THESE TERMS GOVERN YOUR USE OF THIS DOCUMENT

Your use of this Ontario Geological Survey document (the “Content”) is governed by the

terms set out on this page (“Terms of Use”). By downloading this Content, you (the “User”) have accepted, and have agreed to be bound by, the Terms of Use.

Content: This Content is offered by the Province of Ontario’s Ministry of Northern Development and Mines (MNDM) as a public service, on an “as-is” basis. Recommendations and statements of opinion expressed in the Content are those of the author or authors and are not to be construed as statement of government policy. You are solely responsible for your use of the Content. You should not rely on the Content for legal advice nor as authoritative in your particular circumstances. Users should verify the accuracy and applicability of any Content before acting on it. MNDM does not guarantee, or make any warranty express or implied, that the Content is current, accurate, complete or reliable. MNDM is not responsible for any damage however caused, which results, directly or indirectly, from your use of the Content. MNDM assumes no legal liability or responsibility for the Content whatsoever. Links to Other Web Sites: This Content may contain links, to Web sites that are not operated by MNDM. Linked Web sites may not be available in French. MNDM neither endorses nor assumes any responsibility for the safety, accuracy or availability of linked Web sites or the information contained on them. The linked Web sites, their operation and content are the responsibility of the person or entity for which they were created or maintained (the “Owner”). Both your use of a linked Web site, and your right to use or reproduce information or materials from a linked Web site, are subject to the terms of use governing that particular Web site. Any comments or inquiries regarding a linked Web site must be directed to its Owner. Copyright: Canadian and international intellectual property laws protect the Content. Unless otherwise indicated, copyright is held by the Queen’s Printer for Ontario. It is recommended that reference to the Content be made in the following form:

Giguere, J.F. 1972. Geology of the Granitehill Lake area, districts of Algoma and Thunder Bay; Ontario Department of Mines and Northern Affairs, Geological Report 95, 33p.

Use and Reproduction of Content: The Content may be used and reproduced only in accordance with applicable intellectual property laws. Non-commercial use of unsubstantial excerpts of the Content is permitted provided that appropriate credit is given and Crown copyright is acknowledged. Any substantial reproduction of the Content or any commercial use of all or part of the Content is prohibited without the prior written permission of MNDM. Substantial reproduction includes the reproduction of any illustration or figure, such as, but not limited to graphs, charts and maps. Commercial use includes commercial distribution of the Content, the reproduction of multiple copies of the Content for any purpose whether or not commercial, use of the Content in commercial publications, and the creation of value-added products using the Content. Contact:

FOR FURTHER INFORMATION ON PLEASE CONTACT: BY TELEPHONE: BY E-MAIL:

The Reproduction of Content

MNDM Publication Services

Local: (705) 670-5691 Toll Free: 1-888-415-9845, ext.

5691 (inside Canada, United States)

pubsales.ndm@ontario.ca

The Purchase of MNDM Publications

MNDM Publication Sales

Local: (705) 670-5691 Toll Free: 1-888-415-9845, ext.

5691 (inside Canada, United States)

pubsales.ndm@ontario.ca

Crown Copyright Queen’s Printer Local: (416) 326-2678 Toll Free: 1-800-668-9938

(inside Canada, United States)

copyright@gov.on.ca

ONTARIO DEPARTMENT OF MINES

AND NORTHERN AFFAIRS

Geological Report 95

Geology of the

Granitehill Lake Area Districts of Algoma and Thunder Bay

By

J . F. GIGUERE

1 9 7 2

ONTARIO DEPARTMENT OF MINES

AND NORTHERN AFFAIRS

HONOURABLE LEO BERNIER, Minister D.P . DOUGLASS, Deputy Minister J . E . THOMSON, Director, Geological Branch

Geology of the

Granitehill Lake Area Districts of Algoma and Thunder Bay

By

J. F. Giguere

Geological Report 95

T O R O N T O

1 9 7 2

Publications of the Ontario Department of Mines and Northern Affairs and price list

are obtainable through the Publications Office, Ontario Department of Mines and Northern Affairs

Parliament Buildings, Queen's Park, Toronto, Ontario and

The Ontario Government Bookstore 880 Bay Street, Toronto, Ontario.

Orders for publications should be accompanied by cheque, or money order, payable to Treasurer of Ontario.

Parts of this publication may be quoted if credit is given to the Ontario Department of Mines and Northern Affairs. It is recommended that reference to this report be made in the following form:

Giguere, J.F. 1972: Geology of the Granitehill Lake Area, Districts of Algoma and Thunder Bay;

Ontario Dept. Mines and Northern Affairs, GR95, 33p. Accompanied by Map 2219, scale 1 inch to 1 mile.

ii 1000—646—1970cc

C O N T E N T S

PAGE

Abstract v

Introduction 1 Field Mapping 2 Acknowledgments 2 Topography 2 Natural Resources 3 Mineral Exploration 3

General Geology 4 Table of Lithologic Units 5

Archean ° Metavolcanics °

Amygdaloidal Lava ° Amphibolite 7 Quartz-Plagioclase(-Chlorite )-Hornblende Schist 7

Metasediments ° Biotite Quartzite £ Quartz-Feldspar Gneiss -9 Biotite (-Hornblende)-Quartz-Feldspar Gneiss 10 Biotite-Quartz-Feldspar Gneiss 10 Garnet (-Biotite)-Hornblende-Feldspar-Quartz Schist 10 Iron Formation 11 Garnet-Amphibole (-Chlorite) -Biotite-Feldspar Schist 11

Mafic and Ultramafic Intrusive Rocks 12 Anorthositic Gneiss 12

Felsic Intrusive and Metamorphic Rocks 12 Migmatites 12

Metasedimentary Migmatites 12 Metavolcanic Migmatites 13

Hybrid Gneiss 14 Hornblende-Biotite-Quartz-Feldspar Gneiss 14

Gneissic Rocks 14 Biotite Granodiorite Gneiss 14 Undifferentiated Migmatites 16

Granitic Rocks 16 Granite 1° Granodiorite and Quartz Monzonite 16 Pegmatite 17 Aplite 17 Magnetite-Rich Granite 17

Proterozoic 1^ Late Mafic Intrusive Rocks 1°

Cenozoic 1 | Pleistocene 1°

Structural Geology 20 Faults 21

Economic Geology 21 Recommendations to Prospectors * 23 Descriptions of Properties and Occurrences 23

Conwest Exploration Company [1954] (1) 23 Delmico Mines Limited [1963] (2) 25 Falconbridge Nickel Mines Limited (3, 4, 5, 6) 25

Moshkinabi Lake Deposit (3) 25 Ice Lake Deposit (4) 27 Foch River Deposit (5) 27 Herbert Township Deposit (6) 27

Gavan Mines Limited [1960] (7) 28 Marlhill Mines Limited [1958] (8) 28 Mining Corporation of Canada (1964) Limited (9, 10, 11, 12) 28

Boot Lake Group [1955] (9) 28 Wowun Lake, Group No. 1 (10) 28 Luckyshoe Lake, Group No. 2 [1958] (11) 29 Group No. 3 [1958] (12) 29

•• i

PAGE New Fortune Mines Limited [1954] (13) 29 Olivier Occurrence (14) 30 Ontario Paper Company Limited, The 30 Selco Exploration Company Limited [1955] (15) 30 Timmins, N.A., Explorations (Ontario) Limited [1954] (16) 30 Trans-Dominion Mining and Oils Corporation [1954] (17) 30

Selected References 31 Index 32

Tables

1-Table of Lithologic Units 4 2-Age Determinations 6 3-Information on File with the Resident Geologists of Thunder Bay and Sault Ste. Marie 24

Figures

1-Key map showing location of the Granitehill Lake area v 2-Pleistocene geology 19 3-Moshkinabi Lake deposit 26

Photographs

1-Minor folding in metasediments 8 2-Hornblende schist inclusion in granodiorite 15

Geological Map (back pocket)

Map 2219 (coloured)—Granitehill Lake area, Algoma and Thunder Bay Districts. Scale, 1 inch to 1 mile.

iv

ABSTRACT

The map-area covers approximately 750 square miles. It is bounded on the north by the Flanders Lake area and the Steven-Kagiano Lake area, on the south by the Black River area and the Dayohessarah Lake area, on the west by the Manitouwadge area, and it extends as far east as Obakamiga Lake. This present report describes the geology, structure, and economic geology of the area.

Figure 1—Key map showing location of the Granitehill Lake area. Scale, 1 inch to 50 miles.

The consolidated rocks are all of Precambrian age, but a large part of the area is blanketed by deposits of glaciofluvial and glaciolacustrine deposits of the Wisconsin glacial epoch.

The oldest rocks of the area have been interpreted to be the sedimentary-volcanic sequences mapped in the central and northern parts of the area. It is assumed that the age of these rocks correlates with the rocks of the Manitouwadge area.

The next youngest are interpreted to be the hybrid migmatites that are metamorphosed sedimentary and volcanic rocks, and are found bordering the granitic areas. Granodiorite occurs in a gneissic and a massive form. The age relationship between these two types is unknown. Granites and pegmatites are found to cut all other rock types, except mafic dikes. The mafic dikes and small circular bodies of gabbro are interpreted to be the youngest rocks of the area, cutting all other types.

Metasediments and metavolcanics near Moshkinabi Lake and traced intermittently through Ice and Foch Lakes are interpreted to be equivalents of similar rocks of the Manitouwadge area, offset to the south by faults.

The presence of sedimentary and volcanic blocks in the granitic rocks and the disjointed nature of the sedimentary-volcanic belt leads the author to conclude that the area is the roof of a batholith and that the Moshkinabi Lake sedimentary and volcanic rocks, as well as the Mani­touwadge fold belt, are roof pendants on the batholith.

Evidence from the map-area and adjoining areas leads the author to believe that the forma­tion of economic sulphide minerals in metasediments coincided with, and was a result of, an alkali vapour phase accompanying the intrusion of late-formed granitic rocks.

Small copper showings in the Ice Lake, Foch Lake, and Moshkinabi Lake areas are presently under study by Falconbridge Nickel Mines Limited, but at the time of this study (1968) no economic quantities had been outlined.

v

Geology

of the

Granitehill Lake Area Districts of Algoma and Thunder Bay

By

J . F. Giguere1

INTRODUCTION

The Granitehill Lake map-area is situated approximately 40 miles north of White River, Ontario. This area straddles the Algoma-Thunder Bay district boundary and falls within the Sault Ste. Marie Mining Division on the east side of the boundary and in the Thunder Bay Mining Division on the west side.

The area covers approximately 750 square miles and is about 24 miles north to south and 32 miles east to west. It is bounded on the north by the Flanders Lake area (Milne 1964) and the Stevens-Kagiano Lake area (Coates 1968), on the south by the Black River area (Milne 1968) and the Dayohessarah Lake area (Fenwick 1967), on the west by the Manitouwadge area (Pye 1967), and it extends as far east as Obakamiga Lake.

It is bounded by Latitudes 49°00'N and 49°20'N and Longitudes 85°05'W and 85°43'W. The lower southeastern corner is accessible by an Abitibi Power and Paper Company Limited road, presently administered and maintained by the On­tario Department of Lands and Forests. The northwestern corner is cut by the Canadian National Railways branch line to Manitouwadge, Ontario.

On the western side of the area, Nickle and Cecil Townships are accessible by The Ontario Paper Company Limited, Camp 70 road from Manitouwadge. The area is partly accessible by one of the main Lake Superior-Hudson Bay canoe routes. The route goes from Lake Superior, by the White River, to White Lake. From there it follows the Shabotik River to the Gum River. At the Gum, it splits into two segments. One segment follows the Granitehill Lake-Obakamiga Lake-Obakamiga River-Nagagami Lake route. The other branch follows the Foch River-Foch Lake-Foch River-Nagagami Lake route. The remainder of the area, that is the northern parts, are reached by pontoon-equipped aircraft from White River, Ontario.

1Geologist, Ontario Department of Mines, Sault Ste. Marie, Ontario. Manuscript accepted for publication by the Chief Geologist, 3 June 1969.

1

Granitehill Lake Area

A C K N O W L E D G M E N T S

The author was ably assisted during the 1967 field season by L. S. Jensen of the Toronto staff, and by the following undergraduate students: R. G. Thompson, E. K. Langtry, and F. d'A. Hung. Mr. Hung also provided assistance during the completion of the field work in May, 1968. L. S. Jensen acted as senior assistant and was responsible for mapping much of the northern part of the area.

The author is indebted to the members of the White River District of the Ontario Department of Lands and Forests for their co-operation, also to the staff of White River Air Services Limited for their many services during the field season.

The author also wishes to thank the exploration staff of Falconbridge Nickel Mines Limited, especially Mr. W. D. Harrison, for co-operation with this project.

T O P O G R A P H Y

The area is cut from the northwest to the southeast by a height of land. This height of land passes west of Osawin River in the northwestern corner of the area, then south of Poppy Lake, touches the northeastern corner of Herbert Township, and passes west of the Foch River system through Roberta and Spooner Townships. It then takes a loop north, passing north of the Gum River, then turns south and passes south of Granitehill Lake. It follows the trend of Granitehill Lake, passing north of Tocheri Creek, then turns southeast through the southeastern corner of the map-area.

Near the height of land drainage tends to be poor, resulting in large areas of swamp. North of the height of land the water drains into James Bay via the Keno-gami River system. On the southern side drainage is into Lake Superior. In the northeastern part of the area there is a 200- to 300-foot topographic difference in the land, in comparison to a 25- to 50-foot variation near and south of the height of land.

2

F I E L D M A P P I N G

The geological mapping was of a reconnaissance nature. It was done on a scale of 1 inch to 1,320 feet, for publication at 1 inch to 1 mile, using air photographs supplied by the Silviculture Section, Timber Branch, Ontario Department of Lands and Forests, and cronaflex base maps prepared by the Cartography Section, Geological Branch, Ontario Department of Mines. Traverses were made into known areas of outcrop based on detection of these outcrop areas from air photographs. Traverses were planned to cross the strike of the rock formations, except in granite areas where lakeshore geology was complemented by widely spaced traverses inland.

Outcrop locations encountered during traverses were plotted on transparent overlays on the air photographs, to which geological information was added. This information was subsequently transferred to the base map for final reproduction. Because of the scale of the published map, areas of abundant outcrops were generalized from air photographs. Small outcrop areas are indicated on the map as black crosses.

BEDROCK IS EXPOSED IN GRANITE AREAS AWAY FROM THE HEIGHT OF LAND TO THE NORTH­EAST. GROUND MORAINE COVERS MOST OF THE AREA IN THE WEST AND SOUTHWEST, RESULTING IN FEW AND SCATTERED OUTCROPS. LAKES IN THE WESTERN PART ARE COMMONLY SURROUNDED B Y SAND.

N A T U R A L R E S O U R C E S

TREES FOUND IN THE AREA ARE PREDOMINANTLY BLACK AND WHITE SPRUCE, BALSAM,

POPLAR, WHITE BIRCH, AND IN SANDY AREAS, JACK PINE. SCRUB ALDERS GROW ALONG CREEK BANKS.

T H E LUMBERING CONCESSIONS IN THE SOUTHEASTERN PART OF THE AREA ARE OWNED B Y

ABITIBI POWER AND PAPER COMPANY LIMITED, BUT ARE NOT AT PRESENT BEING EXPLOITED.

ACTIVE CUTTING IS TAKING PLACE IN NICKLE AND HERBERT TOWNSHIPS AND AREAS NORTH

OF THESE TOWNSHIPS B Y T H E ONTARIO PAPER COMPANY LIMITED.

TOURISM IS ONE OF THE CHIEF SOURCES OF INCOME TO THE AREA DUE TO THE ABUNDANT

WILDLIFE. SPORTSMEN FROM THE UNITED STATES AND CANADA ARE ENCOUNTERED ON VIRTUALLY

EVERY LAKE THAT IS ACCESSIBLE B Y FLOAT-EQUIPPED AIRCRAFT. NORTHERN P I K E , WALLEYE, TROUT,

AND WHITE FISH ARE THE MAIN FISH CATCHES. MOOSE HUNTING IS POPULAR IN THE FALL.

M I N E R A L E X P L O R A T I O N

SERIOUS EXPLORATION IN THE AREA HAS MAINLY TAKEN PLACE ON THE THUNDER BAY SIDE OF THE MAP-AREA, AND BEGAN FOLLOWING THE DISCOVERY OF THE MANITOUWADGE CAMP. I N 1 9 5 4 , NORANDA MINES LIMITED ( G E C O DIVISION) , TRANS-DOMINION MINING AND OILS CORPORATION, AND N E W FORTUNE MINES LIMITED, CARRIED OUT GEOLOGICAL SURVEYS IN NICKLE TOWNSHIP, (PART OF TRANS-DOMINION GROUND WAS ALSO IN GERTRUDE AND CECIL TOWNSHIPS) AND N . A . T I M M I N S EXPLORATIONS (ONTARIO) LIMITED, GEOLOGICALLY MAPPED THE FOCH LAKE AREA BORDERING FOOTE AND FOCH TOWNSHIPS. GAVAN MINES LIMITED, PROSPECTED SEVERAL TOWNSHIPS BETWEEN 1 9 5 4 AND 1 9 6 0 .

I N 1 9 5 5 , THE FOCH LAKE AREA WAS REMAPPED B Y MARLHILL MINES LIMITED IN A RECONNAISSANCE SURVEY; CONWEST EXPLORATION COMPANY LIMITED BEGAN WORK IN NICKLE TOWNSHIP, AND SELCO EXPLORATION COMPANY LIMITED, DRILLED A PROPERTY NORTH OF NICKLE TOWNSHIP. MARLHILL MINES LIMITED MAPPED AND DRILLED (DRILL HOLES NOT SHOWN ON M A P 2 2 1 9 , BACK POCKET) A PROPERTY IN NICKLE TOWNSHIP IN 1 9 5 8 , AND THE MINING CORPORATION OF CANADA ( 1 9 6 4 ) LIMITED BEGAN WORK THAT LED TO THE LEASING OF A PROPERTY NEAR THE SOUTHERN PART OF THE BOUNDARY OF NICKLE AND GEMMELL TOWNSHIPS.

AT PRESENT ( 1 9 6 8 ) , FALCONBRIDGE NICKEL MINES LIMITED, OWNS A PROSPECT NEAR MOSHKINABI LAKE, AN OCCURRENCE OF PYRITE-CHALCOPYRITE PREVIOUSLY TRENCHED B Y DEL-MICO MINES LIMITED, Vi MILE EAST OF ICE LAKE, AND A NEW CHALCOPYRITE-PYRITE OCCUR­RENCE V* MILE WEST OF THE FOCH RIVER IN THE SAME GROUP OF ROCKS.

VERY LITTLE EXPLORATION IS AT PRESENT IN PROGRESS EXCEPT B Y INDIVIDUAL PROSPECTORS AND B Y FALCONBRIDGE NICKEL MINES LIMITED.

O N THE ALGOMA DISTRICT SIDE OF THE MAP-AREA, FALCONBRIDGE NICKEL MINES LIMITED STAKED MOST OF DREW AND CHOLETTE TOWNSHIPS IN 1 9 6 4 , BUT ALLOWED THESE HOLDINGS TO LAPSE WITHIN 1 YEAR WITH NO ASSESSMENT WORK BEING SUBMITTED.

A SMALL OCCURRENCE OF PYRITE WITH TRACE AMOUNTS OF CHALCOPYRITE, LOCATED IN MATTHEWS TOWNSHIP, WAS SHOWN TO THE AUTHOR DURING THE FIELD SEASON B Y A PROS­PECTOR WORKING THE AREA.

3

Granitehill Lake Area

4

GENERAL GEOLOGY

T H E AREA IS UNDERLAIN PREDOMINANTLY B Y A GRANITE BATHOLITH IN WHICH METAVOLCANIC-METASEDIMENTARY ROCKS FORM ROOF PENDANTS. T H E NORTHERNMOST BOUNDARY OF THE BATHO­LITH IS MARKED B Y A BELT OF METASEDIMENTS, METAVOLCANICS, AND MIGMATITE EXTENDING FROM LESSARD TOWNSHIP IN A WEST-NORTHWESTERLY DIRECTION TO AND BEYOND P O P P Y LAKE.

THROUGHOUT THE GRANITE AREAS ARE BLOCKY INCLUSIONS OF METAVOLCANICS AND META­SEDIMENTS. T H E NUMBER OF THESE INCLUSIONS INCREASES AS WELL-DEFINED METASEDIMENTARY AND METAVOLCANIC BELTS ARE APPROACHED. T H E METAVOLCANIC AND METASEDIMENTARY BELTS THEMSELVES ARE COMMONLY INTRUDED B Y THE GRANITE SEPARATING PARTS OF THE BELTS AS IN THE CASE OF THE MOSHKINABI LAKE-ICE LAKE BELT.

T H E SOUTHERN LIMB OF THE MANITOUWADGE METAVOLCANIC-METASEDIMENTARY BELT ( P Y E 1 9 5 7 ) CAN B E TRACED INTERMITTENTLY ACROSS NICKLE TOWNSHIP, WHERE IT IS MAINLY A SERIES OF LENSES MADE U P PREDOMINANTLY OF METASEDIMENTS WITH, RARELY, SMALL BANDS OF METAVOLCANICS. IT IS THERE APPARENTLY FAULTED SOUTH, WHERE IT REAPPEARS NEAR MOSH­KINABI LAKE, (WHICH BORDERS HERBERT AND ROBERTA TOWNSHIPS) AND CAN B E TRACED THROUGH ICE LAKE AND ON TO FOCH LAKE, WHERE IT PINCHES OUT TO THE EAST.

I N NICKLE TOWNSHIP, TO THE SOUTH OF THE PREVIOUSLY MENTIONED LENSES, THERE ARE lit par lit MIGMATITES OF METASEDIMENTARY AND METAVOLCANIC ORIGIN THAT APPEAR TO B E UNRELATED TO THE MANITOUWADGE-TYPE ROCKS.

T H E NORTHERNMOST PART OF THE MAP-AREA IS CROSSED B Y A BELT OF METASEDIMENTS AND METAVOLCANICS HAVING MINERAL ASSEMBLAGES THAT ARE CHARACTERISTIC OF THE AMPHI-BOLITE METAMORPHIC FACIES. THESE ROCKS ARE DIFFERENT IN APPEARANCE FROM THOSE IN THE MANITOUWADGE BELT, AND ARE A CONTINUATION OF THE ROCK SEQUENCES REPORTED IN THE STEVENS-KAGIANO LAKE AREA (COATES 1 9 6 8 , M A P S 2 1 4 0 AND 2 1 4 1 ) AND IN THE FLANDERS LAKE AREA (MILNE 1 9 6 4 , M A P 2 0 4 7 ) . THESE ROCKS ARE OFFSET B Y NUMEROUS FAULTS. T H E SOUTHERN BOUNDARY APPEARS TO B E CONTROLLED IN PART B Y A THRUST FAULT, WHICH HAS BEEN NAMED ON THE STEVENS MAP SHEET (COATES 1 9 6 8 , M A P 2 1 4 0 ) AND KAGIANO MAP SHEET (COATES 1 9 6 8 , M A P 2 1 4 1 ) AS THE LITTLE NAMA CREEK LINEAMENT. THESE ROCKS ARE NOT APPARENTLY CONNECTED TO THOSE OF THE MANITOUWADGE BELT.

MOST OF THE SOUTHERN SECTION OF THE MAP-AREA IS UNDERLAIN B Y A BATHOLITHIC MASS OF GRANITE AND GRANODIORITE CONTAINING HOST ROCK INCLUSIONS, WHICH INCREASE IN NUMBER AS THE BELT OF METASEDIMENTS ON THE SOUTHERN BOUNDARY OF THE MAP-AREA IS AP­PROACHED. T H E EMPLACEMENT OF THE GRANODIORITE PROBABLY COINCIDED WITH THE METAMORPHISM OF THESE OLDER ROCKS.

METAVOLCANIC ROCKS, WHICH OCCUR IN THE NORTHERN PART OF MATTHEWS TOWNSHIP, ARE AN EXTENSION OF THE SAME ROCKS SHOWN ON THE DAYOHESSARAH LAKE AREA MAP (FENWICK 1 9 6 7 ) ; THESE ROCKS CROSS THE SHABOTIK RIVER.

A N AGE DETERMINATION FROM THE MANITOUWADGE AREA SUGGESTS THAT THE AGE OF THE LAST METAMORPHISM WAS APPROXIMATELY 2 , 4 6 5 ± 1 2 5 MILLION YEARS AGO AND PROBABLY DATES THE PERIOD OF GRANITE INTRUSION (LOWDON 1 9 6 1 , P . 6 0 ) . T H E AGE OF THE DIABASE DIKES ARE THOUGHT TO B E HELIKIAN. THIS WOULD B E TRUE IF THE OLIVINE DIABASE, ON HIGHWAY 1 7 , 5 0 MILES SOUTH OF THE MAP-AREA, RADIOMETRICALLY DATED AT 1 , 1 2 0 MILLION YEARS ( L E E C H et al. 1 9 6 3 , P . 7 3 ) IS IN THE SAME DIKE SWARM. THIS WOULD CORRELATE THE DIKES TO THE KEWEENAWAN ROCKS OF THE LAKE SUPERIOR REGION

Table 1 TABLE OF LITHOLOGIC UNITS FOR THE GRANITEHILL LAKE AREA

CENOZOIC

PLEISTOCENE AND RECENT

Sand, gravel, boulders

Unconformity

P R E C A M B R I A N

PROTEROZOIC

LATE MAFIC INTRUSIVE ROCKS

Diabase, porphyritic diabase, gabbro, pegmatitic biotite gabbro

Intrusive Contact

ARCHEAN

FELSIC INTRUSIVE AND METAMORPHIC ROCKS

GRANITIC ROCKS Granite, magnetite-rich granite, granodiorite, quartz-monzonite, pegmatite,

aplite

GNEISSIC ROCKS Biotite granodiorite gneiss

HYBRID GNEISS Hornblende-biotite-quartz-feldspar gneiss

MIGMATITES

Metavolcanic migmatites, metasedimentary migmatites, undifferentiated mig-matites

Contact Indeterminate

MAFIC AND ULTRAMAFIC INTRUSIVE ROCKS Anorthositic gneiss*

Intrusive Contact

METASEDIMENTS

Iron formation, garnet-amphibole(-chlorite)-biotite-feldspar schist Biotite quartzite, quartz-feldspar gneiss, biotite (-hornblende)-quartz-feldspar

gneiss, biotite-quartz-feldspar gneiss, garnet (-biotite)-hornblende-feldspar-quartz schist

METAVOLCANICS Quartz-plagioclase(-chlorite)-hornblende schist, amphibolite, amygdaloidal lava

*The anorthosite is a member of a suite of rocks that are predominantly mafic to ultramafic and are found in adjoining areas.

5

GRANITEHILL L A K E A R E A

Table 2 AGE DETERMINATIONS IN BIOTITE FROM NEAR GRANITEHILL LAKE AREA (AFTER LEECH et al. 1963, p.73; AND LOWDON 1961 p.60)

Rock type K-Ar Age million years

Location

Olivine diabase 1,120 ± 60 Helikian Age

Highway 17-road cut just south of a small stream SV2 miles north of Catfish Lake 48°12'N, 84°53'W.

Biotite paraschist 2,465 ± 125 Road cut 0.3 miles south of Geco shaft, and 3 miles northwest of Manitouwadge; 49°09' 20"N, 85°47'20"W. Map unit 2d, Map 1957-8, Pye 1957.

A R C H E A N

Metavolcanics

A M Y G D A L O I D A L L A V A

THIS ROCK WAS FIRST NOTED IN THE VOLCANIC BELT TO THE SOUTHEAST OF FOCH LAKE.

H E R E IT OCCURS INTERLAYERED WITH THE HORNBLENDE SCHIST IN A ZONE OVER ]At MILE IN

WIDTH. IT CAN B E TRACED FOR 2 MILES TO THE EAST. IT IS PREDOMINANTLY A QUARTZ-

PLAGIOCLASE-HORNBLENDE SCHIST. THIS IS A MEDIUM-GRAINED, DARK GREEN ROCK WITH ROUND

AMYGDULES OF QUARTZ AND PHENOCRYSTS OF PLAGIOCLASE.

T H E ROCK IS COMPOSED MAINLY OF HORNBLENDE REPLACED IN PART B Y CHLORITE. THIS

CHLORITE REPLACEMENT IS RESTRICTED TO A ZONE APPROACHING THE CONTACT WITH THE META-

SEDIMENTS. T H E CONTACT IS COVERED B Y OVERBURDEN. SECONDARY QUARTZ VEINLETS CUT THE

ROCK AND MAY B E SYNGENETIC WITH THE CHLORITE AS THESE QUARTZ VEINLETS ARE LESS COM­

MON AWAY FROM THE CONTACT AREA AND WERE NOT OBSERVED J4 MILE TO THE NORTH OF THE

CONTACT AREA.

T H E HORNBLENDE AND CHLORITE ARE PREFERENTIALLY WEATHERED, LEAVING A STUBBLED

SURFACE. T H E COLOUR OF THE ROCK IS UNCHANGED IN WEATHERING. I N THIN SECTION, THE

CHLORITE IS SHOWN TO PSEUDOMORPH AFTER AN AMPHIBOLE. T H E PORPHYRITIC MINERALS ARE

ZONED PLAGIOCLASES. THIS ZONING IN THE PLAGIOCLASE LEADS THE AUTHOR TO BELIEVE THAT

THESE PHENOCRYSTS ARE OF IGNEOUS, RATHER THAN OF METAMORPHIC ORIGIN.

T H E PRESENCE OF QUARTZ IN AMYGDULES IS THOUGHT TO B E SECONDARY BECAUSE OF THE

LACK OF POTASSIUM FELDSPAR AS PHENOCRYSTS. THIS ROCK TYPE IS NOTED AS A QUARTZ-

PLAGIOCLASE-HORNBLENDE SCHIST TO THE WEST OF ICE LAKE. H E R E THE AMYGDULES ARE LESS

OBVIOUS AND TEND TO SHOW MORE ELONGATION OF THE QUARTZ AMYGDULES.

A MICROFAULT APPEARS IN A SPECIMEN NEAR THE FOCH RIVER. AMYGDALOIDAL LAVA IS

ALSO LOCATED ON THE SHORE OF THE CENTRAL ARM OF P O P P Y LAKE IN THE NORTH-CENTRAL

PART OF THE AREA. H E R E , THIS AMYGDALOIDAL ROCK IS ASSOCIATED WITH PILLOWED HORN­

BLENDE SCHIST. T H E PILLOWS ARE POOR BUT TOPS COULD B E DETERMINED.

A SIMILAR AMYGDALOIDAL ROCK TYPE WAS REPORTED B Y P Y E ( 1 9 5 7 , P . L L ) IN THE

VICINITY OF SWILL LAKE IN THE ADJOINING MANITOUWADGE AREA.

6

AMPHIBOLITE

This unit is found interbanded or associated with the quartz-plagioclase-hornblende schist. It generally occurs as massive units ranging from 2 to 20 feet in thickness. It is ubiquitous with the hornblende schist and is probably a slightly different phase. It is a dark green, medium- to coarse-grained rock with hornblende generally comprising 85 to 90 percent of the rock and plagioclase with 20 to 25 percent anorthite content being the second main mineral. Weathering tends to colour the rock slightly rusty brown, but with the green colour still predominating.

Unlike the amphibolite noted in the adjoining Manitouwadge area (Pye 1957, p.15), no garnets were noted in this rock. The main accessory minerals are biotite and pyrite, with rare epidote. Sericite is commonly present as the alteration product of plagioclase.

This rock is probably genetically related to the quartz-plagioclase(-chlorite )-hornblende schist. It is thought to be of volcanic origin by its composition, which would approach that of a basalt. Contact relations with the hornblende schist were not defined due to overburden and weathering.

QUARTZ-PL AGIO CLASE(-CHLORITE )-HORNBLENDE SCHIST

This is the main volcanic rock type of the region. It is interbedded with the amphibolite and the amygdaloidal lava. The main occurrence is in the Moshkinabi Lake-Ice Lake-Foch Lake metasedimentary-metavolcanic belt.

Near Moshkinabi Lake the quartz-plagioclase(-chlorite)-hornblende schist is in narrow bands interbedded with the metasediments. The origin here is unknown. According to the government airborne magnetometer survey (ODM-GSC 1962a, b, c, and d) and a ground magnetometer survey, by Falconbridge Nickel Mines Limited, there is a 34 m u < e g aP m t n e belt to the east of Moshkinabi Lake.

Quartz-plagioclase(-chlorite)-hornblende schist is the main rock of the belt, where it reappears 3 miles to the southwest of Ice Lake, and is approximately 1 mile wide at this point. The rock belt follows a northeast strike through to Ice Lake. Granite cuts the metavolcanics several places along the belt. The quartz-plagioclase-hornblende schist contains a large amount of chlorite near the Ice Lake Fault. To the east of Ice Lake the quartz-plagioclase-hornblende schist is found north of a belt of metasediments and narrows from approximately ^2 to J/s mile as it is traced eastwards.

Two miles east of Ice Lake, the volcanic belt disappears and only the meta­sediments continue eastwards to the Foch River. Beyond the Foch River, the quartz-plagioclase(-chlorite)-hornblende schist appears in narrow bands cut by granite or is granitized to a hornblende-biotite-quartz-feldspar gneiss.

In the Poppy Lake area, the various east-west striking volcanic rocks are inti­mately associated, and no attempt was made to sub-divide them here. It must be noted, however, that the quartz-plagioclase(-chlorite)-hornblende schist is pillowed with the tops facing north in the north-central arm of Poppy Lake and is associated with amygdaloidal lava.

In hand specimen, a typical quartz-plagioclase(-chlorite)-hornblende schist is a medium-grained, dark green rock with crosscutting veinlets of quartz. Plagioclase, when its composition could be determined, was found to contain 24 to 28 percent

7

Granitehill Lake Area

ODM8535

PHOTO 1—MINOR FOLDING IN METASEDIMENTS ON THE SHORE OF THE FOCH RIVER NEAR THE ALGOMA-THUNDER BAY BOUNDARY.

anorthite. The plagioclase rarely exceeded 15 percent by volume of the rock, the remainder being hornblende.

In Matthews Township, the quartz-pIagioclase(-chlorite)-hornblende schist gives way to a tremolite-biotite-plagioclase gneiss near a northeast-trending linear cutting through the Olivier occurrence (property 14). Secondary quartz is present with pyrite and a trace of chalcopyrite mineralization.

Metasediments

Metasediments were noted in the Moshkinabi-Ice Lake metasedimentary-meta-volcanic belt mainly on the southern part of the belt to the south of the meta­volcanics. Their age relative to the metavolcanics was not determined. To the east of Ice Lake, the main rock type is a biotite (-hornblende)-quartz-feldspar gneiss in-terbedded with minor quartz-feldspar gneiss and garnet (-biotite)-hornblende-feldspar-quartz schist.

In the northern sector of the area metasediments comprising mainly biotite quartzite interbedded in equal proportion with biotite (-hornblende)-quartz-feldspar gneiss were traced from the west and north of the western part of Fields Lake, through Fields Lake to the east where the metasediments are faulted northward (see Map 2219, back pocket).

8

THE METASEDIMENTS ARE THEN TRACED TO THE NORTH OF POPPY LAKE WHERE THE PREDO­MINANT ROCK BECOMES GARNET-HORNBLENDE-FELDSPAR-QUARTZ SCHIST INTERBEDDED WITH BIOTITE (-HORNBLENDE) -QUARTZ-FELDSPAR GNEISS.

TO THE EAST OF THE FOCH RIVER ALL TYPES OF METASEDIMENTS ARE NOTED IN NARROW BANDS THAT SELDOM EXCEED 4 INCHES IN THICKNESS. THE PREDOMINANT ROCK TYPE IS BIOTITE (-HORNBLENDE)-QUARTZ-FELDSPAR GNEISS WITH LESSER AMOUNTS OF QUARTZ-FELDSPAR GNEISS, BIOTITE QUARTZITE, AND GARNET (-BIOTITE)-HORNBLENDE-FELDSPAR-QUARTZ SCHIST. ON THE LAKE IMMEDIATELY TO THE SOUTHWEST OF SLIPKNOT LAKE, IN FOCH TOWNSHIP, IRON FORMATION IS INTERBEDDED WITH THE METASEDIMENTS. THIS IS A QUARTZ-HORNBLENDE-MAGNETITE IRON FORMATION CONFORMABLE WITH THE METASEDIMENTS.

METASEDIMENTS WERE FIRST NOTED ON THE SOUTHERN BOUNDARY OF THE AREA ALONG THE ALGOMA-THUNDER BAY BOUNDARY BY PARSONS ( 1 9 0 8 ) . THESE ROCKS WERE FOUND TO STRIKE NORTHEASTERLY. METASEDIMENTS WERE ALSO NOTED BY THE AUTHOR AT THE SOUTHERN TIP OF GARNHAM LAKE, WHICH IS OUTSIDE OF THE BOUNDARY OF THE MAP-AREA, BUT IS THE ASSUMED EXTENSION OF THIS ROCK BELT. HERE THE ROCKS ARE THIN-LAYERED BANDS OF QUARTZ-FELDSPAR GNEISS INTERBEDDED WITH BIOTITE QUARTZITE AND DARKER COLOURED BANDS OF BIOTITE (-HORNBLENDE)-QUARTZ-FELDSPAR GNEISS. THE EXTENT OF THIS BELT IS UNKNOWN.

SMALL LENSES OF METASEDIMENTS WITH MINOR METAVOLCANICS WERE NOTED ON STRIKE WITH THE MANITOUWADGE FOLD BELT (PYE 1957 ) .

THREE MAIN LENSES WERE NOTED, ONE JUST NORTH OF THE ONTARIO PAPER COMPANY LIMITED, MANITOUWADGE ACCESS ROAD. HERE THE METASEDIMENTS ARE THIN-BANDED, BIOTITE (-HORNBLENDE)-QUARTZ-FELDSPAR GNEISS AND BIOTITE-QUARTZ-FELDSPAR GNEISS. I N THE SECOND LENS TO THE EAST THE ROCK IS MAINLY BIOTITE-QUARTZ-FELDSPAR GNEISS WITH VERY LITTLE BANDING EVIDENT IN OUTCROPS. THIS UNIT HAS AN APPARENT OFFSET TO THE NORTH WHERE THE BANDED CHARACTER IS MORE PREVALENT AND PYRRHOTITE WAS ENCOUNTERED IN HOLES DRILLED BY FALCONBRIDGE NICKEL MINES LIMITED IN 1965.

BIOTITE QUARTZITE

THIS ROCK IS A QUARTZITE CONTAINING APPROXIMATELY 1 0 PERCENT BIOTITE DISSEMINATED THROUGHOUT. IT IS A MEDIUM-GRAINED ROCK OCCURRING IN BANDS APPROXIMATELY 8 INCHES THICK, AND IS MOST COMMON IN THE FIELDS LAKE AREA. THE BIOTITE QUARTZITE TENDS TO STAND UP IN RELIEF ABOVE OTHER ASSOCIATED METASEDIMENTS BECAUSE OF DIFFERENTIAL WEATHERING AND EROSION. THE QUARTZITE IS WHITE TO CREAM COLOURED AND HAS A PEPPERED LOOK FROM THE BIOTITE. WEATHERING TENDS TO BLEACH THE ROCK. THESE ROCKS ARE FOUND IN SMALL AMOUNTS THROUGHOUT THE AREA.

QUARTZ-FELDSPAR GNEISS

THIS ROCK CAN BEST BE DESCRIBED AS A METAMORPHOSED EQUIVALENT OF ARKOSE. IT COMPRISES QUARTZ 20 PERCENT, MICROCLINE 30 PERCENT, PLAGIOCLASE (An2s) 30 PERCENT, WITH MINOR AMOUNTS EPIDOTE, BIOTITE, CHLORITE, AND SERICITE MAKING UP THE REMAINDER. THE ROCK IS EQUIGRANULAR AND HAS A MASSIVE APPEARANCE. IT GENERALLY OCCURS AS A MINOR MEMBER IN THE ICE LAKE GROUP WITH THE BIOTITE (-HORNBLENDE)-QUARTZ-FELDSPAR GNEISS. THE MAIN OCCURRENCE OF THIS ROCK TYPE IS IN THE SOUTHERN METASEDIMENTARY BELT, WITH THE BEST EXPOSURES ALONG THE SHORES OF SUNDERLAND LAKE. IT OCCURS HERE IN

9

Granitehill Lake Area

BIOTITE(-HORNBLENDE>QUARTZ-FELDSPAR GNEISS

This gneiss is one of the most common metasedimentary rocks that can be found in all major metasedimentary assemblages in the area.

This is a medium-grained, dark coloured rock with lepidoblastic texture, com­monly weathering to a rusty colour due to the chemical breakdown of biotite. It occurs as dark layers interbanded with quartz-feldspar gneiss and commonly with the garnet (-biotite)-hornblende-feldspar-quartz schist. A prime example of this is northwest of the lake found west of Slipknot Lake in central Foch Township.

Near some pegmatitic veins, augite appears as a minor constituent. At other localities the alteration effects are the replacement of biotite by chlorite and plagio­clase by sericite. Both microcline and orthoclase have been noted in different specimens of this rock type.

BIOTITE-QUARTZ-FELDSPAR GNEISS

The biotite-quartz-feldspar gneiss is the least common of the metasedimentary rocks in the area. It is associated with quartz-feldspar gneiss, usually as minor bands in its main occurrence to the west of the Foch River in the northwestern corner of Foch Township. It has been noted in thicker beds up to 10 inches thick in the southern metasedimentary belt, as well as in a minor occurrence bordering granite near where the Algoma-Thunder Bay boundary line crosses the Foch River. Biotite defines the foliation and is also parallel to the remnant bedding.

This gneiss is a medium-grained lepidoblastic rock with weak segregation of minerals, biotite varying from 10 percent to 30 percent modal content in various layers. Quartz occurs as strained grains in narrow stringers, with microcline and lesser plagioclase making up most of the remainder. The plagioclase feldspar grains have a 10 to 30 percent anorthite content and are homogeneous.

Minor constituents are chlorite and sericite, which occur as alteration products of biotite and plagioclase respectively. Magnetite is a common opaque mineral, never exceeding 5 percent in a modal analysis.

GARNET(-BIOTITE)-HORNBLENDE-FELDSPAR-QUARTZ SCHIST

This rock is the most common type of the northern metasediment belt, and is characterized by a porphyroblastic texture with metacrysts of red garnets appearing throughout the beds. These garnets vary in size from %o inch to % inch in diameter. The garnets tend to weather out, leaving rusty coloured cavities in the rock and staining the surrounding area. The rock is dark grey to brown, weathering to a rusty colour on the breakdown of the biotite. It is usually associated with

1 0

bands 8 to 15 inches thick interbedded with minor bands of more biotite-rich meta­sediments showing a salt and pepper texture. Foliation in these rocks is weak. The colour is typically light grey becoming almost white, with weathering and erosion causing the quartz grains to stand out in a mottled effect.

quartz-feldspar gneiss, but associations with other metasedimentary rocks are com­mon. This rock passes into migmatite to the north in the Flanders Lake area (Milne 1964). A full sequence can be observed along the Foch River. This schist is a minor part of the sequence in the Ice Lake area and also was found to occur as minor bands in drill holes near Moshkinabi Lake.

This rock varies in composition with garnet making up from 10 to 15 percent modal quantity in rocks generally containing 20 percent hornblende. The feldspars are microcline and plagioclase. The plagioclase has an anorthite content in the 25 to 35 percent range. Plagioclase makes up from trace amounts to 30 percent of the rock and microcline 5 to 15 percent. Other main minerals are quartz, 15 to 20 percent, and chlorite, 0 to 5 percent. Biotite is formed instead of hornblende when the rock contains an excess of potassium and aluminum. There is a gradation between the two types, which results in both varieties being classified together. It is thought by the author that the variation is due to a difference in clay content of the original sedimentary rock. The chlorite occurs as an alteration of biotite and is present in most specimens.

Minor constituents are magnetite, epidote, sericite, and rare zircons, causing pleochroic holes in the biotite. In one specimen, a trace amount of sillimanite was noted. This was found about % mile east of Ice Lake.

IRON FORMATION

Iron formation occurs on the lake to the west of Slipknot in Foch Township and was not noted elsewhere. It is interbedded with other metasediments and is probably syngenetic.

The iron formation is a dark grey siliceous, magnetic rock very resistant to weathering. It occurs in bands 1% to 3 inches thick, associated with the garnet (-biotite)-hornblende-feldspar-quartz schist and quartz-feldspar gneiss.

It is composed of magnetite up to 10 percent in volume, with quartz, microcline, plagioclase, and biotite making up the remainder.

GARNET-AMPHIBOLE(-CHLORITE>BIOTITE-FELDSPAR SCHIST

This schist is rather rare and occurs as a dark green rock along the northern part of the Foch River where the river takes a sharp bend to the east, and as a somewhat more felsic variety inland from the Foch River in Foote Township in association with the metasediments in the Ice Lake-Moshkinabi Lake belt.

This rock is included with the metasediments, primarily due to its association with the latter. It is a banded rock with the composition of amphibolite and may be a metavolcanic. The thickness of this stratigraphic unit varies from 6 inches to 2 feet. It is possibly a tuff, but microscopic examination revealed no information as to its mode of origin.

Overall composition is that of an intermediate volcanic or of a greywacke. The number of outcrops of this rock type is too few to permit drawing a definite con­clusion as to its original nature.

The rock weathers to a lighter green and garnets tend to leave rusty cavities on the surface.

11

Granitehill Lake Area

Mafic and Ultramafic Intrusive Rocks

ANORTHOSITIC GNEISS1

This rock was found on the east side of Faries Lake and is described by Milne (1968) as an anorthositic gneiss. It is composed of coarse-grained plagioclase of labradorite composition with bands of dark green hornblende giving a foliation parallel to the granodiorite gneiss in the surrounding area. For a full description, the author refers the reader to Milne (1968).

Felsic Intrusive and Metamorphic Rocks

MIGMATITES

The term migmatite has been applied to rocks, in the Granitehill Lake area, in which a granitic component (granite, aplite, pegmatite, granodiorite, or the like) and a metamorphic host rock are intimately admixed on a scale sufficiently coarse for the mixed condition of the rock to be megascopically recognizable.

Migmatites in the Granitehill Lake area are generally classified into two types, the metasedimentary migmatites and the metavolcanic migmatites.

Metasedimentary Migmatites

These rocks are interbanded metasedimentary and granitic material. They can be called lit par lit migmatites. These migmatites are banded with biotite-chlorite gneiss layers alternating with layers of granitic material. Generally, the metasedi­mentary layers show crenulations to a small degree and distinct ptygmatic folds become conspicuous as the granitic part increases, indicating a greater degree of mobilization.

This type of migmatite, as noted in the area bordering the north-central part of the map-area, is probably part of the migmatite complex described by Milne (1964).

1 Although the anorthositic gneiss is rich in neither magnesium or iron, and is not ultramafic in sensu stricto, nevertheless it is thought to be a member of a suite of mafic and ultramafic rocks found in nearby areas and having similar relationships to the Archean metavolcanics and meta­sediments on the one hand and the Archean felsic intrusive and metamorphic rocks on the other. It is included here under the title "Mafic and Ultramafic Intrusive Rocks" to permit a compari­son with the legends accompanying the maps of these surrounding areas, e.g. Milne (1968).

12

The schist is composed of red garnets, biotite or hornblende, and plagioclase (An30-35) with minor quartz and biotite.

Chlorite occurs in the rock as pseudomorphs after biotite and hornblende, in places totally replacing these minerals. In the Ice Lake belt near the Foch River, a large proportion of the feldspar is altered to sericite.

Assemblages encountered were: a) Host rock: Quartz-hornblende-plagioclase (An 4 ) . Granite fraction:

Quartz-microcline-plagioclase (An*), and trace amounts of apatite. b) Host rock: Quartz-chlorite(pseudomorph after biotite )-garnet-

biotite-potassium feldspar-saussuritized plagioclase. Granite frac­tion : Quartz-microcline-plagioclase (saussuritized) - chlorite.

The albite composition of the plagioclase in both fractions leads the author to believe that the metamorphism of the host rock was synchronous with the intro­duction of the granite fraction.

On Tocheri (Sheila) Lake, the metasedimentary migmatites are less common and form a narrow 10-chain wide band striking N50E. Here the metamorphic grade is in the lower granulite fades, probably the biotite-cordierite-almandite sub-facies though no cordierite was noted (de Waard 1965). The assemblage here in the biotite gneiss host rock is biotite-augite-hornblende-plagioclase (An 10_i5)-micro cline-quartz.

The corresponding granite fraction is a quartz monzonite with the assemblage microcline-plagioclase (An22-25) -quartz.

The different anorthite content of the granitic and host rock plagioclase does not preclude the possibility that equilibrium was established. Different plagioclase compositions can occur if an alkali vapour phase was present during the granitiza-tion. In this situation, calcium is the determining factor on the composition of plagioclase since it is not considered a mobile component (Orville 1963). The presence of a vapour phase increases the possibility of sulphide mineralization in local rocks, and could account for the presence of pyrite with traces of chalcopyrite mineralization in the nearby metavolcanic-metasedimentary belt.

Metavolcanic Migmatites

These migmatites differ from the previously described rocks in that the granite fraction does not follow the foliation, but follows joints and other planes of weak­ness. The host rock is the quartz-plagioclase(-chlorite)-hornblende schist or the amphibolite.

The "granite" fraction is pegmatite, made up of quartz, perthite, and minor albite and rare magnetite.

Northward-striking bands of metavolcanic migmatite are present in the northern part of Cecil Township and the southern part of Nickle Township. Thicknesses of the bands are up to Y2 mile. Here the host rock is a hornblende amphibolite. Near the thicker granite veins, augite appears, indicating the metamorphic grade to be that of the granulite facies.

In a second occurrence to the southwest of Poppy Lake, quartz-plagioclase (-chlorite)-hornblende schist grades into metavolcanic migmatite, then into an un­differentiated migmatite where the host rock can no longer be identified because of total granitization.

13

Granitehill Lake Area

HYBRID GNEISS

Hornblende-Biotite-Quartz-Feldspar Gneiss

This is a rock of questionable origin. In the Manitouwadge area, Pye (1957, p.37) included this rock with the metamorphic rocks but concludes that it is a hybrid and stated:

. . . The metamorphic fabric of the rock, the lack of distinct layered structure, the fact that the hornblende schist and the hornblende-biotite-quartz-feldspar gneiss are everywhere conform­able and have gradational contacts, and the fact that in most places the gneiss occupies a position between hornblende schist and granitic rocks, it would thus appear that the gneiss was originally hornblende schist or an equivalent, less highly metamorphosed rock, and that it represents an intermediate hybrid phase in the transformation of the schist to biotite granodiorite gneiss. . . .

This same series was examined by Milne (1968, p.29), and with further studies of similar rock types in the Pic River area and in the northeastern corner of Cirrus Lake, he concluded that:

. . . although the hornblende-biotite grandiorite gneiss may be a hybrid derived by contamin­ation of the biotite granodiorite gneiss with mafic metavolcanic material, it appears to have been mobile and intruded the mafic metavolcanic rocks, and had subsequently been intruded itself by the biotite granodiorite gneiss.

From the author's studies in Nickle Township, the question as to whether the hornblende-biotite-quartz-feldspar gneiss is either igneous, that is contaminated granodiorite, or a metamorphic rock, is inconclusive, since this rock type is, in some places, conformable to the sedimentary rocks, and in other locations, separated from the sedimentary rocks by the granodiorite. Examination of this rock type, on the eastern side of the creek leading into the central west edge of Ice Cream Lake, Herbert Township, shows the gneiss injected into the amphibolite at the contact, supporting Milne's theory as to origin. Further evidence of mobiliation is the presence of inclusions, with gradational contacts, of amphibolite in the hornblende-biotite-quartz-feldspar gneiss.

The rock is composed of biotite, hornblende, plagioclase (An 25-30), microcline, and quartz. Augite occurs in some specimens. It is a fine- to medium-grained rock of greenish grey colour with some pink feldspar grains. Distribution of this rock is in Nickle and Cecil Townships, and it occurs as zones in the biotite granodiorite gneiss, and also as bands conformable to volcanic and metasedimentary beds.

GNEISSIC ROCKS

Biotite Granodiorite Gneiss

This is a gneissic equivalent of the granodiorite, (see section on "Granodiorite and Quartz Monzonite"). Throughout the area, the granodiorite gneiss had blocky inclusions of metavolcanics (Photo 2) and rare stretched inclusions of metasediments.

This rock may be syngenetic with the granodiorite but is described here as a separate rock type following Milne (1968).

The inclusions generally have mineralogical compositions characteristic of the hornblende granulite facies (de Waard 1965), although the corresponding rock 14

ODM8536

Photo 2—Contact between hornblende schist inclusion and granodiorite on the east-central shore of Obakamiga Lake.

types in the "greenstone" belts have compositions characteristic of the amphibolite fades (Fyfe et al. 1958), indicating a change to a higher degree of metamorphism due to the probability that the biotite granodiorite gneiss was formed at a high temperature and crystallized from a magma. The assemblage in the inclusions is augite, plagioclase, and hornblende.

The biotite granodiorite gneiss is a medium to light grey rock weathering to a light pinkish grey. It is medium grained, and in some places has an augen-type structure, but more commonly a lepidoblastic structure. The augen-type structure was noted along the shores of McGraw Lake and other surrounding lakes. It was also found in the gneiss bordering the metasediments in the Moshkinabi Lake area. Here the contact is gradational. In this locality the augen gneiss either was injected into the sediments, or possibly was formed in part at least by alteration of the latter along the boundary of the intrusive granodiorite. As the distance from the metasediments increases, the augen structure disappears and at l/z mile is no longer present.

15

Granite hill Lake Area

Undifferentiated Migmatites

Included in undifferentiated migmatites are rocks in which the granitization has proceeded to a degree where the host rock can no longer be identified as to its origin. Also included in this classification are reported migmatites, from assessment work and other sources that cannot be properly identified.

In outcrop the granitized migmatites are a light pinkish grey rock showing weak banding, which is highly contorted. Individual bands are defined by a concentration of hornblende and magnetite. The composition on the whole is that of a medium-grained quartz monzonite grading to granodiorite in the darker bands.

The main minerals are quartz, 10 to 25 percent; microcline, 30 to 40 percent; plagioclase (An20-30) > 20 to 40 percent; hornblende, 5 to 20 percent. Minor minerals are zircon and magnetite. The main example of the highly granitized migmatite is along the southern shore of the northern part of Granitehill Lake. No attempt was made to correlate these migmatites.

GRANITIC ROCKS

Granite

Massive medium-grained granite, probably slightly younger than the surround­ing granites, was noted over an area not outlined on this scale of mapping, but covering Macutagon Lake, Upper Foch Lake, and Longnega Lake in Roberta and Spooner Townships.

The granite is a light grey rock composed of quartz, microcline, plagioclase (An 2 0 ) , hornblende or biotite.

In the hornblende granite, minor amounts of magnetite, epidote, and sericite are present; the biotite granite has only trace amounts of zircons forming pleochroic haloes in the biotite. No attempt was made to correlate the two varieties of granite.

Granodiorite and Quartz Monzonite

Included in this rock type is granodiorite and some quartz monzonite. The main occurrence of granodiorite is northwest of the central part of Granitehill Lake. Here the rock occurs in hills that parallel the foliation of the surrounding biotite granodiorite gneiss. Other occurrences are in the wide "sills" intruded into the metasediments in the northern part of the area, particularly northern Foch

16

The augen are feldspar, either plagioclase or potassium feldspar. The main constituents of the rock are quartz, plagioclase (An 25_3o), microcline, biotite, a lesser amount of hornblende, and minor amounts of sphene and zircon. A few specimens contain antiperthite as well as plagioclase. The antiperthite is composed of plagioclase (An 15-20) and microcline.

Township. This rock is probably syngenetic with the granodiorite gneiss but is classified separately after Milne (1968).

The composition of this rock is plagioclase (Ani 8_ 25), microcline, lesser quartz, biotite, and hornblende. A characteristic of this rock is myrmekite visible under the microscope. This rock is grey, weathering grey with rare pink stain from microcline weathering; it is medium to coarse grained.

Pegmatite

Granitic pegmatite occurs as veins cutting other rock types and as conformable layers in the migmatites. The pegmatite grains range in size from Vi inch to 3 inches in diameter with the average diameter being 2 inches. Pink perthite is the main mineral making up approximately 50 percent of the rock. Microcline is the host mineral of the perthite with strings of plagioclase of undetermined composition exsolved along the 010 plane. Quartz and albite make up approximately 30 per­cent and 20 percent respectively of the rock. Euhedral magnetite occurs as an accessory mineral in some veins. No ferromagnesian minerals were noted.

Aplite

Aplite occurs as a vein cutting the migmatites and metasediments on the northern shore of Granitehill Lake. The aplite is pink in colour and has a typical "sugar" texture. Veins are 4 to 6 inches in width.

Magnetite-Rich Granite

This is a grey medium-grained granite showing ptygmatic folding where the banding is defined by an alignment of feldspars and biotite. Randomly distributed rounded phenocrysts of magnetite, Vz to 1 inch in diameter, are the main character­istic of this rock. This granite occurs on the eastern side of Foch River where the northern boundary of Foote Township crosses the river. This magnetic granite is represented by an airborne magnetic anomaly of 250 to 300 gammas above back­ground (ODM-GSC 1962c). This is a lineal anomally crossing the area from east to west and probably represents an iron formation completely assimilated by the granite.

The granite is composed of quartz, microcline, plagioclase, biotite, and magne­tite. Minor amounts of epidote and zircon are present.

17

Granitehill Lake Area

PROTEROZOIC

Late Mafic Intrusive Rocks

Dikes of gabbroic composition with ophitic texture (diabase), fine-grained gabbro, and less common porphyritic diabase intrude the Precambrian rocks in all parts of the map-area. Most dikes are 20 to 50 feet wide, though some near the Foch River are 200 feet wide. Some can be traced for 10 miles. One trend is noted to be parallel to the northwest topographic linear system. A secondary set trends north.

The "diabase" rocks weather to a moderate reddish brown, and are generally well jointed. Contact effects are limited to narrow chilled margins within the intrusions. The country rocks are unaffected. The diabases comprise augite, plagio­clase (An4o), magnetite, and minor pyrite, chlorite, and biotite.

The porphyritic variety has plagioclase phenocrysts composed of 65 percent anorthite and groundmass plagioclase of 60 percent anorthite. This variety of diabase has no biotite in it. There are two locations where this type of porphyritic diabase was noted: one is near The Ontario Paper Company Limited road (in northwestern Herbert Township), leading northeast from Camp 70 at \Vi miles from the road intersection north of Camp 70; and the other is located 31/4 miles on azimuth 050° from Camp 70, of The Ontario Paper Company.

An interesting coarse-grained biotite gabbro is found, in Nickle Township, 800 feet on an azimuth of 250° from the southern end of Camp 70. This rock is found on the edge of an outcrop; it shows a fine-grained chill contact in one place and a very coarse-grained pegmatitic grain size a few feet away.

This rock is hypidiomorphic-pegmatitic composed of biotite (7.3 percent), hornblende (50.7 percent), plagioclase (17.8 percent), augite (24.3 percent), and a trace amount of epidote.

A spectrographic analysis on a sample collected by the author and analysed by the Laboratory and Research Branch of the Ontario Department of Mines and North­ern Affairs, gave results in the following ranges: In percent

Chromium 0.05-0.5 Copper 0.01-0.1 Gallium 0.01 or less Manganese 0.1-1 Nickel 0.01-0.1 Vanadium 0.01-0.1

CENOZOIC

Pleistocene

Pleistocene deposits of the Granitehill Lake area can be related to the retreat of the Wisconsin ice sheet (Boissonneau 1966).

18

LEGEND I I Lake Barlcw-Ojibway deposits I J (lake Nakina phase).Lacustrine

deposits; sand, silt, varved clay. I Post-Minong Stage deposits.

I I Lacustrine deposits: modified silly to sandy till. sand.

I Houghton low water stage I deposits.Lacustrine deposits:

varved clay. silt, fine sand. [•'.'•'•] Outwash deposits; fine sand, • "i sand, gravel.

|°°oOo°°| Unmodified till: silly to sandy till.

SYMBOLS

| | Glacial stmt.

Eskers modified by lacustrine action.

Scale in miles

Flgur« 2—Plcinocene gtology of iho Granitehill Lote area (after Boittonmau 1965).

Granitehill Lake Area

From the direction of the eskers, glacial striae, and chatter marks, the trend of the ice movement was to the south-southwest (see Figure 2) .

Ground moraine (Figure 2) covers a band 6 to 10 miles wide on a bearing of northwest to southeast. This is a sandy type of ground moraine containg up to 30 percent boulders of Precambrian granites and gneisses and of fossoliferous Paleozoic dolarenite.

The ground moraine tends to form flat plains, of which the area surrounding Poppy Lake is most typical. The southern part of the area is covered by ground moraine modified by post-Minong Lake action (Boissonneau 1966).

Eskers are prominent features in the area and are used as road beds by The Ontario Paper Company Limited. The eskers usually rise 60 to 100 feet above the surrounding area. An esker "train" follows the Foch River system north to south through the central part of the area. No detailed study was made of the eskers, but composition appears to be crossbedded, fine to coarse sand with a minor quantity of clay towards the top. Eskers in post-glacial lakes are modified by lacustrine action (Boissonneau 1966).

There are sand and gravel deposits that occur in the lower Foch River and Gum River valleys. These are classed as outwash deposits by Boissonneau (1966), though they are made up of glaciofluvial and esker deposits.

Glaciolacustrine deposits are abundant in the map-area. Deposits of fine cross-bedded sands of the Houghton low water stage (Boissonneau 1966) in the Superior Basin are found in Cecil and Nickle Townships, forming a band 1 to 5 miles wide on a bearing of south-southwest. These sand deposits are capped to the south of the area by post-Minong varved clays (Milne 1968). Most of the roads of The Ontario Paper Company Limited are built on these deposits.

Post-Minong deposits are part of a lake stage in the Superior Basin. These deposits are clay and sand overlying ground moraine and cover the southwestern half of the area.

In addition to the glaciolacustrine deposits formed in the Superior Basin, other deposits comprising fine silt and clay were deposited in proglacial Lake Ojibway (Coleman 1909). These deposits occur generally to the north of the height of land across Ontario and form part of the "clay belt".

STRUCTURAL GEOLOGY

The Granitehill Lake area is mostly massive granitic and gneissic rocks that form a batholith, probably part of the batholithic area described by Milne (1968) in the Black River area. In the center of the area is the Moshkinabi-Ice Lake meta-volcanic-metasedimentary belt. This belt is a roof pendant on the batholith and is surrounded by granitic rocks containing fragments of metavolcanic amphibolite and metasediments.

The Moshkinabi Lake part is separated from the Ice Lake part on the Manitou­wadge Lake Aeromagnetic Map (ODM-GSC 1962a) and also on a ground magneto­meter survey map made by Falconbridge Nickel Mines Limited (assessment work files, Ontario Department of Mines and Northern Affairs, Thunder Bay). From this it is assumed that the gap is filled with granitic material.

2 0

In the vicinity of Moshkinabi Lake the metavolcanics and metasediments deline­ate a synform with the southern limb dipping to the north, and the northern limb dipping to the east, resulting in a plunge to the north-northeast. Insufficient struc­tural data prevents a more precise description.

FAULTS

The western limb of the Moshkinabi Lake synform terminates against a fault trending N25W. Metasediments of similar nature reappear on the western side of this fault 3V2 miles to the north in northwestern Herbert Township and cross into Nickle Township. The metasediments are then faulted southward, along the Lucky-shoe Lake Fault, with a throw of % mile. The belt narrows out and is traced westward through a series of lenses to the Manitouwadge fold belt.

Metavolcanics and migmatites crossing Cecil and Nickle Townships on a north-northeast strike are interpreted to have been displaced by the Lome Creek Fault. Movement was dextral with displacement, of the north side, being approximately VA miles to the southeast. A second displacement followed along the Luckyshoe Lake Fault. Apparent displacement on the east side of Luckyshoe Lake Fault is approximately \Vx miles to the south. This displaced part of the belt has a north­east strike and the belt terminates against the Ice Cream Lake Fault (see Map 2219, back pocket).

There are two main sets of faults, one set on a northwest trend, and a second set trending north, in places arching to the northeast. There is insufficient data to state which is the older set.

The area is cut by numerous topographic lineaments parallel to the fault systems and these are probably compatible structures. Many of the linears are weathered-out diabase dikes, others are joints.

One arching set of lineaments, in the vicinity of Upper Foch Lake (in Roberta and Spooner Townships), is in the massive granite area. These lineaments probably represent tension joints after intrusion and solidification.

Schistosity and gneissosity in the metavolcanics and metasediments tend to be parallel to the remnant bedding. Gneissosity in the granodiorite gneiss trends to the north or northeast.

ECONOMIC GEOLOGY

In the Granitehill Lake area, sulphide mineralization was noted mainly in meta­sedimentary layers. In all examples observed by the author, pyrite, pyrrhotite, and trace chalcopyrite occur as a replacement within the host rock. Where surface examination was possible at Moshkinabi Lake, Ice Lake, west of the Foch River, and at the Olivier occurrence, the sulphide zones were stratigraphically controlled and in metasedimentary rocks. No vein filling or other types of mineralization were noted. Metals detected in measurable quantities at the above-mentioned locations were copper, silver, and gold. Trace quantities of lead and nickel were also detected. The only other mineralization observed was disseminated pyrite in the diabase dikes.

21

Granitehill Lake Area

The sulphide mineralization is thought by the author to have possibly been deposited by an alkali halide vapour* phase.

Evidence for the presence of such an alkali vapour phase is as follows:

a ) The "lit par lit" migmatites, in the area studied, generally lack igneous features such as chilled margins or contact metamorphic effects between the "granitic" and metamorphic phases. The sug­gested origin of the "granitic" phase, without recourse to melting or partial melting of the host rock, is by metamorphism of a layered host rock, probably a sediment, by the introduction of an alkali vapour phase, related to the late granite intrusives.

The existence of alkali halides in nature has been shown by analysis of fluid-filled inclusions in minerals (Roedder 1958).

Orville (1963) as the result of experimental work in the system KAlSi 308-NaAlSi308-NaCl-KCl-H 20 and subsequently with the addition of Ca-feldspar to the system demonstrated that the existence of two volumes of rock of different bulk composition and in apparent chemical equilibrium can be achieved by metamorphism in the presence of an alkali vapour phase. In this case the quan­tity of calcium in the original rock, assuming a constant temper­ature and pressure, will result in compositional gradients with respect to alkalies in the vapour phase that will favor alkali meta­somatism during metamorphism. Rocks originally rich in Ca will tend to be depleted in K-feldspar, and rocks poor in Ca will tend to be enriched in K-feldspar. This will result in one phase having a predominance of K-feldspar and will appear to be granitic and the Ca-rich rock will lack K-feldspar and tend to be mafic.

In his conclusions, Orville (1963) stated that: During regional metamorphism the vapour phase probably plays an

essentially passive role and serves as medium for diffusion of ions in re­sponse to concentration gradients established by reactions between cyrstalline phases and ion in solution. On the other hand, during contact metamorphism and hydrothermal alteration associated with ore deposition, the vapour phase may be an active transporting agent of alkalies.

Conformation of this theory of migmatite origin in this area could be achieved by a detailed study of both types of feldspars in the migmatites and comparing the results to the existing experi­mental results; a study beyond the scope of this report.

b ) The mineralized rocks in the Manitouwadge and Granitehill Lake areas show that when partial replacement of the host rock takes place, it is a feldspar that is replaced (Pye 1957; and this report, the section on "Ice Lake Deposit").

Most sulphide minerals in the immediate and adjoining areas occur in metasediments. As sediments tend to have alkali rather than calcic feldspar, these rocks would tend to be sulphide host

*The term vapour is used for lack of a better term since we are probably dealing with water above the critical point, that is 374.0°C at a confining pressure of 224.9 Kg/cm 2 (a depth of less than 1 mile.)

2 2

rocks in the case of alkali halide vapour phase transport during contact metamorphism. Because of their porosity, and the avail­able alkali feldspars, the sediments would be the initial replace­ment zone for the alkali halide vapour phase possibly carrying the sulphide minerals,

c) Finally, the age determinations on the Manitouwadge ore by lead isotope ratios indicates that the ores coincide with the late granite phase (Pye 1957, p.74), which would be the source of the alkali vapour phase.

This is a simplified version of the possible activity of volatile constituents derived from granitic differention during cooling but more work should be done on the function of these constituents in relation to the origin of ore deposits.

RECOMMENDATIONS TO PROSPECTORS

On theoretical grounds, the most suitable rocks for sulphide occurrences appear to be the metasediments of the area (see above). The metavolcanics were found to be deficient in sulphide minerals and only the more felsic varities are considered by the author to be favourable host rocks.

Other possible locations of sulphide mineralization are in the numerous topo­graphic lineaments crossing the area including the metasedimentary and metavol­canic belts. These lineaments are as a rule topographic depressions covered by over­burden. They are the topographic expression of eroded "diabase" dikes, joints, and fault zones.

DESCRIPTIONS OF PROPERTIES AND OCCURRENCES

Conwest Exploration Company Limited [1954] * (1) * *

Conwest Exploration Company Limited submitted assessment work on 18 contiguous claims in Nickle Township immediately southwest of Luckyshoe Lake. An aeromagnetic survey compiled at a scale of 1 inch to VA mile with flight lines at VA mile intervals was flown in April 1954. This survey was followed up in August by a geological survey. No economic occurrences of minerals were located and the claims were allowed to lapse in September 1956.

*Date in square brackets refers to date of last major work. **Number in brackets refers to property number on Map 2219, back pocket.

2 3

Granitehill Lake Area

INFORMATION FOR THE GRANITEHILL LAKE AREA ON FILE WITH THE RESIDENT GEOLOGISTS OF THUNDER BAY AND SAULT STE. MARIE AS OF 31 DECEMBER 1967

Company File Date Type of Work

Conwest Exploration Co. Ltd. Thunder Bay 1954 Geological

Thunder Bay 1954 Aeromagnetic

Delmico Mines Ltd. SSM-1042 1963 Electromagnetic

Thunder Bay 1963 Electromagnetic

Falconbridge Nickel Mines Ltd.

SSM-1052

Thunder Bay

1964

1965

Geological

Diamond drilling

Thunder Bay 1967 Electromagnetic

Thunder Bay 1967 Magnetometer

Thunder Bay 1967 Geological

Gavan Mines Ltd. Thunder Bay 1954 Diamond drilling

Thunder Bay 1960 Diamond drilling

Marlhill Mines Ltd. SSM-1349 1955 Geological

Thunder Bay 1955 Geological

Thunder Bay 1958 Diamond drilling

Mining Corporation of Canada Ltd., The

Thunder Bay

Thunder Bay

1955

1958

Geological

Geological

Thunder Bay 1958 Electromagnetic

Thunder Bay 1958 Magnetometer

Thunder Bay 1959 Diamond drilling

Thunder Bay 1961 Diamond drilling

New Fortune Mines Ltd. Thunder Bay 1954 Geological

Ontario Paper Company Ltd., The

SSM-1347 1958 Geological

Selco Exploration Co. Ltd. Thunder Bay 1955 Diamond drilling

Thunder Bay 1955 Geological

Timmins, N. A., Explorations (Ontario) Ltd.,

Thunder Bay 1954 Aeromagnetic Timmins, N. A., Explorations (Ontario) Ltd.,

SSM-1348 1954 Aeromagnetic

Thunder Bay 1954 Geological Trans-Dominion Mining

and Oils Corporation Thunder Bay 1954 Geological

2 4

Delmico Mines Limited [1963] (2)

Delmico Mines Limited reported assessment work on a group of 45 contiguous claims located at the corner of three townships; Foote Township (District of Thunder Bay), Drew and Foch Townships (District of Algoma). An electromag­netic survey was conducted in 1963 over the property at a grid interval of 400 feet. Three anomalies were outlined of which two were too weak to be of signifi­cance although a third one located 1V6 miles southwest of the bottom of Foch Lake was thought to be caused by pyrite-pyrrhotite mineralization. No further work was reported and the claims were cancelled in 1964.

Falconbridge Nickel Mines Limited (3, 4, 5, 6)

As of August 1967, Falconbridge Nickel Mines Limited, held three blocks of claims in the Granitehill Lake area; one group of 30 claims in Herbert Township, one group of 51 claims in the Moshkinabi Lake area (Herbert and Roberta Town­ships), and a third group of 55 claims covering Ice Lake to Foch Lake (described as two groups) in the southeastern corner of Herbert Township and southwestern corner of Foote Township. The company has followed an exploration sequence of ground geophysical work followed by drilling of anomalies and subsequent geological mapping. The claims were in good standing at the time of investigation by the author.

MOSHKINABI LAKE DEPOSIT (3 )

The Moshkinabi Lake copper deposit is in a sheared biotite (-hornblende)-quartz-feldspar gneiss about 5,000 feet, S20W from the southwestern corner of Moshkinabi Lake. It was first staked in the summer of 1964, by Falconbridge Nickel Mines Limited, as part of a general exploration program of the area. Subsequent electromagnetic and magnetometer surveys the following winter outlined an anomaly, which was drilled in the summer of 1965. Seven holes totalling 2,463 feet were drilled on this anomaly, cutting sulphide minerals in all holes over core lengths averaging 10 feet. No assay results are available from the drill holes (see Figure 3). Three trenches 400 feet apart across the anomaly zone, each about 20 feet long by 3 feet wide, cut the sulphide zone.

In trench No. 1, (the northernmost) the rock has approximately 30 percent sulphide minerals occurring in stringers parallel to the foliation. Chalcopyrite com­prises less than 1 percent of the sulphide minerals. A grab sample taken by the author, and analyzed by the Laboratory and Research Branch of the Ontario Depart­ment of Mines and Northern Affairs, shows only trace amounts of gold, silver, cop­per, and lead. At trench No. 2, the rock appears to be a quartz-feldspar-hornblende gneiss with what appears to be two phases of quartz, one primary and a second, post-sulphide mineralization. Here the mineralization is pyrrhotite-pyrite-chalcopyrite occurring as a replacement in stringers. Here a grab sample taken by the author, and analyzed by the Laboratory and Research Branch of the Ontario Department of Mines and Northern Affairs, showed only trace amounts of gold, silver, copper, and lead.

2 5

rO

\80<

LEGEND

PEGMATITE.

GRANITE.

A) QUARTZ-FELDSPAR AUGEN GNEISS. B) MIGMATITE: AUGEN GNEISS AND METASEDIMENTS. METASEDIMENTS: BIOTITE QUARTZITE, QUARTZ-FELDSPAR GNEISS, BIOTITE (-HORNBLENDE) -QUARTZ-FELDSPAR GNEISS, BIOTITE-QUARTZ-FELDSPAR GNEISS, GARNET-BIOTITE- HORNBLENDE-FELDSPAR-QUARTZ SCHIST. BLACK LINE REPRESENTS SULPHIDE ZONES OF PYRRHOTITE, PYRITE, AND TRACE CHALCOPYRITE IN METASEDIMENTS. HORNBLENDE-PLAGIOCLASE GNEISS (METADIORITE).

S Y M B O L S

BEDDING PLANE (INCLINED).

GEOLOGICAL BOUNDARY (INTERPRETED).

TRENCH.

DIAMOND DRILL HOLE.

CLAIM LINE (UNSURVEYED).

200 i—i

Scale in feet

200 _ L _

400 l_

600

O.D.M. 6441

Q 3

Q 7C O

Figure 3—Moshkinabi Lake deposit in Granitehill Lake area (Falconbridge Nickel Mines Limited) from company plans.

The mineralization in the third trench is much the same as that in trenches No. 1 and No. 2, with only trace amounts of gold, silver, copper, and lead.

I C E L A K E D E P O S I T (4)

This deposit was originally trenched by Delmico Mines Limited in 1955. The trench is 150 feet long across the strike of the enclosing metasediments. The host rock here is a biotite (-hornblende)-quartz-feldspar schist. The rock at the northern end of the trench is mineralized by pyrite. This grades to pyrrhotite, with minor chalcopyrite, in the rock at the southern end of the trench over a width of 10 feet.

The sulphide minerals occur as a replacement of feldspars. A grab sample of a specimen showing chalcopyrite was taken by the author and an analysis by the Laboratory and Research Branch of the Ontario Department of Mines and Northern Affairs indicated 0.11 percent copper and a trace amount of nickel. No further work is being carried out at present.

F O C H R I V E R D E P O S I T (5 )

This deposit was first discovered by David R. Bell of Falconbridge Nickel Mines Limited, in the summer of 1967. The mineralization is a replacement type in narrow beds of garnet-quartz-amphibolite-biotite-feldspar schist. These layers are interbedded with a felsic garnet-amphibole-biotite-quartz-feldspar schist, which has only trace amounts of mineralization. Two visible mineralized beds averaging 4 inches wide can be traced for 150 feet along a strike of N55E. Dip for the beds here is 60N, but is not shown on Map 2219, (back pocket). Analysis by the Laboratory and Research Branch of the Ontario Department of Mines and Northern Affairs of a grab sample indicated, copper 0.56 percent, silver 0.15 ounces per ton, with trace amounts of gold, lead, nickel, and vanadium. Only minor surface stripping has been done at present.

H E R B E R T T O W N S H I P D E P O S I T (6 )

This deposit occurs on a group of 30 contiguous claims in west-central Herbert Township, 3Vi miles due east of Luckyshoe Lake. Eight exploratory holes were drilled in 1965, totalling 2,814 feet, to check the results of ground magnetometer and electromagnetic survey. Sulphide minerals encountered in the metasediments in seven of the holes were pyrrhotite and minor pyrite. Grade ranged from 5 percent to 90 percent total sulphides over an average width of 23 feet. Only a trace of chal­copyrite was located in hole number six. The length tested was about 1,000 feet and the altitude of the mineralized zone was vertical to near vertical. The claims were in good standing in August 1967.

27

Granitehill Lake Area

Gavan Mines Limited [1960] (7)

Twenty contiguous claims were held on the border of Gemmell and Nickle Townships by Gavan Mines Limited, from 1954 until cancellation in 1965. Seven holes drilled in 1954, totalling 2,000 feet, intersected sulphide mineralization in four holes. Width varied from 3 feet to 35 feet but continuity was lacking. From 5 percent to 30 percent pyrrhotite and pyrite mineralization was encountered with a trace of galena and sphalerite found in hole No. 2.

A further 12 holes totalling 1,202 feet were drilled for assessment credit in 1960. Only minor disseminated pyrite was encountered with trace chalcopyrite in one hole.

Marlhill Mines Limited [1958] (8)

Marlhill Mines Limited held nine claims in the vicinity of Lome Lake (Nickle Township) and carried out a geological survey at 1 inch to 200 feet. Four holes were drilled in 1958 cutting only disseminated pyrrhotite-pyrite and a trace of chal­copyrite in metasediments. Total footage was 2,400 feet. Claims were cancelled in November 1958.

Mining Corporation of Canada (1964) Limited* (9, 10, 11, 12)

BOOT LAKE GROUP [1955J (9)

The Mining Corporation of Canada Limited, in 1955, geologically surveyed a group of 36 claims located along Fox Creek, immediately north of the northwestern corner of Nickle Township. Nothing of economic interest was located and the claims were allowed to lapse in 1955.

WOWUN LAKE, GROUP NO 1 (10)

The Mining Corporation of Canada (1964) Limited owned, in 1967, 20 leased claims in southwestern Nickle Township. These claims were leased in 1964. Work reported for assessment credit includes, geological, eletromagnetic, and magneto­meter surveys, all done in 1958, and drilling carried out in 1959 and 1961.

The magnetometer survey indicated the presence of three linear anomalies strik­ing across the surveyed area at approximately N75E and approximately 2,000 feet apart. The southernmost anomaly has for surface expression the hornblende-biotite-quartz-feldspar gneiss and the two others are caused by metasediments composed of biotite (-hornblende)-quartz-feldspar gneiss and biotite-quartz-feldspar

*Work completed by both The Mining Corporation of Canada Limited and the Mining Corporation of Canada (1964) Limited is reported in this section.

28

gneiss. The magnetometer survey also outlined three diabase dikes striking at N40W and approximately 1,000 feet apart. Two were noted on the surface.

Two electromagnetic surveys were made, one to the east of the leased claims and one covering the presently leased claims. The electromagnetic survey covering the unleased claims revealed no conductors. The survey over leased claims showed a conductor in claim TB91587, and another in claim TB91557. Both these conductors were drilled in 1959.

Drill hole No. MI-2 to test the electromagnetic anomaly in claim TB91587 intersected traces of disseminated pyrite in biotite-quartz-feldspar gneiss at depths in the hole of 35.5 feet to 53.3 feet, 96.8 feet to 116.0 feet, and 123.0 feet to 158.0 feet. Traces of chalcopyrite and pyrrhotite were noted in pegmatite between 159.2 feet and 161.0 feet. Chalcopyrite was found disseminated in white quartz from 201.4 feet to 204.4 feet, and from 207.2 feet to 209.6 feet. Traces of pyrite-chalcopyrite are finally reported in migmatized biotite-quartz-feldspar gneiss between footages of 209.6 feet and 218.7 feet. No assay results are available.

Drill hole No. MI-4 to test the electromagnetic anomaly on claim TB91557 indicated only trace pyrite in the bands of biotite-quartz-feldspar gneiss. No chal­copyrite was noted. No assay results are available.

Drilling totalled 2,553 feet for seven holes. Surface examination of the property showed that the area is underlain by biotite

granodiorite gneiss with the two bands of metasediments, one of biotite (-horn­blende)-quartz-feldspar gneiss. Only trace amounts of pyrite were found in the biotite-quartz-feldspar gneiss with the smaller bands of biotite (-hornblende)-quartz-feldspar gneiss. No economic amounts of minerals were observed.

LUCKYSHOE LAKE, GROUP NO. 2 [1958] (11)

The Mining Corporation of Canada Limited held a group of 28 claims west of Luckyshoe Lake. A geological survey in 1958 was submitted for assessment. The claims were then allowed to lapse in October 1959.

GROUP NO. 3 [1958] (12)

A group of 24 claims were geologically surveyed in 1958 by The Mining Corpor­ation of Canada Limited. The claims were located immediately east of the present Falconbridge Nickel Mines Limited, Herbert Township property. The survey out­lined on the surface the paragneiss intersected in drilling by Falconbridge Nickel Mines Limited. The claims were subsequently allowed to lapse in October 1960.

New Fortune Mines Limited [1954] (13)

New Fortune Mines Limited held 26 contiguous claims in the southwestern corner of Nickle Township. A geological survey in 1954 failed to reveal any eco­nomic mineralization and the claims were allowed to lapse in 1955.

2 9

Granitehill Lake Area

T h e Ontario Paper Company Limited

The Ontario Paper Company Limited, in 1958, geologically surveyed, at a scale of 1 inch to 2 miles, their timber limits in the Kapuskasing Adminsitrative District of the Ontario Department of Lands and Forests. A copy was donated to the Ontario Department of Mines.

Selco Exploration Company Limited [1955] (15)

Selco Exploration Company Limited held 54 contiguous claims, in 1955, im­mediately north of the northeastern corner of Nickle Township. A geological survey and drilling of 19 short holes, averaging less than 20 feet in depth, failed to reveal any minerals of economic interest. The claims were allowed to lapse in January 1956.

N.A. Timmins Explorations (Ontario) Limited [1954] (16)

N. A. Timmins Exploration (Ontario) Limited held 27 contiguous claims around Foch Lake. In 1954 an aeromagnetic survey was flown and compiled at a scale of 1 inch to 600 feet. This was followed up by a geological survey the same year and compiled at a scale of 1 inch to 400 feet. The claims were allowed to lapse in Sep­tember 1955.

Trans-Dominion Mining and Oils Corporation [1954] (17)

Twenty contiguous claims were held by this company on the corner of Gertrude, Nickle, and Cecil Townships. The area was geologically surveyed in 1954. The claims were allowed to lapse in October, 1958.

30

Olivier Occurrence (14)

A showing in north-central Matthews Township, brought to the attention of the author by M. Olivier, occurs at the bottom of a cliff face where pyrite and a little chalcopyrite replaces felsic minerals in a hornblende amphibolite. Work at present consists of a blast hole from which a grab sample taken by the author, and analysed by the Laboratory and Research Branch of the Ontario Department of Mines and Northern Affairs, indicated 0.01 ounce per ton of gold and 0.31 ounce per ton of silver. Only trace amounts of copper were present. At present no other work has been done on this showing.

SELECTED REFERENCES

Boissonneau, A. N. 1965: Algoma-Cochrane, surficial geology; Ontario Dept. Lands and Forests, Map S365,

scale 1 inch to 8 miles. Surficial geology 1962 to 1963. 1966: Glacial history of northeastern Ontario. 1. The Cochrane-Hearst area; Canadian J .

of Earth Sci., Vol. 3, No. 5, p.559-578. Coates, M. E.

1968: Geology of Stevens-Kagiano Lake area; Ontario Dept. Mines, GR68, 22p. Accom­panied by Maps 2140 and 2141, scale 1 inch to 1 mile.

Coleman, A. P. 1909: Lake Ojibway; Last of the great glacial lakes; Ontario Bur. Mines, Vol. 18, pt. 1,

p.284-293. de Waard, Dirk

1965: A proposed subdivision of the granulite facies; American J . Sci., Vol. 263, No. 5, p.455-461.

Fenwick, K. G. 1967: Geology of the Dayohessarah Lake area; Ontario Dept. Mines, GR49, 16p.

Accompanied by Map 2129, scale 1 inch to 2 miles. Fyfe, W. S., Turner, F. J . , Verhoogen, J .

1958: Metamorphic reactions and metamorphic facies; Geol. Soc. America, Mem. 73, 259p. Leech, G. B., Lowdon, J . A., Stockwell, C. H., and Wanless, R. K.

1963: Age determinations and geological studies (including isotopic ages-report 4 ) ; Geol. Surv. Canada, Paper 63-17, 140p. Accompanied by 5 figures.

Lowdon, J . A., compiler 1961: Age determinations by the Geological Survey of Canada, report 2: isotope ages; Geol.

Surv. Canada, Paper 61-17, 127p. Accompanied by 2 figures. Milne, V. G.

1964: Geology of the Flanders Lake area; Ontario Dept. Mines, GR21, 18p. Accom­panied by Map 2047, scale 1 inch to 1 mile.

1968: Geology of Black River area; Ontario Dept. of Mines, GR72, 68p. Accompanied by Maps 2143, 2144, 2145, 2146, and 2147, scale 1 inch to Vx mile.

ODM-GSC 1962a: Manitouwadge Lake Sheet, Thunder Bay District, Ontario; Ontario Dept. Mines-

Geol. Surv. Canada, Aeromagnetic Series Map 2169G, scale 1 inch to 1 mile. Survey April to October 1962.

1962b: White Otter River Sheet, Thunder Bay District, Ontario; Ontario Dept. Mines-Geol. Surv. Canada, Aeromagnetic Series Map 2170G, scale 1 inch to 1 mile. Survey April to October 1962.

1962c: Obakamiga Lake Sheet, Algoma and Thunder Bay Districts, Ontario; Ontario Dept. Mines-Geol. Surv. Canada, Aeromagnetic Series Map 2180G, scale 1 inch to 1 mile. Survey April to October 1962.

1962d: Nagagami Lake Sheet, Algoma and Thunder Bay Districts, Ontario; Ontario Dept. Mines-Geol. Surv. Canada, Aeromagnetic Series Map 2181G, scale 1 inch to 1 mile. Survey April to October 1962.

Orville, Phillip M. 1963: Alkali ion exchange between vapour and feldspar phases; American T. Sci., Vol. 261,

No. 3, p.201-237. Parsons, Arthur L.

1908: Geology of Thunder Bay-Algoma boundary; Ontario Bur. Mines, Vol. 17, p.95-135. Pye, E. G.

1957: Geology of the Manitouwadge area; Ontario Dept. Mines, Vol. 66, pt. 8, 114p. (published 1960). Accompanied by Map 1957-8, scale 1 inch to Vi mile.

Roedder, Edwin 1958: Technique for the extraction and partial chemical analysis of fluid filled inclusions

from minerals; Econ. Geol., Vol. 53, p.235-269.

31

I N D E X

PAGE Abitibi Power and Paper Co. Ltd 1,3 Acknowledgments 2 Age determination of rocks, notes 4

Table 6 Amphibolite 7, 14, 20 Amphibolite facies rocks 4, 15 Amygdaloidal lava 6, 7 Analyses, notes and table 18, 30 Aplite 12, 17 Archean rocks 6-17 Arkose 9 Assessment work, table 24 Batholith 4, 20 Bell. David R.:

of Falconbridge Nickel Mines Ltd 27 Black River area 1 Boot Lake group, claims 28 Cecil Tp 1, 13, 14, 21, 30 Cenozoic 18-20 Chalcopyrite 3, 8, 13, 21, 25, 29, 30 Cholette Tp 3 Chromium, in table 18 Clay 20 Colour phases in rocks:

Amphibolite 7 Alpite 17 Granodiorite 17

Conwest Exploration Co. Ltd 3, 23 Assessment work, table 24

Copper 18, 21, 27 Trace 25, 30

Dayohessarah Lake 1, 4 Delmico Mines Ltd 3, 25, 27

Assessment work, table 24 Diabase 18

Dikes 4, 21, 29 Dikes, diabase 4, 21, 29 Drew Tp 3, 25 Economic geology • • -21-30 Epidote 7, 9, 11, 16, 17, 18 Eskers t 20 Exploration, recommendations for 23 Falconbridge Nickel Mines Ltd. . . 3, 20, 25, 27 29

Assessment work, table 24 Faries Lake 12 Faults 7, 21 Fields Lake 8, 9 Fish and game 3 Flanders Lake 1, 4, 11 Foch Lake 1, 3, 4, 6, 7, 25 Foch River 1, 2, 10, 17, 18, 20, 21 Foch River deposit 27 Foch Tp 3, 9, 10, 11, 25 Foote Tp 3, 11, 17, 25 Fox Creek 28 Galena 28 Game and fish 3 Garnet 10, 12 Garnham Lake 9 Gavan Mines Ltd 3, 28

Assessment work, table 24 Geco Div., Noranda Mines Ltd 3

PAGE Gemmell Tp 3, 28 General geology 4-20 Geology:

Economic 21-30 General 4-20 Structural 20-21

Gertrude Tp 30 Glaciofluvial deposits 20 Gneiss 8, 9-10, 12, 13, 17, 29 Gneissic rocks 14-16 Gold 21, 25, 27, 30 Granite 7, 10, 12, 16-17 Granodiorite 12, 14, 15, 16 Gravel and sand deposits 20 Gum River 1, 2 Gum River valley 20 Herbert Tp 2, 3, 4, 14, 21, 25, 29 Herbert Tp. deposit 27 Ice Cream Lake 14 Ice Cream Lake Fault 21 Ice Lake 3, 6, 7, 8, 11, 20, 25 Ice Lake belt 4, 12 Ice Lake deposit 27 Ice Lake Fault 7 Inftusive rocks 12-17, 18 Kenogami River 2 Keweenawan rocks 4 Lake Ojibway (proglacial) 20 Lead 21, 25, 27 Lessard Tp 4 Lithologic units, table of 5 Longnega Lake 16 Lome Creek Fault 21 Lome Lake 28 Luckyshoe Lake 23

Claims 29 Luckyshoe Lake Fault 21 McGraw Lake 15 Macutagon Lake 16 Magnetite 10, 11, 13, 16, 17, 18 Manganese, in table 18 Manitouwadge area 1, 9 Mapping, notes 2 Maps:

Geological, coloured back pocket Marlhill Mines Ltd 3 ,28

Assessment work, table 24 Matthews Tp 3, 4, 8, 30 Metasedimentary-metavolcanic belt . . 7 , 8, 13, 20 Metasediments 8-12, 21, 28

Photo 8 Metavolcanic-metasedimentary belt . . 7, 8, 13, 20 Metavolcanics 5, 21 Migmatites 4, 12-13, 17, 21 Mining Corp. of Canada Ltd., The 3, 28, 29

Assessment work, table 24 Mining Corp. Canada (1964) Ltd.:

Properties 28-29 Monzonite, quartz 13, 16 Moraine 20 Moshkinabi Lake 4, 7, 11, 15, 20, 21 Moshkinabi Lake deposit 25

Figure 26

3 2

PAGE Nagagami Lake 1 Natural resources 3 New Fortune Mines Ltd 3, 29

Assessment work, table 24 Nickel 18, 21, 27 Nickle Tp 1, 3, 4, 21, 23, 30 Noranda Mines Ltd. (Geco Div.) 3 Obakamiga Lake 1 Obakamiga River 1 Occurrences 8, 21, 23-30 Ojibway, Lake (proglacial) 20 Olivier, M 30 Olivier occurrence 8, 21, 30 Ontario Paper Co. Ltd., The . . 1 , 3 , 9, 13, 20, 30

Assessment work, table 24 Osawin River 2 Pegmatite 12, 17, 29 Pillowed rocks 6, 7 Pleistocene deposits 18-20

Figure 19 Poppy Lake 2, 4, 6, 7, 9, 13, 20 Precambrian rocks 18 Properties, descriptions of 23-30 Proterozoic rocks 18 Pyrite 7, 13, 18, 25, 27, 28, 30 Pyrrhotite 9, 25, 27, 28, 29 Quartz monzonite 13, 16 Quartz veinlets 6, 7 Roberta Tp 2, 4, 16, 25 Sand and gravel deposits 20 Schists 6, 7-8, 9, 10, 15, 27 Selco Exploration Co. Ltd 3, 30

Assessment work, table 24

PAGE

Shabotik River 1, 4 Sheila Lake:

See: Tocheri Lake Silt 20 Silver 21, 25, 27, 30 Slipknot Lake 9, 10, 11 Sphalerite 28 Sphene 16 Spooner Tp 2, 16 Structural geology 20-21 Sulphide mineralization 13, 22, 25, 27, 2!\

See also: Chalcopyritej Galena; Pyrite; Pyrrhotite; Sphalerite.

Sunderland Lake 9 Surveys, geophysical, notes 25, 27, 28, 29 Timmins, N.A., Explorations (Ontario) Ltd. 3, 30

Assessment work, table 24 Tocheri Creek 2 Tocheri (Sheila) Lake 13 Trans-Dominion Mining and Oils Corp 3, 30

Assessment work, table 24 Tuff 11 Upper Foch Lake 16, 21 Vanadium 18, 27 Varved clay 20 Veinlets, quartz 6, 7 Volcanic rocks 7

See also: Metavolcanics. White Lake 1 White River 1 Wowun Lake, claims 28 Zircon 11, 16, 17

3 3