao 0.00 o.oo 0.13 57.66 4.82 Na20 10.80 o.oo 10.84 o.oo 7.76 K20 0.11 0.04 0.10 o.oo 0.04 Ti02 0.00 52.40 0.00 0.00 0.06 P205 o.oo 0.00 o.oo 44.29 0.00 MnO 0.00 1.54 o.oo 0.00 0.06 ClO o.oo 0.00 0.00 0.05 0.00 S03 0.00 0.10 o.oo o.oo o.oo Total 98.95 100.23 99.07 102.00 99.34

Number of Ions@

Si 3.06 3.05 2.95 Al 1.00 -.- 0.99 1.13 Fe2+ -.- 0,95 -.- -.- Fe3+ -.- 0.02 0.01 -.- 0.01 Mg -.- -.- -.- -.- -.- Ca 0.01 -.- 0.01 4.98 0.23 Na o. 93 -.- 0.93 0.69 K 0.01 0.01 -.- Ti 0.99 p -.- 3.02 Mn 0.04 -.- -.- 0 8.05 3.00 8.08 12.03 8.18 OH -.- 1.00 -.-

Key: * Total Fe as FeO @ See Appendix B, Section 2 for procedure used in normalization.

-.- less than 0.005 or not used in normalization.

abbreviations used: pheno- phenocryst g.mass- groundmass 70 altered feldspars. Carbonate-quartz veinlets cut the porphyries in some samples. Groundmass from the under ground dikes of ore zone #1 contains more fine-grained quartz and less feldspars than the two quartz porphyry masses.

The quartz monzonite consists of zoned and unzoned plagioclase, quartz, biotite, and microcline microperthite

(Figure 21). Minor and accessory minerals include: zir con, apatite, sphene, epidote, chlorite, sericite, pyrite, magnetite, ilmenite and carbonate. Microprobe analyses of minerals of the quartz monzonite stock can be found in

Table 14. In hand specimen the white to light brown plagioclase, brown to black biotite, and the glassy quartz are conspicuous. High concentrations of epidote and chlorite in some samples may be the result of incorporation of material from the intruded greenstone.

The quartz-feldspar porphyries are easily distinguish ed from the feldspar porphyries by the presence of glassy quartz phenocrysts visible in hand specimen. No distinct chill margins are seen in either type of porphyry.

The most abundant phenocryst minerals in the quartz feldspar porphyries are plagioclase and quartz with compound phenocrysts of numerous plagioclase grains also common (Figure 23). Microprobe analyses for common minerals of both feldspar and quartz-feldspar porphyries can be found in Table 15. In hand specimens of the Crossecho Stock granite, pink 71

Figure 18: Slab photograph of quartz porphyry Sample (MR-4). Sheared with quartz phenocrysts in a microcrystalline matrix of quartz, feldspar, carbonate, and serici te •. L I' !l' Figure 19: Photomicrograph of quartz porphyry (Sample MR-5). Rounded and embayed phenocrysts of quartz (q) in a fine-grained to micro crystalline matrix of quartz, feldspar, carbonate, and sericite. Bar scale represents 1.0mm. Figure 20: Slab photograph of quartz monzonite (Sample OA-7). Large light-colored grains are mainly zoned and unzoned plagioclase with the interstitial darker areas mainly chlorite, ,,I biotite, and epidote. Figure 21: Photomicrograph of quartz monzonite (Sample OA-2). Altered and zoned plagioclase (zpl surrounded by unzoned plagioclase (albite), quartz, epidote, chlorite, and biotite. Bar scale represents 1.0mm.

TABLE 14

MICROPROBE ANALYSES OF MINERALS IN QUARTZ MONZONITE STOCK

SAMPLE OA-2 OA-2 OA-2 OA-2 OA-2 Oligoclase Apatite Albite Microcline Sphene

Si02 65.87 0.00 67.82 63.86 29.83 Alz03 20.67 0.00 19.37 17.35 2.83 FeO* 0.11 0.00 0.03 0.00 0.84 MgO 0.00 0.00 0.00 o.oo o.oo ' Cao 2.16 56.29 0.56 o.oo 28.52 .,' NazO 10.00 0.00 11.04 0.36 0.00 • K20 0.12 0.00 0.14 17.25 0.10 • Ti02 0.00 0.00 o.oo 0.17 34.68 Pz05 0.00 44.90 o.oo o.oo 0.56 MnO o.oo 0.00 0.07 0.11 o.oo ClO 0.00 0.00 o.oo 0.14 o.oo S03 0.00 0.00 0.05 o.oo o.oo Total 98.93 101.19 99.18 99.24 97.36

Number of Ions @ Si 2.94 -. - 3.01 2.98 0.99 Al 1.09 -. - 1.01 0.95 0.11 Fe2+ -. - -. - -.- - . - 0.02 ,, Fe3+ 0.01 - .- 0.01 -.- -.- " Mg -. - -. - - . - - . - - . - " Ca 0.10 4.91 0.03 -. - 1.01 Na 0.86 -. - 0.95 0.03 -. - K 0.01 -.- 0.01 1. 03 0.01 i~ Ti - . - - . - -. - - . - 0.86 " p -. - 3.09 -. - - . - -. - Mn -. - -.- -. - - . - -. - 0 8.07 12.14 8.06 7.92 4.90 OH - . - 1.00 -. - -. - -. -

* Total Fe as FeO @ See Appendix B, Section 2 fo procedure used in normalization. less than 0.005 or not used in normalization. -~··------

TABLE 14

(continued)

SAMPLE OA-2 OA-6 OA-6 OA-6 OA-7 Epidote Biotite Magnetite Ilmenite Albite

Si02 38.84 39. 29 0.46 0.98 68.36 Al203 22.11 14.71 0.24 0.27 18.61 FeO* 13.74 15.14 94.37 45.72 o.oo MgO 0.00 14.86 o.oo o.oo o.oo CaO 24.62 0.00 0.09 0.04 0.09 L Na20 o.oo 0.00 o.oo 0.00 11.42 ' K20 0.18 10.08 0.04 0.09 0.08 ' Ti02 o.oo 2.34 o.oo 48.31 o.oo ' P205 o.oo 0.00 o.oo 0.00 0.00 •' MnO 0.22 o.oo 0.00 1.27 o.oo '• Clo o.oo o.oo 0.04 0.00 0.00 ' S03 0.00 0.07 o.oo o.oo 0.00 Total 99.71 96.49 95.24 96.68 98.56

Number of Ions @

Si 3.04 2.89 0.02 0.03 3.03 Al 2.02 1.28 0.01 0.01 0.97 Fe2+ - . - 0.93 1.02 0.95 -. - Fe3+ 0.88 -. - 1.95 0.04 -. - Mg -. - 1.63 -. - - .- - . - Ca 2.05 -• - - . - -. - 0.01 Na -. - - . - -. - - • - 0.98 K 0.02 0.95 -. - 0.01 0.01 Ti - . - 0.13 -. - 0.94 -. - p -. - -. - -. - -. - -. - Mn 0 .02 - . - -. - 0.03 -. - 0 11.95 10.00 4.00 3.00 8.02 OH - . - 2.00 -. - -. - -. -

* Total Fe as FeO

@ See Appendix B, Section 2 for procedure used in normalization. less than 0.005 or not used in normalization. 75

TABLE 15

MICROPROBE ANALYSES OF MINERALS IN FELDSPAR AND QUARTZ FELDSPAR PORPHYRIES

SAMPLE EA-11 EA-11 EA-11 EA-24 EA-11 Albite Apatite Biotite Albite Sphene (g.mass) (g.m.;,ss) (g.mass) (pheno) (incl) -·--···------Si02 68.87 0.00 36.94 69.46 31. 51 Al203 20.01 o.oo 15. 73 19.97 2.97 FeO* 0.06 0.00 16.12 0.16 0.78 MgO 0.21 0.05 13.88 0.14 0 .14 CaO 0.45 56.44 0.09 0.37 30.36 Na20 10.77 0.13 0.80 10.69 0.10 K20 0.18 o.oo 10.39 0.18 o.oo Ti02 0.11 o.oo 1. 96 0.00 36.72 Pz05 0.00 44.25 o.oo o.oo 0.00 MnO o.oo 0.00 0.07 o.oo 0.27 ClO 0.06 0.00 0.11 0.00 o.oo S03 o.oo o.oo o.oo 0.05 o.oo Total 100.72 100.87 96.02 101.02 102.85

Number of Ions@ Si 3.02 -.- 2.78 3.03 0.97 Al 1.13 -.- 1.39 1.03 0.11 Fe2+ -.- 1.01 0.02 Fe 3+ -.- 0.01 Mg -.- 1.55 -.- 0.01 Ca 0.02 4.93 0.01 0.02 1.01 Na 0.91 0.02 0.12 0.91 0.01 K 0.01 1.00 0.01 -.- Ti 0.11 0.86 p -.- 3.05 -.- Mn -.- 0.01 0 8.07 12.07 10.00 8.10 4.88 OH -.- 1. 00 2.00 -.-

Key: * Total Fe as FeO @ See Appendix B, Section 2 for procedure used in normalization.

-.- less than 0.005 or not used in normalization.

abbreviations used: pheno- phenocryst g.mass- groundmass incl- inclusion 76

TABLE 15

(continued)

SAMPLE Z2-l Z2-13 Z2-13 i Z2-17 i Z2-17 Albite Ilmenite Apatite Albite Albite (phenol lg.mass) (g.mass) (pheno) (g.mass)

Si02 69.95 0.34 0.00 68.81 68.70 Al203 19.24 0.12 0.00 19.42 19.31 FeO* 0.00 46.83 0.16 0.00 0.00 MgO 0.11 0.27 0.00 0.00 0.06 Cao 0.16 0.11 56. 73 0.24 0.30 Na20 10.84 0.00 0.09 10.72 10.58 KzO 0.12 0.00 0.00 0.11 0.14 Ti02 0.00 53.91 o.oo 0.00 o.oo Pz05 0.00 0.00 44.16 o.oo 0.00 MnO 0 .12 1.55 0.00 0 .10 0.06 ClO o.oo 0.00 0.00 0.08 o.oo S03 0.00 0.00 0.00 0.00 o.oo Total 100.54 103.13 101.14 99.48 99.15

Number of Ions@

Si 3.07 0.01 3.05 3.06 Al 0.99 1.01 1.01 Fe2+ -.- 0.93 Fe3+ 0.02 -.- Mg 0.01 Ca 0.01 -.- 4.95 0.01 0.02 Na 0.92 0.01 0.92 0.91 K 0.01 0.01 0.01 Ti 0.99 -.- -.- p -.- 3.04 -.- -.- Mn -.- 0.03 -.- -.- 0 8.10 3.00 12.06 8.09 8.12 OH -.- 1. 00 -.-

Key: * Total Fe as FeO i Feldspar Porphyry sample

@ See Appendix B, Section 2 for procedure used in normalization.

-.- less than 0.005 or not used in normalization. abbreviations used, pheno- phenocryst g.mass- groundmass 77 feldspar, glassy quartz, epidote, and green biotite flakes are conspicuous. The granite predominantly consists of zoned and unzoned plagioclase, quartz, microcline, biotite, and epidote, with minor sphene, zircon, chlorite, sericite, apatite, pyrite, and magnetite (Figure 25). Microprobe analyses for common minerals of the Crossecho Stock can be found in Table 16.

Chemistry

Major and trace element chemical analyses and CIPW normative mineralogy for two samples of quartz porphyry dikes, two samples of the quartz monzonite stock, six samples of quartz-feldspar porphyry, and five samples of the Crossecho Stock are given in Appendix Band Tables 17,

18, and 19 respectively.

The two quartz porphyry samples vary considerably in composition, with the Si02 content 64.77% and 73.33% and

Al203 content 17.23% and 13.47% respectively.

Of the two samples of quartz monzonite, one sample is acidic and the other is intermediate; both are pera luminous. The samples are similiar to the quartz-feldspar porphyries (Table 18) which could be offshoots of the stock. The quartz monzonite stock has higher Al203 and K20 contents and lower total iron and TiOz contents than the albitized tonalite dikes. The samples are similiar in composition to a sodium-rich granodiorite or tonalite or a Si02-rich monzonite. The quartz monzonite stock has rela tively high barium concentrations (1079.0-1280.lppm), and 78

,r:~,rl I!·. .. Figure 22: Slab photograph of quartz-feldspar porphyry j~";•lj_' •. '"" (Sample EA-24). Phenocrysts of albite and It .. ,~ f: glassy quartz in a quartz, feldspar, carbonate, IL' biotite, and sericite matrix.

Figure 23: Photomicrograph of quartz-feldspar porphyry (Sample EA-10). Albite phenocrysts with minor quartz phenocrysts in a fine-grained to micro-· crystalline matrix of quartz, feldspar, carbonate, biotite, and sericite. Bar scale represents 1.0mm.

Figure 24: Slab photograph of Crossecho Stock granite (Sample CLS-6). Note the light-colored feldspar and glassy quartz with darker colored epidote and biotite.

Figure 25: Photomicrograph of Crossecho Stock granite (Sample CLS-6). Interlocking mass of altered albite (a), microcline (ml, and biotite (b), also with quartz, epidote, chlorite, and sericite. Bar scale represents 1.0mm.

TABLE 16

MICROPROBE ANALYSES OF MINERALS IN CROSSECHO,STOCK

SAMPLE CLS-8 CLS-8 CLS-1 CLS-10 CLS-10 Oligoclase Biotite Albite Microcline Oligoclase

Si02 65.36 40.16 67.93 64.67 67.59 Al203 21.92 15.36 20.43 18.39 20.83 FeO* 0.21 12.39 0.00 o.oo 0.12 ~ MgO o.oo 16.47 0.00 0.00 0.00 r.-:.: cao 2.87 0.46 1.71 0.00 2.20 Li, Na20 9.40 0.21 10.37 0.37 9.96 ~~. 17.41 0.17 f " K20 0.12 10.85 0.31 :i. Ti02 0.00 1.52 0.00 0.63 0.00 •,_ Pz05 0.00 0.08 0.13 0.00 o.oo (L MnO 0.07 0.25 0.00 0.14 0.00 ClO 0.00 0.00 0.12 0.00 0.09 i'J,1 S03 0·.00 0.00 o.oo o.oo 0.00 Total 99.95 97.75 101.00 101.61 100.96

Number of Ions @

Si 2.90 2.90 2.97 2.96 2.96 Al 1.14 1.31 1.05 0.99 1.07 Fe2+ -. - 0.75 -. - -. - -. - Fe3+ 0.01 -. - -. - -. - - . - Mg -. - 1. 77 -. - - . - - . - Ca 0.14 0.04 0.08 -. - 0.10 Na 0.81 0.03 0.88 0.03 0.84 K 0.01 1.00 0.02 1.02 0.01 Ti -. - 0.08 -. - -. -- . - p -.- -. - -. - -. - -. - Mn -. - 0.02 -. - - . - - . - 0 8.08 10.00 8.05 7.93 8.05 OH -. - 2.00 - .- -. - -. -

Key: * Total Fe as FeO @ See Appendix B, Section 2 for procedure used in normalization. - - l~s than 0.005 or not usec in normalization. 81

TABLE 16

(continued)

SAMPLE CLS-4 CLS-4 CLS-6 CLS-6 CLS-6 Epidote Albite Apatite Sphene Epidote

Si02 38.67 68.82 o.oo 29.86 39.12 Al203 22.52 20.24 0.00 1.46 23.04 FeO* 13. 07 0.07 0.07 0.90 12.99 MgO o.oo o.oo o.oo o.oo 0.00 Cao 24.55 1. 51 56.62 29.30 24.99 Na20 0.57 10.18 0.00 0.19 o.oo K20 0.21 0.16 0.04 0.03 0.03 Ti02 0.06 0.05 o.oo 36. 97 0.00 P205 0.00 0.00 43.97 0.12 o.oo MnO 0.24 0.10 0.00 0.00 0.16 ClO 0.44 0.05 0.05 o.oo o.oo S0,3 0.23 0.00 0.00 0.00 0.00 Total 100.56 101.18 100.75 98.83 100.33

Number of Ions@ Si 2.98 3.01 -.- 0.97 3.01 Al 2.04 1.04 -.- 0.06 2.09 Fe2+ 0.03 Fe.3+ 0.84 -.- 0.83 Mg -.- -.- -.- -.- -.- Ca 2.02 0.07 4.96 1.02 2.06 Na 0.08 0.86 0.01 -.- K 0.02 0.01 -.- -.- Ti 0.91 -.- p 3.03 -.- -.- Mn 0.02 -.- -.- -.- 0.01 0 11. 87 8.09 12.04 4.91 11.97 OH 1.00 -.- 1.00 -.- 1.00

Key: * Total Fe as FeO

@ See Appendix B, Section 2 for procedure used in normalization.

less than 0.005 or not used in normalization. 82

TABLE 17

CHEMICAL ANALYSES AND CIPW NORMATIVE MINERALOGY OF QUARTZ MONZONITE STOCK

SAMPLE OA-2 OA-3

Si02 66.47 64.17 A1203 15.77 15.41 Fe203 0.77 0.82 FeO 1.04 1.11 MgO 1.86 1.63 cao 2.79 3.23 Na20 5.67 6.66 K20 2.59 1. 25 Ti02 0.23 0.27 P205 0.16 0.18 MnO 0.02 0.02 Total 97. 3 7 94.75

Cr 36.9 46.6 Cc 8.8 9.7 Ni 17.0 18.0 Cu 13.7 22.3 Zn 60.4 69.1 Rb 65.2 42.9 Sr 814.7 963.4 y 13.2 12.3 Zr 191.1 213.5 Nb 1.1 0.0 Ba 1079.0 1280.1 Pb 30.2 36.4 As 39.8 35.3 s o.o 10.6

QZ 15,89 13.46 OR 15.72 7.80 AB 49.28 59.48 AN 10.20 8.93 WO 0.00 o.oo DI 2.34 5.36 HY 4.60 2.74 co o.oo o.oo MT 1.14 1.25 IL 0.45 0.54 AP 0.38 0.44 83

TABLE 18

CHEMICAL ANALYSES AND CIPW NORMATIVE MINERALOGY OF QUARTZ-FELDSPAR PORPHYRIES

SAMPLE UG-20 EA-4 EA-11 Z2-13 OA-8 MC-3

Si02 65.11 65.19 62.62 66.03 63.62 61.98 Al2 0:3 15.80 15.47 14.75 16.39 16.18 15.64 Fe2011 0.84 0.79 0.87 0.92 0.88 0.72 FeO 1.14 1.06 1.17 1.24 1.19 0.96 MgO 1.42 1.34 1. 84 1.09 1.46 1.34 CaO 3.43 3.16 3.42 2.74 3.41 4.41 Na20 5.98 7.08 7.09 6.06 6.54 6.68 K20 1.61 1.33 1.28 1.64 1.64 1.58 Ti02 0.29 0.29 0.29 0.29 0.30 0.27 P205 0.12 0.09 0.11 0.12 0.15 0.16 MnO 0.02 0.02 0.02 0,03 0.02 0.03 Total 95.76 95.82 93.46 96. 55 95.39 93.77

Cr 28.4 25.4 38.0 34.9 41.8 15.1 Co 7.1 8.0 9.8 8.4 8.5 5.9 Ni 12.4 11. 9 19.6 11.8 19.2 8.7 '!, Cu 13.6 15.2 29.0 12. 6 17.9 18.5 Zn 40.4 64.9 65.7 44.9 68.9 67.4 Rb 41.9 45.7 36.6 36.4 45.9 51.3 Sr 709.7 709.1 788.3 345.4 753.4 723.5 y 12.4 13.7 12.8 12.1 12.7 13.5 Zr 190.8 192.5 196.6 166.1 195.6 172.4 Nb 2.9 2.8 1. 6 7.6 1.6 1.7 Ba 825.3 625.8 915.9 390.0 1059.4 898.7 Pb 21.5 21. 4 18.9 17.6 20.9 22.1 As 50.4 44.1 45.3 53.6 45.3 51. 6 s 4.6 20.0 1.3 139.7 0.8 125.8

QZ 16. 31 12.38 9.39 17.48 11. 62 9.05 OR 9.93 8.20 8.09 10.04 10.16 9.96 AB 52.84 62.52 64.19 53.11 58.01 60, 28 AN 12.02 6.79 4.97 13.13 10.43 8.56 WO 0.00 o.oo 0.00 o.oo o.oo 0.84 DI 3.93 7.14 9.87 0.11 5.01 9.27 HY 2.82 0.98 1. 28 3.89 2.47 o.oo co 0.00 0.00 0.00 0.00 0.00 0.00 MT 1. 28 1.19 1. 35 1.38 1.34 1.11 IL 0.58 0.57 0.59 0.57 0.60 0.55 AP 0.29 0.22 0.27 0.29 0.37 0.40 84

TABLE 19

CHEMICAL ANALYSES AND CIPW NORMATIVE MINERALOGY OF THE CROSSECHO STOCK

SAMPLE CLS-1 CLS-4 CLS-6 CLS-8 CLS-10

Si02 70.99 71. 71 69.52 68.01 68.86 Al203 14.56 14.67 16.64 17 .05 16.24 Fe203 0.24 0.25 0.50 0.54 0.39 FeO 0.32 0.34 0.67 0.74 0.53 " MgO 0.13 0.19 0.80 0.98 0.59 cao 0.91 0.98 2.43 2.70 1.77 'J: Na20 5.18 5.58 6.31 6.37 6.44 K20 3.99 3.46 1.83 1.61 1.71 Ti02 0.04 0.05 0.18 0.19 0.12 P2os o.oo 0.00 0.10 0.11 0.05 MnO 0.01 o.oo 0.01 0.01 o.oo Total 96.37 97.23 98.99 98.31 96.70

Cr 2.5 5.0 4.8 6.0 0.0 Co 0.0 0.0 3. 6 3.8 1.2 Ni 5.4 6.4 5.1 2.8 1.7 Cu . 10. 3 12.4 14.3 15.5 21.1 Zn 40.0 33.3 68.7 72.9 54.5 Rb 176.5 134.5 57.5 42.0 55.5 Sr 152.9 371. 7 719 .4 777.3 722.4 y 11.7 12.2 10.7 9.5 9.5 Zr 101.9 94. 9 157.1 170.5 148.0 Nb 11.6 8.3 2.8 1.0 2.3 Ba 406.1 291. 4 626.3 692.1 547.3 Pb 34. 0 29.4 24.8 18.7 21.8 As 31. 5 42.0 44.7 50.3 42.3 s 0.0 0.0 o.o o.o 0.0

QZ 24.16 24.17 19.64 17.89 20.81 OR 24.47 21.03 10.92 9.68 10.45 AB 45.48 48.56 53.94 54.83 56.35 AN 4.68 4.90 11.52 12.89 8.74 WO 0.00 o.oo o.oo 0.00 o.oo DI 0.00 0.08 0.00 o.oo o.oo HY 0.70 0.79 2.57 3.10 1.98 co 0.07 0.00 0.10 0 .19 0.72 MT 0.36 0.38 0.73 0.80 0.59 IL 0.08 0.10 0.35 0.37 0.24 ;·::; AP 0.00 0.00 0.23 0.26 0.12 ;./; 85 low arsenic concentrations (35.3-39.Bppm), compared to the other intrusive rock types.

Samples from various quartz-feldspar porphyries in the area are fairly similiar (Table 18). All except one sample are intermediate with the Si02 range from 61.98% to 66.03%, and all samples are peraluminous. The quartz-feldspar porphyry dikes are somewhat similiar in composition to the average for monzonite (LeMaitre, 1976b, no.17). The only ., differences are slightly higher Si02, higher Na20, and lower K20 contents in the porphyries.

All of the Crossecho Stock samples are acidic with the

Si02 content ranging from 68.01 to 71.71 weight percent.

All samples of the stock are peraluminous. The samples have the highest average Si02 content of all of the rocks examined. The stock is similiar chemically to the quartz feldspar porphyries and quartz monzonite stock, with the differences being higher average Si02 and K20 contents and lower Cao, MgO, total iron, and Na20 contents in the granite. The Crossecho Stock has lower concentrations of

C~, Co, Ni, ands than does either the quartz-feldspar porphyries or the quartz monzonite stock. Compared to an average granite (LeMaitre, 1976b, no.8), the stock general ly has higher Al2 o 3 and Na20 contents with lower total iron and K20 contents. On a QAP plot, both of the quartz porphyry samples and

4 of the 5 crossecho Stock samples plot in the granite field. The other Crossecho Stock sample, both quartz mon- 86

zonite samples, and all of the quartz-feldspar porphyry samples plot in the quartz monzonite field (Figure 26A). All of the samples plot in the calc-alkaline field on an AFM plot (Figure 26B). All of the samples combin,ed, with the possible excep tion of the quartz porphyry samples, show a calc-alkaline trend on a Q-Ab-Or plot (Figure 27A). On a K-Na-Ca plot the trend is not so well-defined (Figure 27B). The samples are displaced towards the sodium corner of the plot, and the quartz porphyry samples again plot away from the ether rock types as they did on the Q-Ab-Or plot. 87

Figure 26: Triang~lar QAP and AFM plots of the quartz monzonite stock, quartz porphyry dikes quartz-feldspar porphyries and crosse~h I Stock. ' o rl " "· A.d Q=normative quartz, A=Or(Or+Ab+An)/(Or+An) an P=An(Or+Ab+An)/(Or+An), where An=normative' anorth7te, Or=normative orthoclase, and Ab= norma~i~e a~bite (after LeMaitre, 1976a). Classification after Streckeisen (1976).

( " B. A=Na20+K20, F=Fe0+0.8998(Fe2o) M=M o 1c-·.' ~11 in weig~t.percent. The diagr~m' is divided i~to tholeiitic (Th) and calc-alkaline (C) fields after Irvine and Barager (1971). J-. o- Quartz-Feldspar Porphyries )1:,,. ,:· . Ir',-, i •- Quartz Monzonite Stock Ji- ., ·, :r -~ .-: o- Quartz Porphyry Dikes •- Crossecho Stock A. a

D GRANITE D

I'!

B. F

D 0 89 l i

JG:"'~ ··1r· j\,::.t,,;, tf."r:-; pc, Figure 27: Triangular Q-Ab-Or ~normative quartz, albite, l!!:d! ~.-- and orthoclase) and K-Na-Ca (potassium, sodium, ic:·/," calcium) plots of the quartz monzonite stock, ! ' ~ quartz porphyry dikes, and quartz-feldspar 1l' porphyries, and Crossecho Stock. l A. Generalized paths of calc-alkaline (C) and trondhjernitic (T) trends (Barker and Arth, 1976). j' f• ' B. Trends for calc-alkaline (C) and trond hjernitic (T) suites (Barker and Arth, 1976). o- Quartz-Feldspar Porphyries 1: f.'' •- Quartz Monzonite Stock hr: - o- Quartz Porphyry Dikes j( -, 1,: ., 11 '"' ' ;:: .: ' •- Crossecho Stock Jf ·;:.~-- A. a

',, '

a CHAPTER 3

MINERALOGY AND GEOCHEMISTRY OF ORE ZONE #1 AND THE OPEN PIT

3.1 VEIN MINERALOGY

The veins of the Goldlund deposit are fracture fillings striking transverse to the general trend of the albitized tonalite dikes from due north to N20°E with dips

0 0 from 30 to 70 to the west (Frohberg, 1952). The veins range in width from 30.0cm.

The veins are composed primarily of interlocking quartz grains up to 3cm in diameter and minor carbonate grains up to 2cm in diameter. Aggregates of major ankerite and somewhat lesser calcite are concentrated along the vein walls. Sheet-like ilmenite grains are occasionally found concentrated along the vein walls as well. Black tourmaline needles, scheelite, and actinolite have also been reported in the veins (Frohberg, 1952; Chisholm,

1951). Pyrite occurs in the veins as large cubes up to 16.0cm across, individual subhedral grains, and fine-grained aggregates. Other metallic minerals reported occurring in the veins include galena, sphalerite, altaite, petzite, gold, and pyrrhotite (Frohberg, 1952).

3.2 CHEMICAL AND MINERALOGICAL CHANGES ASSOCIATED ~HTH ALTERATION The veins at the Goldlund Mine occur mainly in the light-phase, albitized tonalite and are surrounded by

91 92 distinct alteration haloes (Figure 28). The haloes occur as bleached, light gray to pink-gray zones of albitized tonalite ranging from a few millimeters up to 1 meter in width. The width of the quartz veins has no apparent relationship to the width of the associated alteration halo or on gold grade. Some very thin veins have alteration haloes up to a meter wide, while veins several tens of centimeters wide may have haloes only millimeters in width.

Although most alter.ation occurs as a simple bleaching surrounding the veins, occasionally an inner, pyrite-rich, dark zone occurs next to the vein (Figure 29).

The visibly altered, light-phase, albitized tonalite consists of an interlocking mass of albite, quartz, carbon ate, and assorted accessory minerals (Figure 30). Albite occurs as euhedral to subhedral grains with little to no alteration. Albite, Carlsbad, and pericline twinning are present. The grains are commonly bent, fractured, and resealed with carbonate and quartz. Quartz occasionally embays and replaces the albite grains along the margins but not nearly as extensively as in the unaltered samples.

Granophyric intergrowths are almost totally absent in the visibly altered tonalite samples. Quartz occurs as an hedral grains and is .generally found interstitial to the albite. Large quartz grains commonly contain numerous fluid inclusions. Carbonate occurs interstitially as well as in eu hedral, rhombic-shaped grains. Euhedral ankerite commonly Figure 28: Slab photograph of quartz vein and associated alteration halo. Sample from the open pit.

zca- zone of cryptic alteration zva- zone of visible alteration

qv- quartz vein

1•-·

Figure 29: Slab photograph of zoned alteration around a r\·,:' quartz vein. Sample from stope l-27E. I' .. r:.:, .. zva- zone of visible alteration

J .. pz- pyrite-rich zone ';,r- qv- quartz vein it )F.·, u~.Jf ,t':;.

Figure 30: Photomicrograph of visibly altered, light-phase, albitized tonalite (Sample EA-13). Bar scale represents 0.25mm.

95 contains inclusions of quartz and albite.

Pyrite occurs as large, up to 16.0cm, euhedral to sub hedral cubes and as anhedral interstitial aggregates and individual grains. Occasionally biotite is found along the crystal faces of some of the euhedral cubes. Ilmenite is found in both aggregates and concentrated along the walls of the veins in sheet-like grains. Chlorite is very rare in the altered, albitized tonalite.

Chemical Changes

Two methods were used in a qualitative study of the chemical changes associated with hydrothermal alteration.

The first was to look at simple profiles of chemical data from the visible alteration haloes outward. The second method was to use the composition-volume equation of

Gresens (1967).

Alteration Profiles

Four alteration profiles were examined and results are presented in Figures 31 through 36. The purpose was to survey chemical changes that occur from the vein outward to the visibly unaltered wall rock. Simple comparison of visibly unaltered, light-phase tonalite samples and the visibly unaltered samples near the veins shows distinct compositional differences in all four profiles. This indicates that even the visibly unaltered samples near the veins have been affectea by the vein-forming fluids and represent an outer zone of cryptic alteration. 96

General patterns in chemical compositions are found within the visibly altered and cryptically altered wall rock of the Goldlund Mine. As the veins are approached the patterns include:

1) increase in Na2o weight percentage in all profiles,

2) general increase in Al203 weight percentage, and 3) general decrease in KzO, H20, and Fe203 weight

percentages.

Trace elements also show distinct patterns. Results are shown in Figures 35 and 36. As the veins are approached the patterns include:

1) increase in sulfur concentrationi

2) general increase in lead, copper, and strontium con-

centration;

3) general decrease in cobalt and arsenic concentration;

4) increase in zinc concentration in 3 of 4 profiles;

5) rapid decrease both towards and away from the vein in

barium and rubidium concentration from a high just

outside the zone of visible alteration;

6) inconsistent patterns in yttrium, niobium, zirconium,

nickel, and chromium concentrations.

Composition-Volume Calculations and Diagrams

The study of chemical variation.between unaltered and metasomatically altered rock equivalents requires consider ation of volume changes which may accompany the alteration

(Gresens, 1967; Babcock, 1973). Gresens (1967) proposed an equation that uses chemical analyses and specific gravities 97

11-. ·11· .j. Figure 31: Alteration profile from stope l-13E showing chemical changes produced by alteration of 1:. light-phase tonalite near the vein. Vertical dashed line divides the zones of visible and cryptic alteration. Vein- 2.5cm in width. ALTERATION PROFILE STOPE 113

62 8102

60 15 13 ~ I- • • z 11 Al•0 I.I.I 2 3 0 a:: 9 I.I.I a.. I- 7 ::i:: c., 20 Fe 2o I.I.I 5 8 ~ aO

3 02

gO 1

Q8 102 Q6

0.4 20 K20 Q2 p20,. Mn

·j,', 0

.·,::.-S 2 4 6 a 10

•' DISTANCE FROM VEIN (CM) 99

11, '",, Figure 32: Alteration profile from the open pit showing I,•.f che~ical changes produced by alteration of light-phase tonalite near the vein. Vertical 11·:_.:· dashed line divides the zones of visible and ff'· cryptic alteration. Vein- 4.0cm in width. JI.;.

- ALTERATION PROFILE OPEN PIT OP 6,6-r-----,------,

6 ... 13 ,.~-,

Al 0 ; 1'

11 I I- I z .I I w I 0 9 I a: I I w I 0.. I I- 7 I :c I I Na 0 0 I w I • I • • Fe o • :i: -r· . 2 3 .. • ~ I ---- I • I • Ceo 3 ...- I • • I ------. • I I MQ0 __. • I • • • • • • 1 1 I I I 0.8 I ..1-- • ~ 0.6 • • o I I I K20, I M I I I P205 Q2 I MnO 0 4 12 16 20

DISTANCE FROM VEIN (CM) II~

Figure 33: Alteration profile from the open pit showing chemical changes produced by alteration of light-phase tonalite near the vein. Vertical dashed line divides the zones of visible and cryptic alteration. Vein- 4.5cm in width.

Dotted line connects corresponding lines on both sides of vein. ALTERATION PROFILE OPEN PIT OP-3 a•i:;....----~------.------....

12 A1 o ~····· ...... 2 3 I . I-z w 0 I a: I w I a. I eNe o I- ...... 2 ;I: • I • • C, •2°s w ao ...... I 3: _...... I •CO2 I • • I I I I I I 2 I I • • I • gO 1 • •········ I I Q ltTI02 • • I • •--...... -..... • I • • I I 08 I I I 0.4 Q2

0 4

DISTANCE FROM VEIN. (CM) 103

,j,. Figure 34: Alteration profile from stope l-05CW showing chemical changes produced by alteration of light-phase tonalite near the vein. Vertical dahed line divides the zones of visible and cryptic alteration. Veins- 0.25cm and 2.7cm in width. ALTERATION PROFILE ST OPE 105CW 51,.,----,------,------,------...

6~___ ..______..,______...______..J 13...... -----r-----...... ------,------.

I 11 I I- I z l w I 0 I a: 9 I w l ll. I I I- I ::i: 0 w ~

0.8 ••--+-·---··-!---·...--·

0.4

0,,2

DISTANCE FROM VEIN (CM) 1,~ ' Jf-J_ •'L' C ' .;, . Figure 35: Alteration profiles of sulfur and arsenic ccncentration changes for samples from the fL,·•. open pit and stope 1-0SCW. Vertical dashed lines divide the zones of visible and cryptic alteration.

I' Dotted line connects corresponding lines on ;le,.,. both sides of vein. l,,,,. 1l"" a !l,f' :.1 1,:·cv :1•; ' ,'~ '111 ', ,,. :itt,;',.;. ALTERATION PROFILE OPEN PIT OP-3, As, s ··, ...... ::E IL IL -::E IL Q II. z < -z 0 :,"' 0 I- :x: < a: I- I- z I -z w f 0 f.) i s I I- z < g44 ! a: l I-z <.. w / f.) z ! 0 i' 0 i (0 f

4 0 4 DISTANCE FROM VEIN (CM)

ALTERATION PROFILE STOPE 105CW, As, S sa...--~~--.-~~~~~..--~~~~~~__.,..~.:..____;~~~ .... ::E IL IL Q z < :,"' 0 ,-:z: -z 0 <.. a: ..z w f.) z 0 0 "' 4 4 2 DISTANCE FROM VEIN (CM) Figure 36~ Alteration profiles of cobalt, lead, copper, barium, and rubidium concentration changes for samples from stope l-13E and the open pit. :if'.'/,- Vertical dashed lines divide the zones of lf>1; visible and cryptic alteration. 1~!!, ' ALTERATION PROFILE STOPE 113 TRACE ELEMENTS 32:,------r---:~------,,,,______-co

-2 0. 0. ... 2 z 0... < a: ... 1 z w Pb 0 .. z b 0 0

6 8 10 DISTANCE FROM VEIN (CM)

ALTERATION PROFILE OPEN PIT OP T.RAC E ELEMENTS

-:,; 0. a. a -z 40 0... < a: z... Co w 0 z 20 p 0 0

Rb o,-1--~--.1--....-----,----...... --....---,-,.-...---....--~---1 4 12 16 20 DISTANCE FROM VEIN (CM) 109

of unaltered and metasomatically altered rocks to calculate

gains and losses resulting from metasomatism. Gresens'

equation takes into account volume changes that may accom

pany metasomatic alteration. The equation was used to

compare results with the alteration profiles, to look at

averaged chemical trends, and to examine the overall chem

ical changes by comparing an average of unaltered samples

with the most intensely altered tonalite of the zone of

visible alteration. The Gresens' equation is as follows:

Xn = 100 ( Fv (gB/gA) CnB - CnA ) .

Where: Fv= Volume Factor, Fv>l Positive volume change ". Fv

gA= Specific Gravity of Rock A

gB= Specific Gravity of Rock B

CnB" Weight Fraction of Component n in Rock B

CnA= Weight Fraction of Component n in Rock A Xn'-' Amount of n Gained or Lost in Weight Percent

A total of nine visibly unaltered samples of the

light-phase tonalite collected in areas without veins were

averaged for use in the calculations. For each profile,

the chemical analyses of both the visibly altered and the

cryptically altered rocks were averaged. The unaltered

average was then used in the calculations with the four

different sets of data for visibly altered and cryptically

altered samples. Figure 37 shows the composition-volume diagram for 110

stope 1-13E comparing the unaltered average and the visible

alteration samples. Of interest is the intersection of the

curves with the gain-loss zero line. Immobile constituents

in metasomatic processes are shown as a cluster of points

on the gain-loss zero line. Assuming a volume factor (Fy)

at this point, in this case 1.00, relative losses and gains

can be determined with losses to the right and gains to the

left of the Fv value chosen. Constituents near the chosen

Fv value are assumed to be relatively immobile. u Results of Gresens' analysis are given in Figures 38 .. and 39. For each of the four vein profiles, three compar " isons were made. The first was between the unaltered rock

and the rocks of the zones of cryptic alteration, the

second between rocks of the zones of cryptic and visible

alteration, and finally the overall change between the

unaltered rock and the rocks of the zones of visible alter

ation.

Comparisons of Unaltered and Cryptically Altered Rock • (Figures 38 and 39, A and D) The zones of cryptic alteration are defined by dis

tinct increases in potassium, carbon dioxide, and calcium,

and distinct decreases of water and total iron. Slight

increases of manganese and sodium are also present, with

increases of phosphorous present in all but one profile.

In the zones of cryptic alteration there is an increase in

abundance of carbonate, decrease in chlorite, biotite, and

white mica, and the presence of more rutile than ilmenite. M" Jf-·d :· Figure 37: Composition-volume diagram (A) and graph (B) ii ' ";'j' for unaltered average and visible alteration !L' of stope 1-13E after Gresens (1967). ,,,. H.;,: jjR, jlk-, .~-

ii ' . ,it; . j jlffl_<. /;\.:~ :· 111··~ :· ;Jf ,.;. •IL :r, \&\.I, ' A. 4

CO2 2 cao

0 w O --- (:, z MgO < 20 :c 0 )( Fe203 Ill -2

"':::E < a: (:, ,,. -4 '!; ,, " -a

-a ' ' 0.6 0.8 1.0 1.2 1.4

VOLUME FACTOR (Fv)

CO2 Na Al CaMn L,TI S I p • • I • I I I . . 1.2 8. ·-1.0 o.e o.a 113

The occurrence of granophyric intergrowths tends to de crease in the zones of cryptic alteration, and simple quartz replacement of albite is more common.

Comparisons of Cryptically and Visibly Altered Rock (Figures 38 and 39, Band El Results of Gresens' analysis parallel the results of the alteration profiles. The zones of visible alteration have been produced by increases of sodium with slight increases of aluminum. Decreases of water and total iron, M ,; a major decrease of potassium, and a minor decrease of ',L •• silicon also characterize the zones of visible alteration. 1 :i, Compared to the zones of cryptic alteration, the zones of ' visible alteration have rare albite/quartz intergrowths and fresh albite is more abundant.

Comparisons of Unaltered Rock and Visibly Altered Rock (Figures 38 and 39, C and F) This comparison was made in order to study the overall effect of the alteration by comparing the unaltered parent rock with the most intensely altered wallrock. The overall changes include distinct increases of carbon dioxide, sodium, and calcium, with distinct decreases of total iron and water. Other trends are slight increases in manganese and slight decreases in magnesium and silicon. Potassium shows extreme depletions in 3 of the 4 profiles but shows definite enrichment in the other. Previous work reooqnized ~hQ introd~Qtion of sodium as a result of the hydrothermal veining (Blackburn and ~ 11,,·~i,,

·;:~. r 1111/. ' il4!C" ."it ·~ .. ·'11· ~ 1,

,\ ·~"

Figure 38: Composition volume graphs for stope l-13E and the open pit.

A: stope l-13E unaltered average and zone of cryptic alteration. B: stope 1-13E cryptic and visible alteration zones. C: stope l-13E unaltered average and zone of visible alter 'L' ation. D: open pit unaltered average and zone ,1;_ - of cryptic alteration. E: open pit cryptic ,, and visible alteration zones. F: open pit un ' altered average and zone of visible alteration. Numbers along horizontal axis represent different values for Fv• -GAINS LOSSES~

+-K CO 2 Tl SI 1 8 1,.,_.·..... M,_,,n:~ _.c_a____ ..,.f_____ N_~_:~~-'-A~·- __~.. ... _,__...,. ___ •H2o-+ 0.6 1.0 113 UNALTERED AVE. AND CRYPTIC ALT. K MOM Fe- Hlto:::::i 1 1 1 E3---""""----N•f..,...... 1. _._.1~.i...c_9_2_ ...__ t,.._ ...... 8S::! M W 1A 113 CRYPTIC AND VISIBLE ALTERATION

Fe Mb •~ CO2 Na Al c.a, ,Tl .s, P K MQ..e~. 0----.--·--·----·--·-"",,...---·..... ----- .....·---~:10 M W 1A 113 UNAL TEAED AVE. AND VISIBLE AL TERA TION

K NaSITI Al c.a Mn~\:'.L,Mg E;,e f o---d"'a-----~- ...----1 ... ~0-----,,-----1!"'4-- 0P UNALTERED AVE. AND CRYPTIC ALT.

_,;) E------M-·n...... 1\.a __ 'i_'_c_t ...t_r_~_g_]_'_t_,e ______~ 0.6 1.0 1.4 OP CRYPTIC ANO VISIBLE ALTERATION

Ca Na Mn Al SI MgTI K• F•f4 1!.. F------;·~·-----·-,..·---·--·-·,...----;M m 1A...... OP UNALTERED AVE. VISIBLE ALTERATION 116

11;:. ·,'' ' rlr"·"' ,,· JL··:.:;: Figure 39: Composition-volume graphs for stope l-05CW and 1c,:·: ·· the open pit. it;:' . A: stope 1-05CW unaltered average and zone of 111,, cryptic alteration. B: l-05C~ cryptic and ,~:..:• .- ,J visible alteration zones. C: 1-0SCW unaltered IL., average and zone of visible alteration. O: !•.',1 1: open pit 3 unaltered average ar.d zone of t~,.,_,: cryptic alteration. E: open pit 3 cryptic and visible alteration zones. F: open pit 3 un altered average and zone of visible alteration.

;,,;.: . Numbers along horizontal axis represent different values for Fv• -l-GAINS LOSSES-

K +-• Na Al cci2 c1~n ·Tl.,,\f~p1,Fa Hf~ A--r-----r---r------....-u w u 105 UNALTERED AVE. AND CRYPTIC ALT.

1 ~ f.1nC~2 ca.fi1!~l~ f11:Fa H20~ 8 0,6 1.0 1.4 105 CRYPTIC AND VISIBLE ALTERATION

CO2 H20 .._. Mn Na Tl. ....,. C . • • Fa• K• . M W 1A ,, 105 UNALTERED AVE. AND VISIBLE ALTERATION

CO2 :...: ca H20 o•K.Mn f Tt_~a \I \l~~Mg •-+

M W U '.;; OP-3 UNAL TEREO AVE. AND CRYPTIC ALT.

M_~V02 Fe Na::::::rr M.nf ~ .ca Hf O E--o.,~-s----,.1-----1.;,.o•Tf"1"""'...... """"T(---"""'-1""~-- 0P-s CRYPTIC AND VISIBLE ALTERATION .£92 (-"Mn H20 ·F(-•K .ca ..P Na• Tl • SI• Al • Mg· • Fe, ._,. & I & l & OP-3 'UNAL TEAED AVE. AND VISIBLE ALTERATION 118

Janes, 1983; Chisholm, 1951). The alteration types and

interpretations of chemical and mineralogical changes

associated with alteration will be discussed in Chapter 4,

section 3.

3.3 DESCRIPTION OF ORE MINERALS AND ASSOCIATED MINERALS

Two different generations of pyrite are present at Goldlund. The two are morphologically different, with the . • first generation consisting of fine-grained aggregates

and individual anhedral grains and the second euhedral

to subhedral cubic grains. The anhedral pyrite is dis

seminated throughout the altered zones and is occasionally

found in the unaltered host rock. The cubic pyrite is

,r generally found in the alteration zones and in the vein

itself. The cubic pyrite ranges in size from less than

1.0mm up to 16.0cm in long dimension.

The mineral associations of the two generations are

similiar, with the exception of the lack of gold,

petzite, and calaverite inclusions or segregation veins

within the anhedral pyrite. Anhedral pyrite is also

replaced by galena, but no replacement of the cubic pyrite

by galena was observed.

The cubic pyrite is highly fractured and is commonly

sealed with altaite and occasionally gold (Figures 41A and

41B). The cubic pyrite.commonly contains inclusions of

albite and quartz. The anhedral pyrite has irregular

...... 119

fractures, and altaite and occasionally gold are concen

trated around the periphery of the grains. Both types of

pyrite commonly have fractures sealed with carbonate and quartz.

In hand specimen the pyrite is extremely fractured and tarnishes to various shades due to exposure. The relation ship between the pyrite and the various other minerals will be discussed below.

Scheelite (CaW04)

Although scheelite at the Goldlund deposit was con sidered fairly common by Blackburn and Janes (1983), only minor amounts were observed. Scheelite was found in contact with pyrite, ilmenite, rutile, and a yttrium phosphorous mineral (xenotime). The subhedral to anhedral grains range from 20 to 60 microns in length. Figure 40A shows a subhedral grain in contact with ilmenite, possibly being replaced by rutile, and grains of xenotime. The grain is found in an albite and ankerite gangue. No scheelite was observed in the unaltered host rock.

Xenotime (YP04 ) Euhedral to anhedral grains of a yttrium phosphorous mineral are present in minor amounts of some of the gold bearing sections. The mineral has been tentatively

identified as xenotime based on its chemistry, habit, and mineral as-sociations. Commom mineral associates of xeno time listed by Palache and others (1951, p.690) and Deer 120 and others (1962, p.344) that are found at Goldlund include: monazite, rutile, apatite, and magnetite. Grain size ranges from a few microns up to approximately 50 microns. The xenotime was observed in direct contact with the following minerals in the altered zones: rutile, ilmenite, apatite, scheelite, monazite, altaite, pyrite, and other assorted gangue minerals. Figure 40B shows xeno time surrounded and partially replaced by altaite. Figure

40C shows a euhedral grain partially enclosed in a complex intergrowth of rutile and ilmenite.

Magnetite (Fe3o4 J i'W Magnetite is fairly common in the unaltered, light .. phase, albitized tonalite but is rare in the zones of cryptic and visible alteration. When present in the altered zones, magnetite occurs as small anhedral in dividual grains or aggregates commonly associated with ilmenite. Euhedral to subhedral magnetite is much more common in the unaltered host rock. Magnetite is found in the gangue of the altered zones in contact with ilmenite and anhedral pyrite. Magnetite borders and slightly embays the anhedral pyrite. Replacement of anhedral pyrite by magnetite was noted by Webb (1948).

Ilmenite (FeTi03)

Unlike magnetite, ilmenite is common in the altered zones of the light-phase, albitized tonalite. Ilmenite occurs as irregular grains interstitial to the gangue 121

minerals, sheet-like concentrations along the outside of

the veins, and with rutile in complex grains. Ilmenite is found in contact with the following minerals: rutile,

anhedral pyrite, scheelite, xenotime, and altaite. Rutile

appears to replace ilmenite along fractures (Figure 40A).

Figure 40C shows the complex intergrowth relationship

between ilmenite and rutile with this relationship common

in some gold-bearing sections. Ilmenite has also been

observed slightly embaying a 30 micron rounded bleb of

scheelite included in pyrite, and also surrounding,

slightly embaying, and replacing anhedral pyrite. '

In hand specimen ilmenite occurs as dark black streaks . ' ' and ribbon-like grains concentrated to the outside of the

veins or as minute grains within the alteration zones.

Ilmenite is common in gold-bearing sections; its associ

ation with magnetite is common in the unaltered host rock

but rare in the altered zones.

·'

Rutile is closely associated with ilmenite in the

altered zones. Occasionally rutile occurs as elongate

bladed grains within the unaltered host rock. Rutile

replaces ilmenite and is commonly in contact with it.

Rutile has also been observed embaying anhedral pyrite and

partially included within the anhedral pyrite.

Carbonates

Two types of carbonate are present in the altered, ' 122

light-phase, albitized tonalite. Both carbonates occur as distinct grains, fracture fillings, and fine-grained aggregates. Ankerite (CaFe(C03)2) and calcite (CaC03) occur concentrated along the vein walls as well as inter stitial to other gangue minerals of the altered zone. Both carbonates fill fractures in albite and other gangue minerals in the altered zones. In hand specimen ankerite is a light gray on fresh surfaces and weathers to a reddish brown, in contrast to the cloudy white color of calcite. Although both carbonates are present in the unaltered host rock they are more abundant in the altered zones with • the ratio of ankerite to calcite increasing nearer the veins. Ankerite is occasionally present in euhedral ,, rhombic-shaped grains up to 1.5mm in size and with common inclusions of albite and quartz. Calcite seals fractures in ankerite in a few samples, suggesting a later appearance of calcite in the paragenetic sequence.

Sphalerite (ZnS) Minor amounts of sphalerite occur at Goldlund, with up to 1 percent of iron-rich sphalerite occurring in certain areas (Blackburn and Janes, 1983). Sphalerite occurs as fine-grained, brown to dark yellow aggregates concentrated adjacent to the veins and occasionally along the inside of vein walls. Subhedral grains up to 400 microns were ob served in contact with cubic pyrite along the outside of a vein. Small anhedral grains are occasionally found scattered throughout the albite, quartz, carbonate gangue 123 of the visibly altered zone and in contact with pyrite.

Webb (1948) noted the occurrence of sphalerite with dis persed particles of galena.

Chalcopyrite (CuFeS2)

Chalcopyrite has only been reported in noticeable amounts in old ore zone #4 (Webb, 1948; Frohberg, 1952).

It appears to be only a very minor constituent in other ~,· ore zones.

Chalcopyrite occurs as scattered, generally anhedral and irregular grains found in the gangue of the zones of visible alteration. It is also associated with anhedral and cubic pyrite both in contact with and as small in ,,• clusions within the pyrite (Figure 40F). Chalcopyrite was • also reported occurring as remnant blebs in galena in the old ore zone #4 and was interpreted as an almost complete replacement of chalcopyrite by galena (Webb, 1948).

Galena (PbS)

Galena is present as a minor constituent in the high I grade sections. It appears to be concentrated in zones of visible alteration and only rarely in zones of cryptic alteration. Galena is commonly found replacing anhedral pyrite (Figure 40D), but has also been found included within and concentrated around anhedral pyrite with no apparent replacement. Galena replaces chalcopyrite as previously noted. Occasionally galena is visible in small, up to 1.0cm, irregular grains in hand specimen. 124

Petzite (Ag3AuTe2 ) The presence of petzite in high grade sections was first noted by Frohberg (1952). Petzite occurs as irregular to rounded inclusions within cubic pyrite (Figure

41B), and in compound grains along with calaverite, altaite, and native gold, The compound grains are included in cubic pyrite and also interstitial to the gangue minerals of the altered zones. Rounded blebs up to 40 , ! microns in diameter and irregular patches up to 40 microns • • in length are included in cubic pyrite from stopes l-27E ~t' ,, and 1-13E. No discrete individual grains of petzite were ~ ];' observed in the altered host rock, only grains included in pyrite or in compound grains with other tellurides. " '

TABLE 20

CHEMICAL COMPOSITION OF PETZITE

1. 2. 3. 4.

Au 25.42 23.53 24.33 23.69 Ag 41. 71 43.78 40. 70 41. 06 32.87 30.89 32.60 32.00 ,, Te " Fe 0.31 tr. Pb 0.36 0.07 Zn 0.05 Cu 0.09 Ni 0.04 s 0.03 Insol. 0.10 Total 100.00 99.08 97.63 96.92

1. Calculated for AgfAuTe2. 2. Average of 4 samp es from this study. 3. From Markham (1960, p.1168), analysis from Kalgoorlie, Australia. 4. From Thompson (1949, p.352), analysis from Huronian Mine, _Moss Township, Ontario. 125

Occasionally inclusions of petzite, calaverite, and altaite within the cubic pyrite are abundant enough to give the pyrite a mottled texture.

The ratio of Ag to Au in the samples of petzite from

Goldlund are slightly higher than calculated for petzite suggesting minor substitution of Ag for Au (Table 20).

Altaite (PbTe) Altaite occurs within the altered zones of the host •I 1 ',, rock and appears to be associated with native gold, ,,;1 petzite, and calaverite. Altaite is a common associate of "• l native gold in high-grade thin sections. Some thin sec I' tions contain abundant altaite with no apparent gold, ,, petzite, or calaverite. However when gold, petzite, or calaverite occur, altaite is always common. Altaite fills fractures in albite, quartz, and other gangue minerals in the altered zone and occasionally fills fractures in vein quartz. It is commonly found interstitial to the gangue minerals of the host rock, as veinlets, and as discrete grains.

Altaite has been observed in direct contact with the following minerals: pyrite, ilmenite, rutile, apatite, monazite, xenotime, petzite, calaverite, and native gold.

Altaite is generally concentrated to the outside of both generations of pyrite with occasional stringers extending out into the surrounding gangue. It also occurs as rounded and irregular blebs within. Altaite seals fractures within the cubio pyrite (Figures 41A and 41B) and has also been 126

found in segregation and replacement veins. It has been

found included as small, 10 to 30 micron, rounded and

irregular grains in both generations of pyrite and

occasionally forms a mottled texture. Altaite replaces

xenotime as seen in Figure 40B.

Altaite has also been found in compound grains with

petzite, calaverite, and native gold (Figure 41CJ. The ,, exact relationship between the tellurides and native gold I y in the compound grains is unknown but in one instance • 'j altaite appears to vein petzite (Figure 41C). In hand ' specimen, altaite is recognized by the cloudy, blue-gray

color that it imparts to enclosing quartz. An average

composition of altaite from Goldlund is given in Table 21.

TABLE 21

CHEMICAL COMPOSITION OF ALTAITE

1. 2. 3. 4.

Pb 61.91 61.00 61. 33 61. 26 Ag 0.87 0.43 AU 0.07 0.02 Cu 0.23 0.01 0.20 Fe 0.14 0.13 0.64 Te 38.09 37.46 38.43 36.84 Se 0.08 s 0.15 0.29 Zn 0.14 Insol. 0.46 Total 100.00 100.06 100.43 99.69

1. Calculated for PbTe. 2. Average of 3 samples from this study. 3. From,Markham (1960, p.1171), analysis from Kalgoorlie, Australia. 4. From Thompson (1949, p.362), analysis from Lake Shore Mine, Kirkland Lake, Ontario. 5' 127

Calaverite {AuTez)

Calaverite, previously undetected in the Goldlund

Mine, was observed numerous times. An average composition of calaverite from the Goldlund Mine is given in Table 22.

The associations of calaverite are very similiar to those of petzite, It occurs in various combinations with petzite, altaite, and native gold in compound grains, and as irregular and occasionally rounded grains within the cubic pyrite. In thin sections from stope 1-27E, calaver ite is more common than petzite as inclusions in the cubic pyrite, but of about equal proportions in samples from stope 1-13E. Generally the included grains in pyrite are less than 20 microns in size. Calaverite, unlike petzite,

TABLE 22

CHEMICAL COMPOSITION OF CALAVERITE

1. 2. 3. 4.

Au 43.59 42.21 41. 76 39.36 Ag 0.44 0.80 0.30 Te 56.41 56.48 56.64 54.32 Pb 0.23 5.20 Zn 0.02 Cu 0.13 0.24 Fe 0.31 0 .33 Co 0.03 s 0.12 Insol. 0.24 Total 100.00 99.85 99.20 100.11

1. Calculated for AuTe2. 2. Average of 4 samples from this study. 3. From Markham (1960, p.1166), analysis from Kalgoorlie, Australia. 4. From Thompson (1949, p.349), analysis from Lake Shore Mine,_Kirkland Lake, Ontario. With minor altaite. 128 was observed in the altered host. rock as irregular grains near the compound grains of tellurides and native gold

(Figure 41C). Compound grains ranged up to 300 microns in

length. Associations observed in the compound grains include: calaverite-petzite-altaite-native gold, calaver ite-altaite, and calaverite-petzite-altaite.

Native Gold (Au)

Gold has been found at many locations throughout the study areas but economic concentrations are very rare.

Samples of gold were observed in thin section from stopes l-27E, 1-13E, and also from the open pit. Gold has been observed associated with calaverite, petzite, and altaite in compound grains both in the gangue and within the cubic pyrite as mentioned above. It is found crosscutting

(Figure 40F) and concentrated to the outside and slightly replacing anhedral pyrite (Figure 40E). Gold occurs within cubic pyrite and as irregular grains which show replacement textures (Figure 410). It is also found concentrated to the outside (Figure 41E), and filling fractures within the cubic pyrite.

The highest concentrations of gold appear to be associated with the anhedral pyrite grains and irregular aggregates. Grains of irregularly shaped gold up to 300 microns in diameter were observed in contact with and slightly replacing pyrite (Figure 40E). Large grains of gold are.also common in the gangue surrounding the an hedral pyrite and irregular aggregates. 129

I .I I

Figure 40: Backscattered electron images of mineral to I mineral relationships. I A. Subhedral grain of scheelite (sch), with I xenotime (YP), and rutile (ru) after ilmenite (il). The dark surrounding areas are gangue. Bar scale represents 10 microns. I

B. Altaite (at) surrounding, embaying, and replacing xenotime (YP). The dark surrounding areas are gangue. The bar scale represents 10 microns.

C. Euhedral grain of xenotime (YP) partially enclosed in a complex intergrowth of ilmenite (light gray) and rutile (dark gray). Bright grain to the lower right is native gold. Bar scale represents 25 microns.

D. Galena (ga) surrounding and replacing early generation pyrite (py). The dark surrounding areas are gangue. Bar scale represents 10 microns.

E. Native gold (Au) surrounding, embaying, and replacing early generation pyrite (py). The dark surrounding areas are gangue. Bar scale represents 50 microns.

F, Native gold (Au) filling fracture and partially replacing early generation pyrite (py). Also, exsolution blebs of chalcopyrite (ccp) within the pyrite (py). The dark surrounding areas are gangue. Bar scale represents 10 microns.

Figure 41: Backscattered electron images of mineral to mineral relationships.

A. Altaite (at) filling cubic fractures and partially replacing late generation cubic pyrite. Bar scale represents 50 microns.

B. Altaite (at) filling fractures in late generation cubic pyrite. Also, rounded exsolution(?) grains of petzite. Bar scale represents 10 microns.

C. Compound grain of native gold (Au), petzite (pz), altaite (at), and calaverite (ca). The dark surrounding areas are gangue. Bar scale represents 50 microns.

D. Native gold (Au) included in and replacing late generation cubic pyrite. Bar scale •'*"'-·1111J1,J:' represents 10 microns. iiom·, 1 .-~;;:' !lllffk,< ••ti:·!· E. Native gold (Au) concentrated to the out ..1,;·1'. side and partially replacing late generation cubic pyrite (py). The dark areas are mainly quartz. Bar scale represents 25 microns.

133

Gold is usually concentrated in the zones of visible

alteration but may also be found within the vein. Gold was

otserved in hand specimen filling fractures up to 0.2cm

wide within vein quartz. Gold is also found sealing

fractures in quartz, albite, ankerite, and calcite within

the zones of visible alteration. Gold is always found

associated with altaite but the inverse is not always true.

Gold also appears to be intimately associated with petzite

and calaverite although the exact relationship is unclear.

The gold of the Goldlund Mine occurs in solid solution

with silver. The atorr. percent of all samples probed

ranges from Au97Ag3 to AuggAg12. An average composition of

gold from the Goldlund Mine is given in Table 23.

TABLE 23

CHEMICAL COMPOSITION OF NATIVE GOLD

Au Ag Te Zn Cu Fe Co S Total 93.18 6.17 0.20 0.07 0.17 0.15 0.03 0.05 100.02

* Average of 4 samples from this study (Weight Percent).

f CHAPTER 4

INTERPRETATION AND DISCUSSION

4.1 GENERAL GEOLOGY

Metavolcanic and metasedimentary rock types delineate specific geologic processes that have been important in the study area. Pillowed lavas are common and indicate sub aqueous extrusion of lava. A southwest to northeast trending zone of acidic to intermediate pyroclastic rocks is located just to the south of the mine area (Figure 4), indicating explosive volcanic activity. Rock types present in the zone include: lapillistone, lapilli-tuff, crystal lithic tuff, breccia, tuff-breccia, and agglomerate (Page and Christie,-1980). To the east, iron formation, gray wacke, and other rnetasedimentary rock units of the

Minnitaki Group are exposed.

Page and Clifford (1977) concluded that a vent complex or a composite cone facies was located about 20km northeast in the Minnitaki Lake area within the Central Volcanics.

They based their conclusion on clast size variation in fragmental units and the presence of lithologies with proximal relationships to a source vent such as vesiculated dikes, air-fall bombs, and cored bombs. Similarly, in the Crossecho Lake area, the presence of varied clast sizes from 64.0mm suggests a location close to a vent complex. More field evidence is needed in order to demon strate the location of such a vent complex.

134 135

The relationship between volcanism and plutonism

during the Kenoran Orogeny is unclear. Langford and Morin

(1976) suggested that the late granites may be a contin

uation of the magmatic activity that produced the

volcanism. Various stocks within the Wabigoon Subprovince

have been dated using Rb/Sr methods. The Burditt Lake

Stock has been dated at 2598 +-45my and the Taylor Lake

Stock at 2640 +-3lmy (Birk and McNutt, 1977).

Numerous tectonic models have been proposed for the • formation of the Superior Province. Specific models have

been used to explain structural, lithological, and chemical

features of the western Wabigoon Subprovince (Blackburn,

1980; Trowell and others, 1980).

Local structures at the Goldlund Deposit are related

to major regional features of the western Wabigoon Sub

province. The Little Vermilion Fault is located just to

the north of the mine area, and several slips and minor

faults have been reported in the mine area itself (Froh

berg, 1952). Minor shear zones are also present. Chisholm

(1951) and Frohberg (1952) concluded that the fractures in

the albitized tonalite dikes were formed by regional

tensional forces. The formation of faults, shear zones,

and fractures due to regional as well as local forces have produced conduits for a fluid circulation system. This

system has allowed for the movement of the ore-bearing

fluids through the rocks with eventual deposition of gold in fractures in the albitized tonalite dikes. 136

Archean gold deposits are thought to have formed under deep-seated conditions with relatively high pressures and temperatures, 200-500 • C and depths of 1200m up to 15000m

(Colvine and others, 1984; Evans, 1980). Kelly and Goddard

(1969) list relative abundances of telluride minerals in selected gold mining districts. Kalgoorlie, Australia and

Kirkland Lake, Ontario are two Archean deposits that are listed. Although their mineralogy is much more complex than Goldlund's, the relative mineral abundance of common telluride minerals is similiar. The deposits have been classified as mesothermal-hypothermal and mesothermal

(metamorphosed volcanic?) respectively. Although more than one classification has been suggested, Kelly and Goddard

(1969) state, "Although these different classifications imply a very different sequence of events in the history of the ores, both would call for epigenetic emplacement of the ores to their present sites and for formation of the present mineral assemblages under high P-T conditions in a deep-seated environment."

Markham (1960) distinguished between low-temperature and pressure Tertiary telluride deposits and high-temper ature and pressure Archean deposits based on differences in mineralogy. Kelly and Goddard (1969) summarized the diff erences which are listed below. The deep-seated Archean deposits are characterized by abundant native gold; rare uncombined, tellurium; predominance of calaverite over krennerite; and common tellurides of lead, mercury, copper,

,' 137 and bismuth. The Tertiary deposits are characterized by abundant native tellurium; rare free gold; predominance of krennerite over calaverite; and rare base-metal and other tellurides.

Rock types of the Goldlund Mine area indicate wide spread volcanic and later plutonic activity. Similiar telluride mineral assemblages to those of Kalgoorlie and

Kirkland Lake suggest that gold in the Goldlund Mine area was also epigenetically emplaced late in the sequence of events at elevated pressures and temperatures under deep seated conditions.

4.2 COMPARISON ANO PETROGENESIS OF INTRUSIVE ROCK TYPES

Based upon geochemical and petrographic evidence the

Crossecho Stock, quartz-feldspar porphyries, and the quartz monzonite stock appear to be genetically related to one another but unrelated to the dark- and light-phase, albitized tonalite dikes. Webb (1948) concluded that the porphyry and albitized tonalite dikes were genetically related to the Crossecho Stock. He also concluded that both were differentiates from various depths of the same magma source from which the Crossecho Stock arose. Frac turing tapped the magma source with subsequent intrusion of the tonalite dikes and the partially differentiated por phyry dikes. Geochemical evidence supports the relation ship suggested between the quartz-feldspar porphyries and the Crossecho Stock, but the albitized tonalite dikes 138 appear to have formed from a different magma source. The relationship between the quartz porphyry mass and dikes and the other intrusive rock types is unknown. The highly sheared quartz porphyry mass and the unsheared dikes may be totally unrelated. Genetic relationships between the various rock types can be seen on an AFM plot (Figure 42A). There is a definite trend of increasing alkalies from the quartz monzonite stock through the quartz-feldspar porphyries to the Crossecho Stock. The albitized tonalite dikes plot closer to the total iron corner, separate from the previous group. The dark-phase, albitized tonalites generally plot closer to the total iron corner than the light-phase, albitized tonalite. Figure 42B shows a calc-alkaline trend for the Crossecho Stock, quartz-feldspar porphyry, quartz monzonite stock group, while the plot of albitized tonalite dikes is similiar to that of a trondhjemitic rock suite.

Figure 42C supports the possible calc-alkaline trend of the stocks and porphyries. Figure 42C also shows the grada tional increase in quartz relative to albite going from the light- to the dark-phase, albitized tonalites.

Pearce and Norry {1979) used Ti, Zr, Y, and Nb con centrations to examine variations in volcanic rocks to determine their petrogenetic relationships. Ti, Zr, Y, and

Nb were used because of their high charge/radius ratio.

Because of this property the elements are not readily carried in aqueous fluids and remain relatively unaffected 139

Figure 42: AFM, K-Na-ca, and Q-Ab-Or plots of the intrusive rock types.

A. AFM plot with A=NazO+KzO, F=Fe0+0.8998 (Fez03), M=MgO, all in weight percent. The diagram is divided into tholeiitic (Th) and calc-alkaline (C) fields after Irvine and Barager {1971).

B. K-Na-Ca (potassium, sodium, calcium) plot. The curves show trends for calc-alkaline (Cl and trondhjernitic (Tl suites (Barker and Arth, 1976). c. Q-Ab-Or (normative quartz, albite, and orthoclase) plot. The arrows show the generalized paths of calc-alkaline (C) and trondhjemitic (T) trends (Barker and Arth, 1976).

•- Crossecho Stock

o- Quartz-feldspar Porphyries

+- Quartz Monzonite Stock

•- Dark-Phase, Albitized Tonalite o- Light-Phase, Albitized Tonalite

•- Monzodiorites

6- Quartz Porphyry Dikes F A. .. ..

Q C. 141

by metasomatic alteration. In addition, these incompatible

elements are ideal for determining possible genetic re

lationships between various intrusive rock types. Rubidium

and strontium are commonly used to discriminate various

igneous rock types with similiar mineralogy and chemistry.

Again, the incompatibility of the elements aids in determining possible genetic relationships.

Results of the various comparisons show two distinct

suites of rocks and are given in Figures 43A-D. One group

consists of the albitized tonalite dikes, while the other

consists of the Crossecho Stock, quartz-feldspar porphy

ries, and the quartz monzonite stock. Both major and trace

element chemical data indicate that the two groups have

formed from different magmas.

Crossecho Stock- Quartz-feldspar Porphyries ' Quartz Monzonite Stock

In order for a fractionation trend to be correctly

identified, it should be consistent on all major variation

diagrams (Pearce and Norry, 1979). Figures 43A-D show

consistent fractionation trends from the intermediate

quartz-feldspar porphyries and quartz monzonite stock to

the acidic Crossecho Stock, supporting the concept of a

genetic relationship. Chemically and mineralogically

the rock types are very similiar. The quartz-feldspar

porphyries are homogeneous (Table 18), and are also

similiar in composition co the quartz monzonite stock samples (Table 17). Texturally and mineralogically the 142

Figure 43: OQserved fractionation trends on Rb-Sr (A), Ti-Zr (B), Nb-Zr (C), and Y-Zr (DI diagrams (Pearce and Norry, 1979). The trend arrow on diagrams B through D represents a general increase in Si02.

•- crossecho Stock

c- Quartz-feldspar Porphyries

+- Quartz Monzonite Stock

•- Dark-Phase, Albitized Tonalite

o- Light-Phase, Albitized Tonalite

' I • Z3-7 I A • B ,µ_,3-4 100 .o Z2-6~ ... Z2-8 -111, 0 f ~+ ,....-ill . .. .:0 E • Oo -Q, • .S- 10 0 .1 ,, Z3-4~• Z2-6 a: 0.,.. di d!-zs-7 <>-z2-9 0 61 0

1 o.o 10 1000 ,10 100 1000 Sr (ppm) Zr (ppm)

C D lo 100 ZS-4 ZS-7~Z2-e 100 z2-6-o o

Z3-4...:!' ZS-71' -e E Q. -Q, 'j> 2-9 Q, z2-e ,.. ,S-... 10 .. ll: ~ 10 ••

,f: 'LO~--lL.....J...WU.Llf10~0~--=-.,_...... _~1~0~00 ,0 100 1000 Zr (ppm) Zr (ppm) 144 quartz monzonite stock and the Crossecho Stock samples are also very similiar (Table 12).

The quartz monzonite stock and the quartz-feldspar porphyries appear to be derived from early liquid fractions from the original Crossecho Stock magma chamber. Magma may have been tapped from the top of the magma chamber by fracturing forming the dikes and an offshoot intrusion, the stock, as suggested by Webb (1948). The Crossecho Stock represents a later pulse of magma which formed the core of the main intrusion.

Figure 44 a Harker variation diagram showing the relationship between the rock types. General trends ex pected during the intrusions of granitic plutons in the

Superior Province are towards increasing K20 and Si02 contents, with decreases in Na2o, Cao, MgO, and total iron with occasional exceptions (Price and Douglas, 1972).

Increases of K20 and decreases of Na20, Cao, MgO, Ti02,

P205, and total iron occur with increased Si02 content in the stocks and porphyries, suggesting magmatic evolution from the intermediate quartz monzonite to the late

Crossecho Stock granite (Figure 44). Corresponding trace element trends include increasing Rb and Nb and decreasing Zr, Ti, and Sr concentrations (Figure 43).

Albitized Tonalite Dikes

Plots of the albitized tonalite dikes on a QAP diagram

(Figure 16) show considerable variability for both the dark and light phases. Although the rock type is fairly

'!" I \ I I ( ! l [ Figure 44: Silica-variation (Harker) diagram of the ' Crossecho Stock- Quartz-feldspar porphyry and.Quartz Monzonite Stock rock series. •- Crossecho Stock I o- Quartz-feldspar Porphyries I +- Quartz Monzonite Stock i I r l ( t ( I l 17- • .., 0 • 0 ~ 16· • 0 -

4e • 0 • N 3c :.: + 2, 0 0 • • - 0 + 0 •

~ 0 7• 0 N 0 0 • QI • • z s~ 0 0 • + • • y + 0 0 0 <> a, 1• - :I! .. • - .., ~ 0 } 2• ... - lo + 0 u. -• + 1• • 0 - .. ,f - - 41- 0 0 0 + - i l'L 31-; - • • 2~. •

~ 0 0 so.: 0 - + - o. 2• . • • ... 0.1~ - - /!Jo. 2 + y - + .r'o.11- 0 • • . • . ." . • . -. 6 2 64 <>O fU 1'4 Per Cent S102 - 147 homogeneous chemically (Tables 10 and 11), the amount of biotite and carbonate varies considerably (Tables 6 and 8).

The potassium in the biotite and the calcium in the carbon ate effect the CIPW normative mineralogy by increasing the normative orthoclase and anorthite. Such samples plot on the QAP diagram in fields with common potassium feldspar even though potassium feldspar is absent. The lack of potassium feldspar and the abundance of plagioclase imply a tonalitic rather than a granodioritic composition as sug gested by Webb (1948), Chisholm (1951), and Armstrong

( 1951).

The degree to which the tonalite dikes have been changed mineralogically and/or chemically from their original state is not known. The granophyric intergrowths appear to be an original component of the dikes. Alter ation profiles show slight desilicification suggesting that the intergrowths were present originally and have slightly broken down during metasomatic alteration rather than formed as the result of it. The granophyric intergrowths are interpreted to be an original crystallization product.

Later, minor replacement of albite by quartz formed the observed replacement intergrowths.

Whether potassium feldspar was at one time present in the dikes and has since broken down is unknown. Frohberg

(1952) reported the presence of orthoclase in the dikes but no supporting microscopic evidence was f.ound. The plagioclase of the dikes ranges in composition 148 from pure albite to An 6 _6 • The presence of albite rather than oligoclase or andesine in a tonalite is atypical.

Increasing sodium contents near veins suggest the addition of sodium from the veins into the dikes and subsequent albitization.

It is concluded that the original tonalite has undergone albitization due to the metasomatic introduction of sodium. More ca-rich plagioclase such as oligoclase has been replaced by albite. The liberated Ca was removed or combined with CO2 to form carbonate.

Granophyric intergrowths occur in both the dark- and light-phase, albitized tonalite dikes. Hughes (1972) noted occasional plagioclase nuclei upon which the inter growths form. He also noted the presence of granophyric intergrowths with no apparent nuclei. Both types are present in the albitized tonalite dikes. Barker (1970) noted that albite in granophyric intergrowths is commonly untwinned. Texturally the intergrowths are granophyric but have only a minor potassium content. Chemically, they closely resemble Barker's (1970) description of graphic granite but do not have the well-defined texture that he described. Barker (1970) concluded that granophyric inter growths may be polygenetic, possibly explaining the presence of crystallization- and replacement-type inter growths in the dikes and the textural gradation between them. The.intergrowths are unusual in that they resemble 149 granophyric intergrowths of K-feldspar and quartz in form but consist of albite and quartz. The origin of the inter growths is unknown.

Based on their similiar chemistry and mineralogy, the dark- and light-phase, albitized tonalites are interpreted to be phases of the same rock unit. In certain samples both the dark and the light phases are nearly identical chemically and mineralogically, while in others chemical gradation from one phase to the other is common.

Trace element concentrations of samples from the ton alite dikes of ore zones #2 and 13 plot separately from the main dike samples of ore zone #1 and the east extension

(Figures 43B-D). The dikes of ore zones #2 and #3 have lower Y, Zr, and Nb concentrations and higher Ti02 con tents. The light-phase dike of ore zone #2 has higher Sr concentrations compared to the other samples of the light phase, while the dark-phase samples of ore zone 13 have higher Sr and generally lower Rb concentrations compared to the other dark-phase samples (Figure 43A).

Such data supports the suggestion made in section 2.3 that the dike of ore zone i2 may be an extension of the dike of ore zone #3. The reason for·variable trace element concentrations between the dikes of ore zones #2 and i3 and the main dike is unknown. The exact mode of formation of the albitized tonalite dikes is also unknown. Barker and Arth (1976) proposed a model for the formation of an andesite-free bimodal trond- 150

hjemitic-basalt suite of Archean gneisses. Barker and Arth

(1976) state that, "trondhjemitic-tonalitic liquids are

polygenetic in origin: they may form by crystal fraction

ation of less siliceous, more mafic liquids under either

dry or relatively wet conditions; or they may form by

partial melting of basaltic parents of eclogitic, amphib

olitic, or gabbroic rock types." Barker and Arth's model

for the formation of tonalitic liquids by partial melting

includes the following stages: mantle upwelling and

-""' - formation of a thick volcar.ic pile, metamorphism to amphib

olite in the lower portions of the pile, partial melting of

the amphibolite forming trondhjemitic/tonalitic liquid, and

intrusion and/or extrusion. The albitized tonalite dikes

fall into Barker and Arth's low Al203 (<15%) category.

Barker and Arth's (1976) model may be used to explain the

formation of the albitized tonalite dikes. It is inter

preted, accepting the above model along with field rela

tionships, that the dikes magma was derived from partial

melting of the surrounding Keewatin Volcanics. The Cross

echo Stock, quartz-feldspar porphyries, and the quartz

monzonite stock are interpreted to have been intruded into

the supracrustal assemblages during active plutonism of the

Kenoran Orogeny.

4.3 ALTERATION

Numerous types of hydrothermal alteration are observed

associated with the gold-bearing veins of the Goldlund Mine. Alteration profiles, composition-volume graphs, and 151 thin sections indicate the following types of alteration: albitization, carbonatization, slight desilicification, pyritization, and slight dehydration. A schematic summary of the processes is given in Figure 45. Boyle (1979) clas sifies and defines the various types of alteration associ ated with gold-bearing veins of epigenetic gold deposits.

Feldspathization

Alteration profiles, composition-volume graphs, and thin-section evidence suggest that sodium was added to the altered wall rock, forming albite.

Albitization may result from the liberation of calcium and subsequent concentration of sodium after the alteration of plagioclase, or by metasomatic introduction of sodium

(Barnes, 1967}. Geochemical evidence indicates that, at

Goldlund, sodium has been metasomatically introduced causing the conversion of most aluminous material to a sodium-rich plagioclase ranging in composition from pure albite to calcic-albite as predicted by Barnes (1967).

Carbonatization

The association of carbonates and gold and the importance of CO2 and other volatiles in the formation of gold deposits are discussed in Kerrich and Fyfe (1981).

At Goldlund, ankerite and calcite are both products of the alteration, with ankerite more common. Brown (1985} noted the 2- to 3-phase co2-rich inclusions in vein quartz from Goldlund. This observation, along with l I I

\ I '

Figure 45: Simplified schematic summary of chemical and mineralogical changes associated with alteration. Dashed boxes indicate mineral(s) that are broken down, with solid boxes I indicating minerals formed as a result of metasomatism. Arrows indicate direction of element migration. I VEIN ALTERED ZONE

ADDITION Fa, Mg, Mn CARBONATES C02~--;,1

ADDITION Ca, -Mn Fe~L_JMn Mg_____ .. 1 .... 1---1 CHLORITE z r . I • 1-K .. I IRON I I BIOTITE, I :i. ... )ox1DES.f [!:•.:.Me_~':;~!_Tesj-AI L ___ ...J BREAKDOWN -r Si

ADDITION·s,--.;,,i PYRITE

ADDITION Na---1.--...... i Al BITE QUARTZ ·\TJ_L_, I QUARTZ, .ALBITE, I I ANO l--+Ca I INTERGROWTHS l L------..J BREAKDOWN/· RECRYSTALLIZATION 154

the profiles and composition-volume graphs, suggests that

a co2 -bearing fluid introduced CO2 and minor amounts of calcium and manganese into the wall rock forming carbon

ates. The zones of alteration at Goldlund are character

ized by a high CO2 content, abundant albite and carbonate,

and lack of chlorite and biotite.

The nearly total absence of chlorite in the zones of

alteration suggests a breakdown of chlorite and possibly

biotite. Liberated Fe, Mg, and Mn were bound in ankerite with excess iron taken up in the formation of pyrite,

similiar to what was proposed by Boyle (1979) for the

Yellowknife area and by Bateman (1940) for the Uchi gold

area. Calcium from plagioclase also contributed to the

formation of carbonate. Webb (1948) and Frohberg (1952)

suggested the presence of more Ca-rich plagioclase before alteration. With the breakdown of chlorite, liberated Si02 and Alz03 most likely combined to form albite, with excess SiOz migrating to the vein and crystallizing as quartz.

Desilicification

Alteration profiles and composition-volume graphs

show a slight desilicification of the wall rock. Loss of

silica within the altered wall rock is consistent with carbonatization where SiOz is released by the breakdown of amphiboles, pyroxenes, and feldspars (Boyle, 1979).

Boyle (1959) noted the extensive depletion of Si02 in the altered zones of the Yellowknife Goldfields of the

Northwest Territories and concluded that it was caused by 155

vertical and lateral secretion of Si02. This is believed

to be what happened at Goldlund on a much smaller scale.

The visibly altered wall rock shows slight depletion of

Sio2 • The scarcity of granophyric intergrowths may be a result of the alteration and cause of the depletion. The

Sio2 from the intergrowths and plagioclase may have been liberated and formed fresh albite and/or migrated to the

veins and crystallized as quartz.

Pyritization

At Goldlund iron has been depleted in the zones of

alteration. It is interpreted that iron and some magnesium have been liberated by the breakdown of chlorite, biotite, and Fe-oxides in the zones of alteration and have migrated

to form pyrite and ankerite both in the veins and in the

zones of alteration, similiar to what was proposed by Hurst

(1935) for Porcupine, Ontario. At Goldlund alteration profiles show dramatic increases in sulfur in the zone of visible alteration. The introduced sulfur has combined with the liberated iron to form pyrite.

Other Alteration Effects

Alteration profiles and composition-volume graphs show

that the zone of visible alteration has been dehydrated.

Hydrated minerals such as sericite and chlorite are scarce.

The introduction of Pb into the wall rocks accounts for the

increased abundance of alkaite and galena in the zones of alteration. Introduced Cu and Zn account for the chalco- 156

pyrite and occasional sphalerite present. The high concen

trations of barium just outside the zone of visible alter

ation are suspected to indicate a concentration of a

barium-bearing mineral ls) such as barite.

The relationship of the different alteration types is

not clear. It is speculated that albitization was an early

event followed by and overlapping with carbonatization.

Pyritization appears to have been the last event, over

lapping with carbonatization. The relative positions of

desilicification and dehydration are unknown. Carbonate

was observed interstitial to secondary albite and both

secondary albite and carbonate were veined by gold, The

replacement of both generations of pyrite by gold and

tellurides and exsolution textures between the late generation, cubic pyrite and geld suggest that pyritization occurred before and during gold and telluride deposition

but not after.

It is interesting to speculate on why certain types of alteration, which are generally common in epigenetic gold deposits in intermediate host rocks, are absent at

Goldlund. The lack of abundant water in the veins and

subsequent depletion of water in the altered zones appear

to be the main reasons for the the lack of hydration,

sericitization, and chloritization. It is possible, how

ever, that chloritization and sericitization had taken

place as an early stage of alteration which is now partly

obscured by later events. Robert and Brown (1984) con-

' 157 eluded that a second metasomatic alteration was super imposed upon ar. earlier event at the Sigma Mine, Quebec.

This was based on inclusions of early alteration products within the alteration products (pyrite) of the later event.

Such inclusion of sericite and chlorite within the alter ation products of the wall rock are absent at Goldlund, suggesting that if earlier events of sericitization and chloritization had taken place they are not related to the gold-forming event.

Arsenopyritization is a common type of alteration associated with numerous gold deposits (Boyle, 1979).

Arsenic is usually metasomatically introduced and combines with introduced sulfur and either liberated or introduced iron. At Goldlund arsenic concentration generally de creases as the vein is approached, indicating that arsenopyritization has not occurred.

4.4 MINERAL PARAGENESIS OF ORE-BEARING AND ASSOCIATED MINl':RALS

The paragenesis of the ore-bearing and associated minerals for the Goldlund ore is given in Figure 46. The figure is based on detailed microscopic observations between various mineral phases. Where direct evidence of age relationships was absent, their order in the sequence was determined by the usual paragenetic position in gen eralized sequences from Edwards (1954, p.136), Ramdohr

(1980), and Boyle !1979, p.416). As-noted in Chapter 3, there are at least two gener- 158

.,:, ,·:

Figure 46: Generalized paragenetic sequence of ore bearing minerals, including xenotime, in the Goldlund Mine veins.

Solid Line- based on observation.

Dashed Line- tenative position.

Question Mark (?J- relationship unclear at this point.

,,, ; ··'$:itWW'#'',jc:. ,.... • ""- ·• I f'''i'f'II

TIME EARLY LATE

PYRITE !

SCHEELITE ------

XENOTIME

MAGNETITE ---t-----

ILMENITE

SPHAI.ERITE

CHALCOPYRITE

GALENA

RUTII.E !------?

Al TAITE ?-

PETZITE

CALAVERITE

GOLD 160 ations of pyrite. The earlier generation consists of anhedral grains and aggregates that do not include gold, petzite, or calaverite. The later generation consists of euhedral to subhedral, cubic, auriferous pyrite whose crystallization appears to have slightly overlapped with the introduction of gold and the tellurides. The formation of euhedral crystals generally implies early and un obstructed growth. Pyrite is an exception, forming as euhedral crystals regardless of its position in the para genetic sequence (Craig and Vaughan, 1981). The position of magnetite in the paragenetic sequence is unclear. The scarcity of magnetite in the altered host rock and the geochemical evidence of depletion of total iron in the zones of alteration are interpreted, in part, as being caused by the breakdown of iron oxides, partic ularly primary magnetite. Both the author and Webb (1948) have observed that secondary magnetite has embayed and replaced early anhedral pyrite, suggesting that it formed simultaneously with the other ore minerals in the sequence. Rutile was placed after ilmenite in the paragenetic sequence, although it may have formed much later as the result of oxidation of ilmenite. The process of pyriti zation of the wall ro.cks o.f metalliferous veins may cause the fo.rmatio.n o.f rutile after ilmenite (Ramdo.hr, 1980). The breaking do.wn o.f ilmenite causes the release of iron which is used in the formation of pyrite, while the released titanium is used in the formation of rutile.

'.,., 161

Another possible explanation for the formation of rutile is the oxidation of primary ilmenite. Haggerty

(1976) describes in detail the stages of oxidation of primary ilmenite and the subsequent formation of rutile.

The rutile/ ilme.ni te intergrowth-type grains resemble the photos presented by Haggerty (1976, fig. HG-7 and 8) and possibly are the result of a similiar oxidation process.

In the paragenetic sequence there is a distinct change in mineralization from an early oxide-sulfide stage, through a dominantly sulfide stage, and concluding with a late telluride and native gold stage. There is a general progression from early-formed, high-temperature minerals such as scheelite, to later, lower-temperature minerals such as the.tellurides. This suggests both changing fluid compositions as well as decreasing temperatures. The end of the formation of cubic pyrite slightly overlaps the beginning of the telluride-gold stage mineralization as indicated by both exsolution and replacement textures and will be discussed below. Altaite crystallized somewhat longer than petzite and calaverite.

Gold in Pyrite

Gold is commonly found associated with pyrite in numerous deposits (Springer, 1983). Native gold, petzite, and calaverite were all found included in the later gener ation of cubic pyrite as small, rounded exsolution blebs.

Early, high-temperature pyrite and arsenopyrite take in gold and silver in solid solution or as layers on growing 162 faces of crystals (Boyle, 1979). Upon cooling, the foreign constituents distort the crystal structures with a sub sequent rise in free energy of the crystal. Energy is dissipated by migration of the gold and other constituents to low chemical potential sites such as fractures and grain boundaries where small crystals form. This mechanism may explain the concentration of native gold and altaite along grain boundaries and in segregation veins (fracture fillings) of the cubic pyrite.

The presence of both exsolution and replacement textures in the cubic pyrite indicates the following sequence: 1) simultaneous deposition of gold .and tellurides with cubic pyrite, 2) termination of pyrite deposition and mechanical fracturing of pyrite, and 3) continued gold and telluride deposition in the fractures, cleavage fractures, and along grain boundaries of pyrite. Gold is associated with both generations of pyrite and is concentrated along the boundaries of the grains and occasionally fills fractures. Replacement of both gener ations of pyrite by gold is quite common. Colvine and others (1984) concluded that pyrite and other sulfides react with gold-bearing solutions and cause the precip itation of gold. The principle sites of gold deposition are commonly the pre-existing hydrothermal pyrite and other sulfides. At Goldlund this appears to be the mechanism responsible for the concentrations of gold along the grain boundaries of the early pyrite and also for some of the 163

concentrations of the later cubic pyrite. Gold was most likely carried by bi-sulfide or chloride complexes and was subsequently precipitated by contact and reaction with pyrite.

Petzite and Calaverite Numerous synthetic phase relationships have been worked out for the Au-Ag-Te system by Markham (1960) and Cabri (1965). Figure 47 shows their ternary diagrams for the Au-Ag-Te system and the corresponding tie lines for the

0 0 , 300 C and 290 C isotherms. Both studies conclude that petzite (Ag 3AuTez) and calaverite (AuTez) are commonly associated over a wide range of temperatures. Markham (1960) noted the compatibility of petzite and calaverite with a gold-rich alloy of composition Au93Ag7 to Aue9Agll (atom%) at 300• C. Gold samples probed from Goldlund ranged in composition from Au97Ag3 to Au9eAg12 (atom%), suggesting a temperature fairly close to 300°C for deposi tion of petzite, calaverite, and native gold. Figure 47 thus shows possible tie lines for the Goldlund Deposit. The reason for the absence of hessite is unknown, and

0 sylvanite is incompatible with a gold-silver alloy at 300 C (Markham, 1960). Both at Kalgoorlie, Australia (Markham, 1960) and Boulder County, Colorado (Kelly and Goddard, 1969), it was concluded that the tellurides and gold were late-stage phases formed at lower temperatures. 164

Figure 47: Relationships in the synthetic Au-Ag-Te system (from Kelly and Goddard, 1969, p.134).

A. 300°C isotherm of the synthetic system Au-Ag-Te (from Markham, 1960, p.1156). B. 290°C isotherm of the synthetic system Au-Ag-Te (from Cabri, 1965, p.1572).

Abbreviations:

Ca- calaverite Sv- sylvanite Pz- petzite Hs- hessite 300° C . A. MARKHAM. 1960 Te

Au~ Ag

IO 20

290° C B. CABRl, l965 166

4. 5 GENERALIZED MODEL OF GCLD D.EPOSITION FOR THE GOLDLUND DEPOSIT

Based upon physical, chemical, and mineralogical evidence, a generalized model of gold deposition can be proposed for the Goldlund deposit. The model includes various stages of development. These stages are:

1) Widespread volcanic activity formed a thick volcanic pile with metamorphism to amphibolite grade in the lower portions of the pile. Partial melting of the amphibolite formed a tonalitic magma which was intruded and formed the tonalite dikes;

2) Regional metamorphism and deformation increased the thermal gradient of the area and formed fractures in the tonalite dikes;

3) Intrusion of the Crossecho Stock and associated rock types liberated volatiles and water which mobilized metals and other constituents from the surrounding volcanics and sediments. Metamorphic secretion with migration of COz, s, and metal-rich fluids to the fractures in the tonalite dikes, which acted as conduits for the fluids;

4) Metasomatic exchange between the ore-bearing fluids and the tonalite dikes with subsequent alteration;

SJ Vein formation and precipitation of gold and metals due to changing fluid composition and falling temperatures.

Volcanic'Activity and the Formation of Tonalite Dikes

The formation of the tonalite dikes is discussed in

Chapter 4, section 2. 167

Regional Metamorphism and Deformation

Regional metamorphism increased the thermal gradient of the area while regional deformation affected the rocks of the area in different ways. The Keewatin volcanics and associated sediments responded in a ductile way to the tensional forces which resulted in schistosity and occasio nally shearing. The quartz porphyry mass west of

Franciscan Lake is sheared at N40 " E to N55 " E, most likely due to the same forces. The tonalite dikes, because of their superior competency, responded brittlely forming dilatant zones, tension fractures, or tension gashes. This process is called ground preparation by Marmont (1983).

Frohberg (1952) and Chisholm {1951) noted the occurrence of the same fr?cture pattern over many miles and both concluded that the fracture patterns are the result of regional forces.

The difference in competency between the tonalite dikes and the surrounding volcanics led to the formation of the fracture system. At Goldlund the veins rapidly dimin ish and the associated alteration haloes decrease in width and slowly disappear as they cross the contact between the albitized tonalite and volcanics and enter into the volcanics. Similiar field evidence was cited by Marmont

(1983) as supporting the structural principle of ground preparation. Gorman and others {1981) concluded that because of their competency, albitized felsic intrusions are structurally ideal host rocks for gold mineralization 168 regardless of the ultimate source of gold.

Intrusion of the Crossecho Stock and Associated Rock Types

The onset of the Kenoran Orogeny and the intrusion of granitic masses. into the volcanic and sedimentary sequence, such as the Crossecho Stock, acted as a heat engine, releasing volatiles and remobilizing metals. Dehydration around the Crossecho Stock may have released fluids which leached, transported, and deposited metals in favorable sites. Cooling fractures in the quartz-feldspar porphy-. ries, intruded early from the Crossecho Stock magma cham ber, may have acted as favorable sites for mineralization.

Such intrusions and the increased thermal gradient are the driving forces behind metamorphic secretion. The general metamorphic secretion theory implies that gold and other constituents in epigenetic gold deposits are derived during metamorphic events from the enclosing host rock or from above, below, or adjacent to the deposit. This theory is in opposition to the theory of magmatic origin of mineralizing fluids due to differentiation. The magmatic origin was reviewed by Gallagher (1940), and strongly supported by Spurr (1923) in his books on this theory, but has recently been subject to much controversy (Boyle, 1979, p.392-394). Marmont (1983) concluded that no auriferous felsic intrusion could be considered solely responsible for the associated mineralization.

Several authors have proposed that mafic volcanics, mafic i~trusives, and associated iron-rich sediments are 169

the ultimate source of gold in epigenetic gold deposits.

Boyle (1959) mad.e this conclusion for the Yellowknife area and Viljoen and others (1969) for the Barberton Greenstone

Belt, South Africa. Tilling and others (1973) noted the higher gold content in greenstones but questioned that they. were more favorable sources for gold. Mackasey and others

(1974) concluded that felsic intrusions in volcanic terraines were not the source of gold but acted as con centrating agents supplying heat, volatiles, and silica which in turn extracted gold from the surrounding mafic volcanics. The Crossecho Stock may have had a similiar role at the Goldlund deposit.

It appears that the gold concentrations in the albitized tonalite dikes resulted from mobilization and migration of gold from the surrounding volcanics and sediments into the fracture system rather than from a high primary concentration of gold in the tonalites. High gold values have not only been found in the tonalite dikes but also in a quartz-feldspar porphyry dike in old zone #4

(Frohberg, 1952), and occasionally in the volcanics.

Although the primary gold concentration of the original tonalites may have been high, the amount now present suggests the addition of gold from other sources, most notably the surrounding volcanics. The albitized tonalite dikes at Goldlund are surrounded by acidic to basic

Keewatin. volcanics and associated sediments and pyro clastics. The exact mechanisms involved in the secretion 170

and deposition of gold such as mobilization, migration, and

concentration are not clearly understood (Boyle, 1979).

When the volcanics and sediments of the Goldlund Mine

area were subjected to regional metamorphic conditions,

volatiles, water, silica, and metals were most likely

mobilized from the volcanic pile. The solutions would then

migrate by mass transport through shear zones, faults, and

fractures or by diffusion to structurally and chemically

favorable sites. Boyle (1979) concluded that due to the

deep-seated conditions under which most Precambrian l deposits form, diffusion is most likely the main process of migration, and he describes in detail the various mechan

isms of diffusion in epigenetic gold deposits.

Metasomatic Exchange with the Tonalite Dikes

The structurally and chemically favorable sites of the

Goldlund deposit are the dilatant zones or tension

fractures in the albitized tonalite dikes. The fractures

acted as conduits allowing the introduction of CO2 , S, and metal-rich fluids and subsequent rnetasomatic alteration of

the tonalite and vein formation as fracture fillings. The

metasomatic exchanges and alteration types are discussed in

detail in Chapter 4, section 3.

Changing Fluid Composition and Mineralogy

The precipitation of specific constituents with fall

ing temperatures led to the change of the mineralizing

fluid composition and subsequent changes in mineralogy. 171

Changes in the gangue mineral sequence included the for mation of calcite after ankerite late in the paragenetic sequence. At Goldlund, an early, high-temperature stage of mineralization formed pyrite, xenotime, scheelite, mag netite, and ilmenite. This was followed by a dominantly sulfide stage with the formation of pyrite, sphalerite, chalcopyrite, and galena. The tellurides and gold formed late in the paragenetic sequence due to the presence of tellurium and gold and at lower temperatures. CHAPTER 5

CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE STUDY

5.1 CONCLUSIONS

1. Complex petrologic processes formed the Goldlund gold deposit. The Archean rocks record a complex geologic history of the area which includes: early volcanic activity, resulting in a thick volcanic pile; syn-volcanic intrusion and extrusion; the onset of the Kenoran Orogeny; related regional deformation, metamorphism, and intrusion into the supracrustal assemblages; and finally, veining, alteration, and associated gold mineralization.

2. The Goldlund gold deposit was formed in distinct stages. These stages include: widespread volcanic activ ity and intrusion of the tonalite dikes; regional meta morphism and deformation, which increased the thermal gradient of the area and formed tension fractures in the tonalite dikes; intrusion of the Crossecho Stock and associated rock types; liberation of gold from the surrounding volcanics (metamorphic secretion); migration of fluids to the tension fractures; metasomatic exchange between the fluids and the tonalite dikes and subsequent alteration; and gold deposition by crystallization.

3. The albitized tonalite dikes are not related to the

Crossecho Stock and other intrusive rock types in the area, as had been suggested by other authors. The albitized 173 tonalite dikes appear to be syn-volcanic in origin and probably were derived by partial melting of amphibolite and intruded earlier than the Crossecho Stock and other related rocks.

4. The Crossecho Stock, quartz-feldspar porphyry dikes, and the quartz monzonite stock are all genetically related.

The quartz-feldspar porphyries and the quartz monzonite stock were probably differentiated fractions that were tapped from the top of the Crossecho Stock magma chamber by fracturing and formed the dikes and an offshoot intrusion, the stock. The Crossecho Stock represents a later pulse of magma which formed the core of the intrusion. The above rock types are interpreted to have been intruded into the supracrustal assemblages during active plutonism of the

Kenoran Orogeny.

5. The host rocks of the gold mineralization are albitized tonalite dikes. Two phases of albitized tonalite exist. A dark, fine-grained, border phase, and a light, fine- to medium-grained phase in which the majority of gold mineral ization occurs. The veins in the albitized tonalite dikes are fracture fillings. Gold occurs in quartz veins and associated alteration haloes within the dikes.

6. Two alteration zones were recognized in the albitized tonalites: a zone of visible alteration near the vein and a zone af cryptic alteration farther from the vein. Carbon dioxide; Na, Ca, s, and Mn migrated into the tonalites

',, ,,.,. ., 174

from the veins, and Fe, H20, Mg, and K were added to the veins from the tonalites. Five alteration types were also recognized. They include: carbonatization, albitization, pyritization, desilicification, and dehydration. Chlorite, biotite and the albite/quartz intergrowths were broken down in the process of alteration. Liberated iron and magnesium combined with the introduced carbon dioxide, calcium, and sulfur to form secondary carbonate (carbonatization) and pyrite (pyritization). Liberated silica migrated to the veins and formed quartz (desilicification) and also combined with introduced sodium to form secondary albite

(albitization).

7. The paragenetic sequence of the Goldlund Mine minerals consisted of an early, high temperature oxide, pyrite, scheelite, and xenotime stage, followed by a dominantly sulfide stage, and concluded with a late, low temperature gold and telluride stage which deposited gold, petzite, calaverite, and altaite. The different stages occurred as a result of falling temperatures and changes in the composition of the ore-bearing fluids.

5.2 RECOMMENDATIONS FOR FUTURE STUDY Other studies could be conducted that would help in understanding further the processes and mechanisms respon sible for the formation of the Goldlund Deposit and other similia~ deposits. Some suggestions include: 175

l. More detailed mapping of the mine and surrounding area

is needed to better document the structures and geologic

relationships.

2. Chemical and petrographic examination of the grano diorite dikes to the northeast could be done to determine whether they are related to the albitized tonalite dikes of the Goldlund area.

3. Detailed chemical examination of the volcanics could be conducted to help prove or disprove that the tonalite dikes were formed by partial melting of metamorphosed volcanics.

Also, gold assays of the volcanic rock types could be used to further speculate on the original source of the gold.

4. Carbon.and oxygen isotopes could be used to speculate on the origin of the ore-bearing fluid at Goldlund. This, along with fluid inclusion studies, would help characterize the ore-bearing fluid and establish a temperature of formation for the deposit.

5. More detailed chemical and petrographic studies of changes occurring at and near the vein/wall rock interface at Goldlund and other deposits would further explain the processes and mechanisms involved in gold deposition and metasomatism and their relationships. APPENDICES APPENDIX A

SAMPLE LOCATIONS 178

TABLE 24

LIST OF UNDERGROUND SAMPLE LOCATIONS

Based on grid system from Goldlund Mines Limited No.l zone (200 foot) plan 1st level- west (W) and east (E).

From unpublished mine maps. Scale 1n; 20'. May, 1983 IW), July, 1984 IE).

SAMPLE COORDINATES SAMPLE COORDINATES

UG-1 14286N, 15621E UG-17 13644N, 14306E

UG-2 14297N, 15681E UG-18 13581N, 14189E

UG-3 13215N, 13398E UG-19 13495N, 14030E

UG-4 13214N, 13398E UG-20 13439N, 13948E

UG-5 13119N, 12902E UG-21 13373N, 13781E

UG-6 13166N, 13173E UG-22 13275N, 13619E

UG-7 13 7_87N, 14508E UG-23A 13276N, 13546E

UG-8 13 789N, 14516E UG-23B 13260N, 13548E

UG-9 14139N, 15137E UG-24 13237N, 13473E

UG-10 14067N, 15083E UG-25 13225N, 13340E

UG-11 14013N, 14954E UG-26 13165N, l3250E

UG-12 13936N, 14813E UG-27 13146N, 13163E

UG-13 13907N, 14735E UG-28 13144N, 13128E

UG-14 13843N, 14640E UG-29 13139N, 13065E

UG-15 13828N, 14596E UG-30A 13120N, 12938E

UG-16 13765N, 14491E UG-31 13126N, 13057E

No current maps were available to place samples UG-30B and UG-32 on the same map grid system.

- Sample UG-30B was taken from the hanging wall at survey marker l-25W. - Sample UG-32 was taken from the hanging wall at survey marker 1-34W. 179

Figure 48: S.ample locations, eastern study area. •- Individual Sample Locations. I See Figure 4 for detailed geology. I l

1. l

\ i I I I ., .),: z \ z ..,. 0 ' 0 ..... 0 w 0 \ 0 ... \ '" .... Q ... 0 < \ 0 ....~-·· ,s... 0 ' ... \ .. •• 0- .. .. 0 - - ' \ - w ' ' 300001: a: u \ .. 0- \ w- Ir...... \ I ...... ,, ::,; I ""o:. \ z r.o ' !• a: \ -< ''\ :,; s. ' \ ... 'l!a ?() \ ou "' ' ... a:\ •· zo I ...- \ < a: ·< ' :! a. 0"' ·'!'.. • u a.- 'fo'\ \ '\ J I 'O \ < 1'-.a: •• ~ -...... ___ 11'""" ' ' :i ·~,- • ~ ' I \ \ \ lI \ ' :IOOOIH \ I \ :,;\ " \ 1 \ / . di '''\,f.,. \ I ~ \di .. "'s. '•. \ 0 "> \ :..,\ 0 \ ' ' \ ,, \" ,ooot-i .. ""s. ..a..- 0 .,,-,> •..• \ \ ,,_..... ;- \\ .;O -,>+ C,, \ ... \ \ '\ \ \ ...... I• "' \ \ .. >, ci . -.r:.. _ C: (; 0 I =o l .. I oa. \ \ .. I I "0 \ \ ci ::! \ \ \ --z N \ \ 0 -- l"' \ I f .. . 0 0 liJ ' ~ 181

Figure 49: Sample locations, western study area. e.- Individual Sample Locations. •rtttr t ltai#nbw ++ -· - - '" '(t1il'flll

/' ., ...... ""1-" "'(, ( .... , ; ,-""''- "' 'fl'o •" ," . , _ _.. .,., I , o'.. "'"" t ,-- /\ I I ~ w,,,,,- I ( t,.'t-'E;. , _..,,,,. I "' (;,,q."' (;, ~ , I I 1 ,'fl'"' ~., f l ~o" I I N I I 0 ':, ':,'E;. C I \ I \ c~ I \ I ' 1 CROSSECHO \ I ' (GRANITIC STOCK \ t CLS-10 ,/ ,r"' LS-9 I CLS-8 ~-... ,"

... i,.!il C...... i,.f>' ~Quarlz-Feldsper y.O ~ Porphyry Dike ~~ .. 0 0.2 0,4 0,8 0.8 1KM ~o'"' ,v-~~""' CLS-2 ,I, CLS-1 2

183

Figure 50: Sample locations, east extension (closeup).

•- Individual Sample Locations.

A- Survey Marker. ,...;...... ::..--. µ·-··----- .. ------·-·---- -~--~-~-----~~ .....

EA-30•

eEA-14

EA-33e •EA-20 ;;:.. EA-32 •

DARK-PHASE,

I.) 20 40FT ~- o· ~-•• ·s10N 185

Figure 51: Sample locations, ore zone #2 (closeup). Local survey grid based on coordinates of S-1 of 16200N and 16800E and bearing from S-1 to S-4 of N70°E magnitude. Single numbers denote trench number.

•- Individual Sample Location.

A- survey Marker. ,,,, \ ,', .. \ "'0 \ .., \'' -z .. \ .. N \ ' 0 I N .. \

0 • I o,. = ~.. I ..= l 0 1 .. ..I ";_. tP \ ~ .. \ "'11, N 0 \ di \

.. s,..

' ..~ ' 0 ' a.. '"' ..... ~ I Q. ' ' ' ... ' N~ C\I ' ."-'" ~I" · 1= ...... -~ I :, w .. 0 z 0 N w cc I 0 APPENDIX B

METHODS AND PROCEDURE 188

METHODS AND ANALYTICAL PROCEDURES

B.1 SAMPLING

Sampling was done on the surface in ore zone #2, ore zone #3, the east extension, and surrounding areas. Under ground sampling was conducted in ore zone #1 and in other locations along the main drift of the 200 foot level.

Additional sampling was done on the Crossecho Stock as well as other intrusives of the area. The freshest samples possible were collected for both petrographic and geo chemical studies with the average sample size approximately

12Kg.

Samples collected for alteration studies were of two types. The first type included non-veined and visibly un altered samples from both the surface and underground of the light-phase, albitized tonalite host rock. The samples were used for comparison with the visibly altered host rock samples. A total of 9 samples were used for this purpose.

The second type were samples that displayed gradation from visibly unaltered rock (zone of cryptic alteration), to visible alteration haloes surrounding quartz veins.

Four large samples were collected of this type. The first sample was from stope 1-05CW and was cut into 9 different sections. The sample contained 0.25cm and 2.7cm quartz veins with 4.0cm and 7.0cm alteration haloes respectively.

The second sample was from stope 1-13E and was cut into 6 sections on one side of the vein. The sample contained a 189

3.3cm alteration halo and approximately 7.5cm of cryptic

ally altered material. The third and fourth samples were

from the open pit. Sample OP-A-J was cut into 10 sections

and contained a 4.0cm quartz vein, a 4.5cm alteration halo,

and approximately 17.5cm of cryptically altered material on

the one side of the vein. Sample OP-3A-3J was cut into 10 1 sections with gradations studied on both sides of a 4.5cm I vein. The sample contained alteration haloes of 1.7cm and 1.8cm as well as 5.5cm and 2.5cm cryptically altered rock

respectively.

B.2 ELECTRON PROBE MICROANALYSIS

Analysis of various minerals was performed on polished

thin sections using a JEOL 35C Scanning electron micro

scope/ electron probe microanalyzer (SEM/EPMA), utilizing a

KEVEX energy dispersive solid state detector. The system

was operated at an accelerating voltage of 15 Kev and a

beam current of 920 pa. All of the analyses were performed

with a 200 second counting time. The X-ray spectra was

fitted using the Tracor Northern XML Program which utilizes

natural and synthetic standards from the Natural Materials

Analytical Laboratory at the University of North Dakota.

Matrix correction was done using the ZAF correction program

of Tracor Northern. Precision and accuracy of 14 natural and synthetic standards are listed in Table 25. Six

analyses per standard were averaged and compared to published compositions f"or the standards. Relative error and standard deviation (1) was calculated for each. Some • 1!: 1, t ~l,1 81 I ~ ~ •. 1, 0 0 8'.0 •• i .... j " ' ' C11 t I O I J f*;; ....

8'' 8'' 0 •• •• ~0 ••'· '· ~0 ••~ '· 01' •'

iE S, I ~!'-1 'iE~ -,.i. art """a* :::o, i i ll 191 heterogeneity in the standards and occasional inclusions may account for observed errors. Minor differences at low concentrations account for the large relative errors.

Synthetic calaverite and krennerite, natural chalcopyrite, and Au, Ag, Te, Pb, cu, Co, Zn, Ni, and Fe metal standards were used for microprobe studies of the ore minerals.

The procedure for determining the number of ions for individual minerals varied. Feldspars were normalized assuming 5 total cations with Si, Al, Ca, Na, K, and ferric iron the only cations used in the calculations. Ilmenite was normalized based on 2 total cations and assuming 3 oxygens. Magnetite was normalized based on 3 total cations and assuming 4 oxygens. Both ferrous and ferric iron were calculated for both magnetite and ilmenite. Apatite was normalized based on 8 total cations and assuming 1 OH.

Sphene was normalized based on 3 total cations and assuming all iron was ferrous. Epidote was normalized based on 8 total cations, 1 OH, and assuming that all iron was ferric.

Hornblende, chlorite, and biotite were normalized based on

(Oz2(0Hl2l, i01o(OHla), and (01o(OHJ2l respectively, and assuming all iron was ferrous. Matrix and bulk composi tions were reported as atom percent with oxygen calculated by difference and iron reported as Fe2+.

B.3 ·x-RAY FLUORESCENCE ANALYSIS

Samples used in X-ray fluorescence analysis were first broken with a sledge into fist-size pieces totalling approximately 1Kg. A hydraulic rock splitter was then used 192

to break the samples into pieces less than 6.0cm in length.

Weathered material was separated from the unweathered material with a total of approximately 300-400 grams of unweathered sample remaining.

The samples were then crushed in a jaw crusher with a case-hardened steel impact plate and a jaw opening size of

1.0cm. The weathered material was passed through the crusher first and discarded before the unweathered portion was run through, A second crushing step, with a 4.0mm jaw opening size, was then performed. Between samples the jaw crusher assemblage was washed and scrubbed with water and dried using laboratory air.

The sample was next split from the 300-400 grams down to 32 grams using a splitter with 2.5cm openings. The splitter was blown clean with laboratory air in between samples.

The 32 gram samples were then ground in a Spex

Mixer/Mill for approximately 6 minutes using a large tungsten carbide vial and two tungsten carbide balls. The samples were then split down to 12 and 20 grams respective ly. The 12 gram samples were divided and ground for approximately 6 minutes in 4 leucite cylinders with tungsten carbide caps and 1 tungsten carbide ball per cylinder. Between samples, the apparatus for both grinding steps was scrubbed and washed using distilled water and blown dry using laboratory air. The 12 gram samples were ground Iurther using an agate morter and pestal. Final 193

grain size was generally less than 60 microns.

Five to 6.5 gram splits of sample were then pressed

for 3 minutes with a binder of 3 drops of distilled water

in a 30 ton press at 5 tons. The pressed pellets were then

ready for major and trace element XRF analysis.

ALTERATION PROFILES- Samples used for alteration studies

required additional preparation steps before the above

steps could.be completed. The large alteration samples

were first cut into smaller samples with the cuts made

parallel to the vein present in the large sample. The

cuts were made to sample the visibly altered rock and the

visibly unaltered rock (zone of cryptic alteration). The

sample width depended on the width of the alteration halo,

with the cuts spaced more closely for the narrower haloes.

The cut samples were then ground on a lap wheel, using

silicon carbide powder to eliminate any contamination from

the saw blade, and then washed. This prepared samples for

the procedure mentioned above.

Major and trace element chemical analyses were per

formed on a fully automated Rigaku $/Max- E/S wavelength

dispersive X-ray fluorescence spectrometer. The Criss

fundamental alphas method was used for calculating major

element chemical analyses (Criss Software, Inc.), and trace I elements were calculated using regression analysis and intensity correction algprithms. seven acidic to inter

mediate whole-rock standards were used for major element 194

calibration and 26 for trace element calibration. Total

iron content (Fez03T) was converted to FeO and Fe2o3 using the following formulas:

%Fe203 = %Fe203T * Y %Fe0 = (%Fe203T - %Fe203) * 0.8998 where: Y = 0.13 for the monzodiorite samples and samples UG-19 and Z3-5;

Y = 0.40 for all other rock type samples.

The value of Y was estimated from ferrous and ferric

iron values supplied for specific samples, run as dup

licates, by the Ontario Geological Survey Geoscience

Laboratories.

The major element precision is shown by the results l obtained from ten test runs.on seven whole-rock standards

over a period of one week. This information is given in I Table 26. Accuracy of the analyses was estimated by analyzing the seven whole-rock standards and comparing the

estimated weight percentage and the recommended weight

percentage. Table 27 lists the major element accuracies as

the 95% confidence limit around the estimated weight

percent.

B.4 MODAL ANALYSIS Modal analysis was performed on polished thin sections

of both the light- and dark-phase, albitized tonalites.

Because of the complex ~ature of the intergrowths, the

difficulty in optically determining the mineralogy of the 19 5

TABLE 26

MAJOR ELEMENT PRECISION (Data from 10 test runs*)

Standard G-2 QL0-1 GR GS-N FK-N SDC-1 RGM-1

Si02 69.087 67.298 74.183 67.187 65.028 67.124 71.920 1. 084 0.377 0.450 0.283 0.242 0.176 0.813

A1 203 15.257 16.247 12.450 15.015 18.556 15.929 13.312 0.245 0.175 0.185 0.193 0.243 0.146 0.201

Fe2o 3 2.595 4.506 1.383 3.746 0.092 6.780 1.924 0.013 0.023 0.006 0.018 0.002 0.022 0.009

MgO 0.756 0.709 0.027 2.259 0.006 1.668 0.260 0.019 0.034 0.005 0.036 0.001 0.042 0.017

Cao 1.862 3.162 o.724 2.449 0.110 1.411 L112 0.005 0.040 0.003 0.006 0. 001 0.004 0.005

Na2o 4.031 4.434 3.793 3.883 2.543 2.107 3.950 0.046 0.062 0.038 0.046 0.040 0.028 0.052

K2o 4.552 3.618 4.839 4.671 12.808 3.280 4.209 0.043 0.008 0.013 0.009 0.017 0.006 0.019

Tio2 0.479 0.649 0.082 0.665 o. 011 1.021 0.271 0.008 0.006 0.004 0.009 0.010 0.011 0.004

P205 0.144 0. 249 0.000 0.288 0.000 0 .186 0.002 0.009 0.015 0.000 0.008 0 .000 0.008 0.003

MnO 0.033 0.107 0.051 0.057 0.000 0.119 0.039 0.002 0.003 0.002 0.002 0.000 0.001 0 .001

* Opper number is amount present, in weight%. Lower number is standard deviation as% absolute. 196

TABLE 27

MAJOR ELEMENT ACCURACIES

95% Confidence Limits (in weight percent absolute)

OXIDE OXIDE

SiOz +-3.00 Na20 +-0.30 Al203 +-1.05 KzO +-0.25 Fez03 +-0.15 Ti02 +-0.04 MgO +-0.20 MnO +-0.02 cao +-0.15 P205 +-0.07

fine-grained mosaics, and the fine-grain size of most samples, the analyses were based on 500 ccunts using the

SEM/EPMA. Grid spacings were set at approximately one half the average grain size of the sample, and the results are presented in volume percent. The accuracy of the analyses is based on the modal percentages (Van der Plas and Tobi,

1965). For a modal percentage of 28-80%, the accuracy is

+-4%; for 13-28%, +-3%; for 5-13%, +-2%; and for 1-5%, +-

1%.

B.5 SPECIFIC GRAVITY

Specific gravities were measured using a 25.0ml glass pycnometer. The pycnometer was weighed empty and then was filled with distilled water and weighed again to determine the weight of a specific volume of distilled water. The pycnometer was then dried using laboratory air. Approx- . imately 1.4.0 grams of sample ranging in size from 0.1mm up to 10.0mm were placed in the pycnometer and weighed. 197

Distilled water was added until the pycnometer was filled.

Any air that was trapped was liberated by stirring during

filling. The filled pycnometer was then weighed. Specific

gravities were calculated using the formula below.

SPECIFIC GRAVITY= A/{B-C-D+E) Where: A= Sample weight. B= Weight of pycnometer filled with distilled water. C= Weight of pycnometer. D= Weight of pycnometer with sample and filled with distilled water, E= Weight of pycnometer and sample. i The volume of the pycnometer was accurate to +-0.02 ml.

The temperature of the distilled water was held constant to I avoid possible temperature effects on volume. The 9 visibly unaitered light-phase, albitized tonalite samples

and the vein profile samples were used for specific I gravity calculations. I B.6 CIPW NORMATIVE CALCULATIONS

CIPW normative mineralogy was calculated from

chemistries of the various rock types using a program

written by Dr. Robert Stevenson, Natural Materials Analyti

cal Laboratory, University of Nc,rth Dakota. The program

was written using the original work of Cross and others

(1902) and the work of Kelsey (1965) (Stevecson, 1986, oral I communication). l 198

B.7 H20 AND CO2 DETERMINATIONS

H20 and CO2 determinations were performed at the Ontario Geological Survey Geoscience Laboratories. Two

samples (OA-1 and Z2-9) were run as duplicates with a I reproducibility of 0.01% and 0.09% for the CO2 and 0.04% l and 0.07% for total HzO respectively.

l I l

I j i' I APPENDIX C

WHOLE ROCK CHEMICAL ANALYSES OF · SAMPLES USED IN ALTERATION STUDIES

199 200

1• ' I j

APPENDIX C

WHOLE ROCK CHEMICAL ANALYSES OF SAMPLES USED IN ALTERATION STUDIES

The whole-rock chemical analyses that were used in the alteration studies are given in Table 28. The major oxides are given in weight percent values; the minor and trace elements are given in parts per million {ppm). Total iron is given as Fe203. The visibly unaltered average composition used in the composition-volume calculations was calculated from 9 samples: UG-10, UG-12, UG-14, UG-17, UG-22, UG-24, UG-26, UG-29, and EA-14. The chemical analyses for the individual samples are listed in Table 11.

Abbreviations used in this appendix are:

S.G.-----Specific Gravity ND------No data available

VISIBLY UNALTERED AVERAGE (Weight Percent)

Si02 66.81 Ti02 0.76 Al203 12.23 P205 0.23 Fe203 6.73 MnO 0.05 MgO 1.57 H20T 0.62 Cao 2.63 COz 1. 77 Na20 6.05 S.G. 2.770 l K20 0.11

Il 201

I TABLE 28

WHOLE ROCK CHEMICAL ANALYSES OF SAMPLES OSED IN ALTERATION STUDIES Il l SAMPLE 1-05A 1-05B 1-0SC 1-0SD 1-05E 1-05F 1-05G I i I Si02 63.64 63.37 62.95 64.28 64.91 65.13 64.19 11.74 12.22 11.51 11.04 '' Al203 11.19 11.60 11.58 I Fe20:. 5.65 4.83 5.26 6.35 6.06 C 6. 6 5 6.31 ' MgO 1.14 1. 23 1.41 1.54 1. 6 3 2.01 1.76 cao 3.63 3.39 4.06 4.46 2.74 2.90 4.04 NazO 6.33 7.08 6.87 6.55 6.85 6.45 6.64 KzO 0.27 0.07 0.12 0.51 0.50 0.60 0.12 Ti02 0.79 0.75 0.78 0.80 0.85 0.90 0.85 P205 0.24 0.24 0.24 0.25 0.26 0.26 0.15 MnO 0.07 0.08 0.09 0.07 0.06 0.05 0.08 H20T 0.13 0.00 o.oo 0.00 0.13 0.00 0.00 CO2 2.90 3.48 3.83 3.61 2.79 3.18 4.46 Total 95.98 96.12 97.19 100.16 99.00 99.64 99.64

2.783 2.795 2.805 2.765 2.828 2.789 2.681 l S.G. I { Cr 12.7 9.7 6.2 5.2 7.1 11.4 10.8 j Co 31.7 28.8 28.0 34.9 36.6 39.9 35.8 Ni 10.4 11.1 7.7 6.3 10.8 11.0 10.7 Cu 8.4 14.1 15.5 7.9 8.0 7.7 8.0 I Zn 32.5 21.9 25.0 42.1 4 7. 7 61.5 31. 7 l Rb 11.2 5.1 6.5 21. 7 18.1 21.7 4.5 Sr 164.8 269.5 276.2 253.1 279.2 254.5 323.0 y 241.8 234.7 196.9 175.1 225.7 146.0 250.5 Zr 550.8 512.8 481.l 480.9 569.9 619.2 628.2 Nb 25.7 20.8 21.7 22.7 25.1 22.5 24.3 Ba 48.2 o.o o.o 133.3 102.3 143.3 0.0 Pb 15.3 18.6 19.3 14.4 15.6 10. 2 15.6 As 57.6 46.8 55.8 52.7 52.2 55.0 55.3 s 305.7 12315 11294 240.4 108.8 o.o 54.8

Sample key: l-05A (cryptic alteration); 1-05B (visible alteration); 1 1-05C (visible alteration) ; I 1-0SD (cryptic alteration); 1-05E (cryptic alteration l ; l-05F {cryptic alteration); l 1-05G (visible alteration) • ,/ ! 202

J TABLE 28 (continued) ~ t SAMPLE 1-05H l-05I 1-13A l-13B 1-13C 1-13D 1-13E Si02 62.81 64.81 63.06 64.55 65.42 64.38 61. 24 ! Alz03 11.00 11.50 11.17 11.53 11.66 12.13 13.73 1 Fez03 5.82 4.91 5.75 5.85 5.78 4.13 3.54 ' MgO 1.52 1.14 1.42 1.53 1.50 0.91 0.78 CaO 3.96 2.97 4.18 4 .15 3.95 3.35 2.44 Na2o 6.78 7.01 6.05 6.19 6.47 7.25 8.27 KzO 0.04 0.04 0. 29 0.24 0.26 0.09 0.06 Ti02 0.84 0. 79 0.74 0.76 0.76 0.76 0.77 Pz05 0.19 0.27 0.28 0.30 0.26 0.21 0.20 MnO C.08 0.06 0.08 0.10 0.10 0.07 0.04 HzOT 0.00 0.00 0.41 0.40 0.29 0.00 0.22 I CO2 4.44 3.36 2.78 2.96 3.10 2.95 2.46 Total 97.48 96.86 96.21 98.56 99.55 96.32 93.75 l S.G. 2.718 2.778 2.788 2.765 2.754 2.747 2.738 Cr 11.1 8.7 10.7 6.1 9,5 5.5 3.9 Co 31.4 26.7 30.6 29.5 31. 4 23.8 20.7 ~ Ni 11.8 5.2 12.5 10.2 10.0 13.0 11. 3 Ct: 11.8 23.9 12.4 11.3 12.9 14.6 9.1 l Zn 22.9 18.8 39.9 38.1 39.7 19.8 14.2 I Rb 3.9 3.6 11.5 10.7 12.1 6.3 3.8 Sr 326.4 295.3 131.1 133.6 139.6 210. 6 244.4 y 307.4 123.3 227.1 240.5 254.4 311.0 303.3 Zr 619.6 622.1 504.0 509.8 522.7 561.3 606.3 Nb 22.3 19.2 24.9 25.5 25.5 29.4 28.0 I Ba o.o o.o 2.4 22.5 14.5 0.0 0.0 Pb 13.8 17.8 13.3 15.6 14.1 21.7 29.2 As 52.2 52.9 54.7 51.4 51.4 48.1 39.4 j s 1552.7 7589.9 154.3 138.5 378.3 4792.1 9395.7 Saroi::le key: 1-0SH (visible alteration); 1-05I (visible alteration); 1-13A (cryptic alteration); l-13B (cryptic alteration); I 1-13C (cryptic alteration); 1-13D (visible alteration); i-1 1-13E (visible alteration). I I· \' 203

TABLE 28

I (continued) • I j j SAMPLE 1-13F OP-3A OP-3B OP-3C OP-3D OP-3E OP-3F I ' Si02 62.42 62.21 60.44 61.60 61.73 61.79 61. 79 Al20'3 14.19 11. 25 10.51 10.65 10.67 10.55 10.45 Fe203 2.73 5.69 5.58 5.44 5.06 4.67 6.00 MgO 0.86 1.24 1. 32 1. 30 1.22 1.21 1.45 cao 2.44 5.34 6.00 5.61 5.22 4.42 6.23 Na20 8.65 6.69 6.26 6.13 6.21 6.34 5.62 K20 0.06 0.17 0.30 0.36 0.26 0.13 0.50 Ti02 0.75 0.78 0.78 0.75 0.77 0.74 0.76 P205 0.21 0.32 0.30 0.27 0.26 0.29 0.28 MnO 0.05 0.11 0.12 0.11 0.11 0.10 0.13 H20T 0.14 o.oo 0.17 0.15 o.oo 0.23 0.42 CO2 2.50 4.32 4.25 4.09 3.99 3.70 4.06 Total 95.00 98.12 96.03 96.46 95.50 94.17 97.69

S.G. 2.720 2.818 2.753 2.759 2.773 2.685 2.756

Cr 5.8 8.9 6.6 2.7 4.2 6.2 4.9 Co 15.3 30.2 25. 8 28.2 25.5 25.8 30.8 Ni 14.2 a.a 9.9 11. 7 10.3 10.8 8.3 Cu 10.1 8 . 5 8.9 13.5 25.5 35.2 12.5 Zn 15.1 24.0 26.5 30.6 27. 8 30.2 33.0 Rb 3.9 10.0 13.2 14.4 11.9 6.9 19.5 Sr 277.4 216.9 227.9 229.5 236.4 240.1 187.3 y 307.5 269.1 243.8 220.5 216.7 238.9 216.6 Zr 650.4 522.8 524.1 514.2 525.2 495.1 482.3 Nb 27.5 27.5 25.8 23.3 23.4 26.0 23. 6 Ba o.o 56.5 46.3 56.1 36. 3 27.0 133.2 Pb 24.1 17.6 17.2 14.7 16.6 20.3 17.3 As 47.6 52.3 53.6 55.1 52. 9 47.2 49.7 s 5286.0 122.6 144.0 375.8 1338.0 7280.4 384. 3

Sample key: 1-13F (visible alteration); OP-3A (cryptic alteration); OP-3B (cryptic al teratior.); OP-3C (cryptic alteration): OP-3D (visible alteration); OP-3E (visible alteration); OP-3F (cryptic alteration). 204

TABLE 28 1 .I ( continued) I l j SAMPLE OP-3G OP-3H OP-3I OP-'3J OP-A OP-B OP-C I ' Si02 64.26 61. 79 62.00 62.21 65.00 65.62 65.80 Al203 10. 97 10.65 10.68 11.27 11. 57 11.54 11.49 Fe203 5.90 5.89 4.88 4.44 5.27 5.51 5.18 MgO 1.29 1.46 1. 40 1.35 1. 42 1. 46 1.39 cao 4.98 5.64 4.68 4.01 2.93 3;20 3.30 Na20 !: • 91 5.80 6.17 6.81 5.89 5.82 6.09 K20 0.40 0.43 0.21 0.07 0.05 0.05 0.18 Ti02 0.75 0.76 0.76 0.72 0.71 0.69 0.71 P205 0.27 0.26 0.28 0.28 0.15 0.16 0.15 MnO 0.12 0.13 0.11 0.09 0.03 0.04 0.04 H20T 0.32 0.39 0.28 0.14 ND ND ND 1 CO2 3.39 3.77 3.80 3.81 ND ND ND Total 98.56 96.97 95.25 95.20 93 .02 94.17 94.33 ! S.G. 2.739 2.738 2.769 2.758 2.740 2.717 2.763 I Cr 4.1 4.2 18.5 8.3 4.0 4.6 5.4 Co 31.0 28.9 26.3 26.1 27.0 29.6 2 5. 8 Ni 8.9 11.9 12.6 11.6 15.1 10.9 14 .o l Cu 13.4 20.8 143.2 104.9 7.9 8.3 7.9 I Zn 3 4. 9 35.5 439.7 538.2 46.0 40.2 36.1 Rb 16.5 17.3 10.9 5.0 4.3 5. 1 8.4 Sr 186.9 200.4 215.4 249.9 113.7 113.8 119.5 I• y 224. 3 243.9 252.0 275.0 299.4 284.4 274.9 I Zr 490.0 503.6 510.3 541. 8 679.3 663.6 652.6 Nb 23.9 26.0 24.9 26.4 29.8 30.1 28.8 Ba 97.3 95.7 44.6 11.4 o.o 0.0 0.0 Pb 16.2 15.6 28.8 36.5 18.9 16.1 13.7 As 54.9 54.8 43.8 38.1 51. 0 49.3 5 2. 0 s 487.4 737.5 3826.0 7724.0 53.6 0.0 3 5. 8

Sample key: OP-3G (cryptic alteratior:): OP-3H (visible alteration); OP-3I (visible alteration); OP-3J (visible alteration); l OP-A (cryptic alteration); OP-B (cryptic alteration); I OP-C (cryptic alteration). l ! i 1 205 TABLE 28 lI (continued) I l SAMPLE OP-D OP-E Ol'-F OP-G OP-H I OP-I OP-J I SiOz 65.12 64.92 64.48 61.69 62.07 62.59 62.11 I Alz03 11.46 11.27 10.86 11.08 11. 65 12.17 12.38 Fe2o 3 5.35 5.09 4.74 4.83 4.21 4.41 4.34 MgO 1.43 1.4 7 1.46 1.48 1.41 1.45 1.28 I Cao 3.25 3.87 3.49 3.56 3.44 3.39 3.16 Na20 6.07 6.05 6.36 6.77 7.04 7.36 7.40 l 1<20 0.31 0.66 0.32 0.09 0.07 0.07 0 .09 Ti02 0.70 0.73 0.72 0.69 0.63 0.65 0.64 P205 0.15 0.17 0.16 0.12 0.15 0.15 0.19 MnO 0.05 0.06 0.06 0.06 0.07 0.07 0.06 j H20T ND ND ND ND ND ND ND I CO2 ND ND ND ND ND ND ND Total 93.89 94.29 92.65 90.37 90.74 92.31 91.65

S.G. 2.738 2.749 2.748 2.764 2.762 2.781 2.777

I Cr 4;0 1.6 9.1 13.2 2.0 9.2 2.7 Co 26.2 25.4 21.1 23.4 19.2 23.6 22.1 j Ni 14.2 12.9 14.7 9.7 7.9 8.9 3.9 Cu 8.2 8.4 14.8 21.0 16.4 16.2 51. 3 i Zn 37.8 36.5 31. 8 24.0 18.4 17.8 20. 4 I Rb 14.7 27.4 14.7 5.0 4.2 3.6 5.7 Sr 128.3 176.5 205.9 240.3 235. 4 237.1 232.4 l y 255.1 249.3 257.4 211.1 184.7 160.9 104.3 j Zr 642.5 648.3 681. 4 676.6 637.3 656.8 660.9 Nb 29.2 27.4 28.6 30.8 26.l 21. 5 19.7 I Ba 22.3 99.8 16.6 o.o o.o 0.0 0.0 Pb 12.7 13.2 15.0 21.1 25.5 24.8 24.1 I As 51.0 56.9 56.0 52.7 43.3 45. 8 44. 8 I s 59.7 365.9 1755.7 5292.6 11361 11966 10862 j

I Sample key: OP-D (cryptic alteration); OP-E (cryptic alteration); OP-F (cryptic alteration); OP-G (cryptic alteration); OP-H (visible alteration); OP-I (visible alteration); OP-J (visible alteration) • J I I I I I l I J !

APPENDIX D

CHEMICAL ANALYSES AND CIPW NORMATIVE MINERALOGY OF MISCELLANEOUS ROCK TYPES

206 207 l' I I l I

APPENDIX D

CHEMICAL ANALYSES AND CIPW NORMATIVE MINERALOGY OF MISCELLANEOUS ROCK TYPES I ' I Abbreviations used in this appendix are: QZ-----normative quartz I OR-----norrnative orthoclase AB-----normative albite ; AN-----normative anorthite wo-----normative wollastonite j DI-----normative diopside HY-----norrnative hypersthene i co-----normative ccrundum MT-----normative magnetite I IL-----norrnative ilmenite I AP-----normative apatite i I ! I ' I I i I I I 208

TABLE 29 CHEMICAL ANALYSES AND CIPW NORMATIVE MINERALOGY OF MISCELLANEOUS ROCK TYPES

I SAMPLE I UG-11 UG-28 UG-30B UG-32 OG-18 OG-23A Si02 5-9. 48 57.39 62.24 65 .10 63.51 73.33 I Al203 13.50 16.89 11.89 11. 45 11.41 13.47 l Fe203 4.66 0.92 2.85 2.58 2.90 0.86 i FeO 6.28 5.52 3.85 3.48 3.92 1.17 MgO 3,41 1. 75 2.09 1.54 1. 42 0.50 I Cao 5.01 6.48 4.86 3.12 5.18 2.56 Na2 o 3.69 4.60 5.47 5.61 4.27 2.61 I K20 0.10 1.90 0.09 0.04 0.81 1. 97 J Ti02 1. 34 1.11 1.02 0.78 0.79 0 .13 I P205 0.23 0.28 0.26 0.23 0.23 o.oo MnO 0.15 0.10 0.08 0.06 0.06 0.03 I Total 97.85 96.94 94.70 93.99 94.50 96.63 Cr 10.4 20.9 10.6 2.4 5.6 2.5 J' Co 66.2 28.8 40.7 38.8 40.6 14.6 I Ni 6.1 10.3 11.5 9.4 6.7 0.9 Cu 9.9 8.0 7.7 9.4 7.7 8.9 Zn 49.8 59.0 49.2 4 7. 2 31. 2 20,9 Rb 5.8 32.7 6.7 4.9 20.1 48.5 Sr 110.7 235.9 200.3 74.7 92.1 95 .3 y 98,5 21.1 192.4 262.2 209.0 17.4 Zr 322.8 169.4 516.6 600.9 514.3 162.0 Nb 16.9 11.0 22.4 28.2 23.8 16.8 Ba 9.1 187.8 o.o 0.0 103.5 438.7 Pb 12.1 14.2 12.4 10.8 12.1 14.7 As 57.6 58.1 57.1 53.8 55.2 48.6 I s 247.7 48.5 751.9 o.o 77.6 0.0 I I QZ 21.02 6.61 20.09 25.87 25.95 45.33 l OR 0.60 11. 58 0.56 0. 25 5.06 12.05 AB 31. 91 40.15 48.87 50.50 38.23 22.86 AN 20.42 20.45 8.05 6.32 10.13 13.14 I WO o.oo o.oo 0.00 o.oo 0.00 0.00 DI 2.82 9.13 12.72 7.02 12.81 0.00 HY 13.19 7.86 2.65 3.91 1.21 2.60 co 0.00 0.00 0.00 o.oo 0.00 2.47 MT 6.90 1.37 4.37 3.98 4.46 1.30 IL 2.60 2.17 2.05 1.58 1.59 0.26 AP 0.55 0.67 0.64 0.57 0.57 0.00

Sample key, UG-11- Altered, Light-Phase, alb, tonalite?i UG-28- Monzodiorite1 UG-30B- Brecciated, albitized tonalite1 UG-32- Light-Phase, albitized tonalite; UG-18- Altered, Dark-Phase, alb. tonalite?; OG-23A- Quartz porphyry. , 209 ' ' TABLE 29 (continued)

SAMPLE OA-1 UG-1 UG-3 UG-5 UG-6 OA-10

SiOz 68.97 64.89 65.61 65.10 63.81 62.07 Alz03 11.89 11.48 ,12.10 11.61 12.71 13.16 Fez03 3.49 3.04 3.50 2.58 3.38 2.63 FeO 4.71 4.09 4.71 3.47 4.56 3.55 MgO 1.53 1.47 1.39 1.90 1. 92 1. 44 cao 1.87 5.18 3.85 5.78 5.52 5.30 Na20 5.23 2.01 2.05 2.54 2.02 3.60 K20 0.10 2.10 2.59 0.90 1.63 1.12 TiOz 0.98 0.79 0.95 0.74 0.87 0.78 P205 0.23 0.15 0.27 0.11 0. 24 0.20 MnO 0.06 0.07 0.11 0.08 0.08 0.13 Total 99.66 95.27 97 .13 94.81 96.74 93.98

Cr 3.7 6.3 o.o 3.9 3.7 2.3 Co 56.3 40.2 48.4 31.6 44.6 33.5 Ni 7.1 10.1 7.6 10.2 5.7 8.0 Cu 7.9 7.8 8.4 9.0 21.0 9.9 Zn 44.3 40.2 56.6 335.9 45.9 198.7 Rb 19.2 38.2 78.3 20.6 28.1 23.9 Sr 151.0 65.5 79.3 153.5 86.9 123.6 y 139.6 235.3 163.8 212.9 172.1 206.1 Zr 472.2 590.7 499.9 555.9 450.2 544.3 Nb 22.1 26.7 24.5 25.0 24.3 25.7 Ba 121. 7 143.1 224.9 · 29.1 86.3 130.1 Pb 12.2 11.2 11.0 11. 4 12 .3 10.7 As 52.4 63.1 60.9 53.4 55.0 57.4 s 102.6 o.o 0.0 0.0 o.o o.o

QZ 28.58 34.01 33.41 34.55 31. 98 25.80 OR 4.15 13.02 15.76 5.61 9.96 7.04 AB 44.41 17.85 17.86 22.67 17.67 32.41 AN 6.92 16.90 16.64 18.58 21.50 17.49 WO 0.00 0.00 0.00 o.oo o.oo 0.00 DI 0.73 7.50 1.01 8.90 4.28 7.50 HY 7.73 4.16 7.60 4.00 7.27 3.62 co 0.00 o.oo o.oo o.oo 0.00 0.00 MT 5.07 4.62 5.22 3.94 5.07 4.05 IL 1.87 1.57 1.86 1.48 1.71 1.58 AP 0.54 0.37 0.65 0.27 0.58 0.49

Sample key: OA-1- Dark-Phase, albitized tonalite?; UG-1- Sheared, albitized tonalite, Na poor; UG-3- Sheared, albitized tonalite, Na poor; UG-5- Sheared, albitized tonalite, Na poor; UG-6- Sheared, albitized tonalite, Na poor; OA-10- Quartzite? 210

TABLE 29 (continued)

SAMPLE Z2-2 Z2-6 Z2-11 UG-19 Z3-5

SiOz 54.90 55. 94 64.77 50.52 50.62 Alz03 12.68 10.53 17.23 13.01 14.50 Fe203 4.40 2.97 1. 25 2.08 1. 88 FeO 5.94 4.00 1.68 12.53 11.34 MgO 1. 76 2.75 1.66 2.34 3.69 cao 10.39 7,49 4.20 9.27 8.74 NazO 0.34 4.98 0.62 1.92 4.04 KzO 2.85 0.26 4.61 0.91 0.10 Ti02 0.88 0.99 0.35 1.98 1.53 P205 0.23 0.22 0.09 0.24 0.26 MnO 0.37 0.15 0.05 0.30 0.26 Total 94.74 90.28 96.51 95.10 96.96

Cr 72.8 16.l 7.2 54.2 3.6 Co 47.7 35. 7 11.0 79.0 0.6 Ni 38.2 5.5 2.7 9.6 2.0 I Cu 34.9 24.2 7.9 17.6 23.9 Zn 67.8 54.5 41. 7 80.8 56.6 Rb 45.5 6.7 96.0 18.0 3.0 Sr 177.8 244.5 124.4 81.6 252.5 l y 18.4 98.5 16.0 26.5 28.8 j Zr 106.5 333.6 170.2 107.5 106.0 Nb 7.8 15.2 9.5 9.3 8.0 Ba 531.8 o.o 412.4 191-.6 o.o I Pb 13.7 12.9 14.4 9.8 10.2 j As 58.2 56.2 58.3 67.4 61. 4 I s 363. 7 3349.6 0.0 166.0 39.9 I QZ 21.42 12.56 32.72 9.57 o.o ' OR 17.78 1.70 28.23 5.65 0.61 I AB 3.04 46.67 5.44 17.08 35.26 AN 26.02 6.21 20.98 25.44 21.80 WO 0.00 1.69 0.00 0.00 o.oo I DI 22.47 23.75 0.00 18 .26 17.89 l HY 0.21 o.oo 5.92 16.28 17.51 cc 0.00 0.00 3.94 0.00 0.00 MT 6.73 4.77 1.87 3.17 2.81 IL 1. 76 2.08 0.69 3.95 3.00 AP 0.56 ·o.57 0.22 0.59 0.62

Sample key: Z2-2- Meta sedimentary rock type?; Z2-6- Highly altered, albitized tonalite?; Z2-11- Quartz porphyry; UG-19- Basalt; Z3-5- Amphibole-rich basalt. REFERENCES CITED , 212 i REFERENCES CITED 1'

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