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ONTARIO DEPARTMENT OF MINES
HON. G. C. WARDROPE, Minister D. P. DOUGLASS, Deputy Minister
J. E. THOMSON, Director, Geological Branch
Geology of the
Dayohessarah Lake AreaDistrict of Algoma
By
K. G. FENWICK
Geological Report 49
TORONTO 1967
Crown copyrights reserved. This book may not be reproduced, in whole or in part, without the permission of the Ontario Department of Mines.
Publications of the Ontario Department of Mines
and pricelists
are obtainable through the
Publications Office, Ontario Department of Mines
Parliament Buildings, Queen's Park
Toronto, Ontario, Canada.
Orders for publications should be accompanied by cheque, or money order,payable in Canadian funds to Treasurer of Ontario.
Stamps are not acceptable.
2,000—E16—1967
CONTENTS
PAGEAbstract... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . ivI ntroduction.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . l
Acknowledgments. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . lMeans of Access. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . 2Previous Geological Work. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 2Topography and Drainage..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Amount and Distribution of Outcrop. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 3Natural Resources. . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . 3
Forests and Lumbering. . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. . . . . . . . . . . . . . . . . . . . . . . . . 3Fish and Game. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Tourism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . . 3
General Geology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Table of Formations..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 4
Metavolcanics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Metasediments..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . .. . . . 7Basic Intrusive Rocks. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Granitic Rocks. . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Keweenawan. . . . ... . . . . . . . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . ... . . . . . . .. . . ... . . .. . . .. 12Pleistocene and Recent. . . . . . . . . . . .. . . .. . . .. . ... . . .. . . . . . . .. . . .. . . . ... ... . . . .. . . . 13
Structural Geology. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . 13Economic Geology.... . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Selected References.. . . . . . . . . .. . . . . . . . . . . . .. .. . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Index................... ........ . ... . ... . ... . ... ... . . . .. . . .. . . .. . .... . . . . . . . . . . . .. . 15
Table
1-Age Determinations. . . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Photographs1-Metavolcanic rock cut by pegmatites and quartz stringers, Dayohessarah Lake..... . . . . . . . . 72-Garnetiferous biotite schist, island in Dayohessarah Lake. . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . 83-Squeezed conglomerate, island in Dayohessarah Lake.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94-Intense shearing in metasediments, Dayohessarah Lake. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95-Coarse-grained pegmatite ...........................................................116-Breccia-type migmatite. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure1-Key map showing location of map-area..... . . . . . . .. . . .. . ....... . . . . . . . . . . . . . . . . . . . . . . . iv
Geological Map (back pocket)
Map 2129 (coloured)-Dayohessarah Lake area, District of Algoma. Scale, l inch to 2 miles.
in
ABSTRACT
The geology of the Dayohessarah Lake area was mapped during the field seasons of 1963 and 1964. The mapping was mostly reconnaissance in nature, comprising about 800 square miles, and on a scale of l inch to l mile.
Figure 1—Key map showing the location of the map-area.
The bedrock is of Precambrian age, and consists of metavolcanics, metasediments, basic intrusive rocks, granitic rocks, and diabase dikes.
The major feature of the area is the Dayohessarah Lake metavolcanic- metasedimentary belt, which is between one and 3*^ miles wide and ap proximately 24 miles long. The major rock units of the belt trend north westerly through the south and central portions of the area, and swing northeasterly north of Hambleton Lake. The belt is enclosed and intruded by younger granite and granite gneiss. Basic intrusive rocks intrude the metavolcanics and metasediments.
No mineral deposits of economic importance were found.
Geology of the
Dayohessarah Lake Area
District of Algoma
By K. G. Fenwick1
INTRODUCTION
During the field seasons of 1963 and 1964, a reconnaissance geological survey of the Dayohessarah Lake area in the District of Algoma was made by the author. The map-area lies between north latitudes 48032' and 49003' and west longitudes 84047' and 85020' (Algoma District boundary); this covers about 800 square miles. Dayohessarah Lake is approximately in the centre of the area, which lies in the Sault Ste. Marie Mining Division.
Geological mapping was done by means of pace-and-compass traverses, checked by reference to vertical aerial photographs. Traverses were run 80 chains apart except where the geological complexities required more detailed mapping; in such cases, traverses were spaced at intervals of 20 to 40 chains.
Basemaps at scales of l inch to J^ mile and l inch to ^ mile were supplied by the Cartographic Unit of the Ontario Department of Mines. The aerial photographs were obtained from the Ontario Department of Lands and Forests (Silviculture Section, Timber Branch) and, in the general interpretation of the area, were used in conjunction with O.D.M.-G.S.C. aeromagnetic maps Nos. 2180G, 2196G, 2179G, 2195G, 2178G, and 2194G.
The geological map, No. 2129 (back pocket) is on a scale of l inch to 2 miles, and represents a compilation of all geological work done by the author, parts of which have been published by the Ontario Department of Mines in 1964 as preliminary geological maps Nos. P.226, P.227, and P.228.
Acknowledgments. During the field work, able assistance was given by the following university graduates and undergraduate students: P. F. Joseph, W. A. Kilfoyle, J. R. Bennett, and S. Griffith in 1963; G. D. Watts, N. H. Black, W. O. Seller, M. French, P. Kear, and J. Strombom in 1964. Messrs. Joseph, Watts, and Black, as senior assistants, were engaged in independent mapping during their employment.
1 Dept. of Geology, Queen's University, Kingston, Ontario, 1964-65. Manuscript received by the Chief Geologist 27 May 1965.
Dayohessarah Lake area
Thanks are extended to the members of the Ontario Department of Lands and Forests at White River, for their hospitality and co-operation, and for valuable information concerning the area; and to Mr. Robert Nyman, pilot for White River Air Services Limited, for many courtesies to the party during the season.
Grateful acknowledgment is made to Dr. P. E. Giblin, resident geologist at Sault Ste. Marie, who visited and gave advice on the area during the 1963 season; and to Dr. A. W. Jolliffe, professor at Queen's University, who aided the author in the preparation of this report.
Thanks are also due the Abitibi Power and Paper Company Limited for permitting the field party, in 1963 and 1964, to use their timber-roads for access to the area.
Means of Access. The town of White River, in the southwest corner of the Dayohessarah Lake map-area, is on Highway 17, about 200 miles northwest of Sault Ste. Marie, and 240 miles east of Port Arthur. The Canadian Pacific Railway line passes through the town. The townships of Common, Hunt, and Township 66 are accessible from Highway 17.
The northwestern part of the map-area can be reached by car from Regan, on Highway 17, north along the timber-roads of the Abitibi Power and Paper Company Limited, but special permission from the company is needed before using this road.
The remainder of the area is most conveniently reached by air. Tukanee Lake, 4 miles north of the town of White River, serves as the airbase for White River Air Services Limited and for the Ontario Department of Lands and Forests.
Previous Geological Work. A report by Arthur L. Parsons in 1907 is the earliest reference to the geology of the area (Parsons 1908). He was attached to an Ontario Bureau of Mines geological party and mapped along the boundary between the Thunder Bay and Algoma districts.
In 1928, J. E. Maynard mapped the Oba area for the Ontario Department of Mines (Maynard 1929), This lies immediately east of the Dayohessarah map- area.
In 1957 and 1958, the Canadian Pacific Railway Company made recon naissance geological studies of the Dayohessarah Lake metavolcanic-meta- sedimentary belt, the Kwinkwaga Lake area at the western side of the map-area, and the Kabinakagami Lake area, which includes the eastern side of the area.
In 1963, some prospecting was done in the area by Noranda Mines Limited, and in 1964, Falconbridge Nickel Mines Limited staked 230 claims in the town ships of Drew and Cholette, directly north of the map-area.
In 1963, the Ontario Department of Mines and the Geological Survey of Canada jointly published aeromagnetic maps of this region.
Topography and Drainage. The major part of the map-area lies immediately south and west of the divide between James Bay and Lake Superior. This height of land passes east of Tocheri Lake, east of the Shabotik River, and east of Gourlay and Strickland lakes. The majority of the lakes in the area drain into either the Shabotik River or the White River, which are the main waterways and which flow westward into White Lake, and from there to Lake Superior.
The elevation is about 1,500 feet above mean sea-level in the southern two-thirds of the area. Prominent pegmatite ridges are higher, and one of these
ridges west of Wawigami Lake rises to an elevation of 1,845 feet above sea-level. The northern part of the area is low and is about 1,300 feet above sea-level; numerous swamps and muskegs are present in this area. The above elevations are taken from Canada Dept. of National Defence Aeronautical Chart, Geraldton- White River N.W.48/88.
Small sand plains are common in the area and are characterized by small straight pines and spruce, and by a lack of underbrush. Eskers are abundant and, in some cases, rise to more than 50 feet above the general level, and are up to six miles in length. These eskers generally trend southwest, and are sinuous. They frequently form traps enclosing elongate lakes. The sand plains and eskers are in the low areas. Undrained kettle lakes are also found here.
Another strong topographic feature are the arcuate shorelines of bays on the east sides of many lakes in the area; Matthews, Gourlay, and Wawigami lakes have good examples of this. This suggests that the prominent wind direction is from the west and southwest.Amount and Distribution of Outcrop. Bedrock is exposed in most of the area. The granite and pegmatites that occur in the southern part of the area form marked ridges, and rock exposures are abundant. Some of the lakes in this area are completely rimmed by rock.
The area underlain by metavolcanics and metasediments is topographically lower, shows less variation in relief, and has fewer outcrops. In this region, glacial deposits of esker and morainal character are the most pronounced topographic features.
Many erratics were seen throughout the area and boulders thirty feet high were found south of Beaton Lake in Gourlay township.
NATURAL RESOURCESForests and Lumbering. Trees found in this region are black and white spruce, balsam, poplar, tamarack, pine, cedar, white birch, and balm of gilead. In the sandy regions, open stands of jackpine are common. Scrub alders grow in the swamps and along creek banks.
The cutting concession in the area is owned by the Abitibi Power and Paper Company Limited, which has a large camp at Cupa Lake in Magone township. Timber has been cut in Welsh, Matthews, Hambleton, and Magone townships, and slash is abundant. Forest fires in the region have occurred in the last ten years, but have not been extensive.
Fish and game. The White River area is well known to sportsmen. Moose, bear, and grouse are all to be found here and the hunting is generally regarded as being good. Few deer are present in the district, and it is not practical to hunt for these animals. Occasionally beaver, fox, and otter are trapped during the winter months. In the White River area, northern pike and pickerel (walleye) are found together in many lakes. Tukanee and Dayohessarah lakes afford excellent angling for lake trout.
Tourism. The tourist business has probably provided the greatest revenue for the area in recent years. Chartered flights can be made with considerable ease to most parts of the area during the summer and fall months. The great natural beauty of the country, the abundance of fish and game, and its easy accessibility to tourists from midwestern United States, makes this part of Ontario particularly attractive to lovers of the outdoors.
Dayohessarah Lake area
GENERAL GEOLOGY
All the bedrock in the map-area is of Precambrian age. Dayohessarah Lake is underlain by metavolcanics and metasediments that form a narrow belt between l and 3J^ miles wide, and approximately 24 miles long. The centre of this belt was mapped during the 1963 field season (Ontario Department of Mines preliminary geological maps Nos. P.226, P.227, and P.228) and the north and south extension of it was mapped in 1964. Both the north and south ends of the belt disappear into lowlands. The geological succession is given in the Table of Formations.
Rocks of the metavolcanic-rnetasedimentary belt appear to be the oldest in the map-area and consist of sedimentary schists, gneisses, and conglomerates, that are flanked on the east and west by volcanic flows and tuffs. In general, the metasediments have undergone deeper erosion, leaving a trough-like depression that is in part occupied by Dayohessarah Lake and the morainal debris in the southern section of the area. The profuse interbedding and gradation of volcanic
TABLE OF FORMATIONS
CENOZOIC
RECENT Swamp and stream deposits. PLEISTOCENE Sand, gravel, clay.
Unconformity PRECAMBRIAN
PROTEROZOIC
KEWEENAWANDiabase, porphyritic diabase.
Intrusive Contact
ARCHEANGRANITIC ROCKS
Biotite granite; hornblende granite; feldspar porphyry; biotite granite gneiss; pegmatite; aplite; migmatite; hornblende granite gneiss.
Intrusive Contact
BASIC INTRUSIVE ROCKSGabbro; olivine gabbro; metagabbro; metagabbro porphyry.
Intrusive Contact
METASEDIMENTS AND METAVOLCANICS
Metavolcanics:Amphibolite; amphibolite schist; basic to intermediate lava; agglomerate;dioritic, gabbroic lava; tuff, basic sedimentary rocks; rhyolite.
Metasediments:Quartz-plagioclase-biotite schist; garnetiferous biotite schist; pebble con
glomerate.
rocks to tuff and to sedimentary rocks, along the west contact of the meta- sediments and the metavolcanics, would suggest that they were deposited at about the same time.
This metavolcanic-metasedimentary belt probably represents a remnant of a more extensive series. The belt at one time could have been connected to the small volcanic belt in Larkin township northeast of the map-area.
In general, the contact-area between the metavolcanics and the enclosing granitic rocks is marked by a pronounced escarpment; the granitic rocks occupy the lower ground. Except for a few inclusions and rafts of metavolcanics, the area west of the belt is entirely granite gneiss.
The metavolcanics and metasediments are intruded by sills, dikes, and small stocks of granitic material, and a migmatite complex is found along the west shore of Dayohessarah Lake.
Granite gneiss, hornblende gneiss, pegmatite, and massive pink granite are the principal igneous rocks outside the boundaries of the Dayohessarah Lake metavolcanic-metasedimentary belt. Pegmatites are very prominent in the southern part of the map-area and are seen as high ridges and cliffs. Assumed contacts have been drawn between the gneisses and the massive granites.
The granitic rock appears to be younger than the minor intrusions of gabbro and metagabbro, which occur as dikes and small plutons in both the metavolcanics and the metasediments around the north end of Dayohessarah Lake. These basic intrusions are highly altered and display a brownish weathered surface.
The youngest rocks are diabase dikes, and these intrude all other rock units. Their width ranges between a few inches and two hundred feet.
Potassium-argon dating from nearby areas suggests that the regional meta morphism occurred about 2,480 million years ago, and that the diabase dikes may be about 1,120 million years old. The age determinations were made in biotite (Leechetal 1963) (Stockwell and Williams 1964) and are given in Table 1.
Table lAge determinations in biotite (after Leechetal 1963; and after Stockwell and Williams 1964}.
ROCK TYPE K-AR AGE LOCATION OF SAMPLE
Biotite paraschist
Biotite paraschistDiabase
millionsof years
2,465
2,5001,120
Roadcut 3 miles northeast of Manitouwadge,12 miles northwest of map-area.Highway 17, 35 miles south of map-area.Highway 17, 23 miles south of map-area.
Pleistocene deposits of till, sand, and gravel form a thick mantle over much of the northwestern part of the area. Eskers and sand beaches are common. Numerous sporadic areas of muskeg cover the northern and northeastern parts of the area.
Dayohessarah Lake area
Metavolcanics
The metavolcanic rocks of the area are found chiefly in the metavolcanic- metasedimentary belt that underlies Dayohessarah Lake. They are also repre sented in many small amphibolitic lenticular masses in the surrounding granitic rocks.
The metavolcanics of this belt consist chiefly of amphibolite (both massive and schistose), basic to intermediate lava, and volcanic fragmental types such as tuff and agglomerate. In the vicinity of Dayohessarah Lake, and to the south of it, the rocks can be divided into two general types. Those of the eastern flank are mainly basic flows containing a few horizons of interbanded basic tuffs. The western belt is predominantly a series of interbanded tuffs and flows of inter mediate composition.
Along the northwest contact of the metasediments and the metavolcanics, an arbitrary boundary has been drawn because the metasediments and the bedded tuffs, on opposite sides of the contact, grade into each other. In many cases, these two rock types are grouped together (See "2f" on Map 2129).
Tuffaceous members in the western band and especially the northern end of the belt are fine-grained platy rocks that are dark-grey to black, and that weather to various shades of brown and black. They are composed of minute crystals of hornblende (60 to 80 percent) in parallel orientation, together with finely granular quartz and feldspar. Segregation of the light and dark minerals creates the finely-banded appearance. This tuffaceous volcanic rock has been changed to a fine-textured amphibolite schist by intense metamorphism.
The basic lava flows in general are andesitic and massive. They weather from dirty-green to brown, and are normally black on a fresh surface. The flows have the same general appearance as the tuffs but lack the fine banding and are less apt to be schistose.
Rhyolites are rare in this group, and only one narrow band has been recog nized. This is on the east boundary of Strickland township, and probably rep resents the southwest extension of the large metavolcanic belt in Nameigos township, which lies east. The rhyolite is fine-grained and greenish.
On the north shore of Dayohessarah Lake, an outcrop of fine-grained basic metavolcanic with garnet porphyroblasts up to 5 mm. wide was found. The garnets stand in relief above the rock surface. This is the only place where the author found garnets associated with the metavolcanics.
Coarse-grained basic flow rocks are found throughout the belt and also in some of the remnant bands in the granitic gneiss. They have a metamorphic texture and exhibit hornblende metacrysts, up to ^ inch across. They are best described as medium-grained to coarse-grained amphibolites of probable volcanic origin.
The metavolcanics and metasediments are intruded by sills, dikes, and small stocks of granitic material. Photo l shows metavolcanic rock cut by pegmatites and quartz stringers.
Lit par lit injection gneiss and migmatite contact phases are common along the metasedimentary-metavolcanic rock contacts and also along the metavolcanic- granitic rock contacts.
ODM 7670 Photo 1-Metavolcanic rock cut by pegmatites and quartz stringers; Dayohessarah Lake.
M eta sediments
The metasediments in the map-area are confined to the central section of the Dayohessarah metavolcanic-metasedimentary belt. Because of the relative softness of these rocks, erosion has cut deep except where they were protected by the harder, more resistant volcanic rocks.
The metasediments include quartz-plagioclase-biotite schists and gneisses, garnetiferous biotite schists, and conglomerate. The quartz-plagioclase-biotite schists and gneisses are the most abundant of these, and are found throughout the area. Fresh surfaces are grey, and weathered surfaces are dark-greyish-brown. In thin section, the rock is composed of quartz (50 percent), biotite (40 percent), and albite-oligoclase (10 percent) with traces of garnet, white mica, epidote, and chlorite. The rock appears to have originated from a fine-grained impure sand stone.
The garnetiferous biotite schist is also widespread, but occurs only as narrow beds that are seldom more than a few feet thick. In these beds the garnets, which are up to ^ inch across, tend to be uniformly distributed and form 10 percent of the rock. Weathering has removed much of the matrix of the fine-grained
Dayohessarah Lake area
Photo 2—Garnetiferous biotite schist, island in Dayohessarah Lake.ODM 7671
schist, leaving the garnets protruding above the rock surface. Attempts to deter mine tops from garnet concentration failed because the quantity of garnets seemed to grade in both directions across the bedding. Photo 2 shows these garnetiferous beds.
The conglomerate occurs on the long curved point and chain of islands at the head of Dayohessarah Lake. It has been intensely sheared and contains deformed quartzite pebbles that are up to 6 inches in length and ^ inch in width. The matrix of the conglomerate is composed of quartz and biotite. The chain of islands mentioned above has been well weathered and many of the quartzite cobbles have been lost on the weathered surfaces due to the removal of the soft matrix by wave action.
The true width of the conglomerate cannot be determined because a large portion lies under the waters of Dayohessarah Lake. No conglomerates were found along the south portion of the lake.
The metasedimentary rocks, especially on the west shore of Dayohessarah Lake have been injected by varying amounts of pegmatitic and granitic material. Some of the quartz and feldspar are segregated parallel to the foliation. This migmatite (lit par lit injection gneiss) is commonly developed along the contact between the sedimentary and volcanic rocks. In order to retain on Map 2129 the original shape of the sedimentary belt, the author mapped the migmatite complex on the west shore of Dayohessarah Lake as "la, 4". ("la" represents quartz- plagioclase-biotite schist, "4" represents granitic rock).
8
Photo 3-Sqoeezed conglomerate, island in Dayohessarah Lake.
DU . A i i L . ODM 7673 Photo 4-1 n ten se shearing in metasediment*; Dayohessarah Lake.
9
Dayohessarah Lake area
Unaltered sedimentary rocks are very uncommon. These rocks have been subjected to intense metamorphism and exhibit banding and shearing that strike in the general trend of the belt. The rocks have very steep dips. Photo 4 (on page 9) shows intense shearing.
Basic Intrusive Rocks
Gabbro and metagabbro occur as dikes and small plutons in both the meta- volcanics and the metasediments around the north end of Dayohessarah Lake. These basic intrusions are of uncertain age but are believed to be pre-granite.
The rock is dark-green on the fresh surface and displays a typical brownish weathered surface. Although it has been highly altered, the massive structure and original medium-grained texture can be observed. It is possible that it is a basic intrusive rock of the same age as the volcanic rocks. Pyrite and magnetite are disseminated throughout the rock.
Granitic Rocks
The principal igneous rocks outside the boundaries of the Dayohessarah Lake metavolcanic-metasedimentary belt are massive pink granite, granitic gneiss and pegmatites.
The granite pegmatites are found as large dike-sheets and as smaller dikes and irregular pegmatite masses, cutting all rock types in the area except diabase. The large granite pegmatite dike-sheets are intruded over a large area in the southern part of the map-area. Much of the rock exposure in this area is pegma tite capping and it was difficult to determine the shapes of these units or to establish their relations with the underlying formations.
The pegmatite is composed of coarse-grained crystals of orthoclase and quartz with a small amount of biotite and magnetite. Photo 5 shows a type sample of coarse-grained pegmatite with orthoclase crystals from l inch to 1^ inches across.
Commonly these large pegmatite units are composed of an irregular mixture of fine-grained aplitic material and medium-grained to coarse-grained pegmatitic material.
Usually the smaller pegmatite dikes show a uniform grain size across their full width, but, in a few instances, the pegmatites are finer-grained at the contacts and become coarser inward. They range from less than l foot to 10 feet in width. Inclusions of the country rock are not uncommon.
Three major groups of granitic rocks are found within the map-area and are separated by assumed contacts. These groups are: pink massive granite; grey biotite granite gneiss; and, pink hornblende granite gneiss. The latter two are cut by pegmatitic, aplitic, and migmatitic material. Lack of field evidence
10
Photo 5-Coarse-grained pegmatite.ODM 7674
precluded age differentiation, but it is suspected that two or three ages of granitic intrusion occurred in this area.
Massive pink granite underlies the northeast corner and the southern part of the map-area. The granite in the northeast corner is homogeneous and, throughout most of this area, the only other rock type found is younger diabase. This granite becomes gneissic near its boundary with the metavolcanic-meta- sedimentary belt. In the southern part of the area, the granite is also homogeneous but occurs with many other rock types. In the southeast corner, this granite grades into feldspar porphyry along the contact between the granite gneiss and the granite. A thin section of this granite shows orthoclase (48 percent), quartz (48 percent) and plagioclase, biotite, and magnetite (4 percent). The orthoclase has been kaolinized and contains inclusions of hematite, which accounts for its pink colour. Both types are medium-grained to fine-grained, massive, and leucocratic. The granite weathers reddish to white.
Light-grey banded biotite granite gneiss is the most abundant rock in the map-area and encloses most of the metavolcanic-metasedimentary belt. These rocks are medium-grained and well foliated, and are composed of quartz (15 percent), orthoclase (45 percent), plagioclase (15 percent), and biotite (25 percent). Epidote lines many seams in the granite rocks.
Pink hornblende granite gneiss is found in the vicinity of Danny Lake. These rocks are composed of hornblende (50 percent), quartz (10 percent), orthoclase (40 percent), and traces of chlorite, pyrite, and magnetite. The rock weathers pink to white and is medium-grained to coarse-grained.
11
Dayohessarah Lake area
Photo 6—Breccia-type migmatite.ODM 7675
Migmatites are found throughout the western and southern parts of the map-area, and are composed of highly altered remnants of pre-existing volcanic and sedimentary rocks mixed thoroughly with variable amounts of granitic material. Two types of migmatites occur: a breccia type, in which fragments of the older rocks are cemented by dikes and veins of granitic rock; a banded type, in which layers of the older material alternate with layers of granitic material (lit par lit structure).
Keweenawan
The youngest rocks are diabase dikes, and these intrude all other rock types in the area. Their width ranges between a few inches and 200 feet. The usual rock found in the dikes is medium-grained to coarse-grained, with lath-shaped feldspar showing the typical diabasic texture. In thin section, the rock is found to consist of labradorite, pyroxene, and minor amounts of quartz, magnetite, pyrite, and biotite with secondary calcite and chlorite. The diabase is brownish on weathered surfaces and dark-grey on fresh surfaces. Occasional porphyritic phases show grey to yellow plagioclase phenocrysts, up to an inch across, set in a dark-grey medium-grained groundmass of plagioclase and pyroxene.
All the dikes cut cleanly across the intruded rocks and display chilled contacts. They trend predominantly either northeast or northwest and dip vertically.
12
Pleistocene and Recent
Pleistocene deposits of sand, gravel, and erratic boulders are found through out the area. The Pleistocene mantle, in general, is thin with the exception of the area around Gourlay Lake, Kakakiwibik Lake, and the northwest portion of the map-area. Glacial striae indicate that the direction of the ice movement was between S150W and S300W. Striae are not common. Some of the outcrops of rock, especially the pegmatite ridges, have typical roches moutonnees forms with gently sloping stoss sides and steeper lee sides. Glacial fluting is prominent in Cooper township.
The eskers show a general parallelism to glacial striae and are common in the northeast corner of the map-area. They are composed of sand and gravel. The largest esker traced on an aerial photograph of the area is about six miles long.
The Abitibi Power and Paper Company Limited was able to use the abundant sand and gravel deposits in the northwest portion of the area to construct their lumber roads.
STRUCTURAL GEOLOGY
The major rock units of the belt trend northwesterly through the south and central parts of the area, and swing northeasterly in the area north of Hambleton Lake. The schistosity in the metavolcanics and metasediments is very pro nounced, and follows these trends. The gneissosity of the granite gneiss (that is, within two miles of the belt) also follows these trends.
The metasediments are considered by the author to be younger than the volcanic rocks, although there is no definite field evidence to substantiate this statement. The two rocks were not found with a distinct contact. Primary features are not present or apparent and have probably been obliterated by the extreme shearing and metamorphism. The metasediments and metavolcanics may follow the axis of a synclinal fold; however, as mentioned earlier, the lack of top determinations in the area prevents the possibility of proving this.
A number of prominent topographic lineaments were plotted from the aerial photographs. They were found to parallel the two sets of diabase dikes in the map-area, which strike either northeast or northwest. It can be assumed that these linears are valleys that are formed either from weathered diabase dikes or from vertical joints.
ECONOMIC GEOLOGY
Unmineralized quartz veins are common in the metavolcanics. Pyrite and magnetite are disseminated throughout the metavolcanics and in the diabase and basic intrusive dikes.
T. W. Page, in the Canadian Pacific Railway Company's report on this area, (Page 1958) states that he was able to obtain a positive test for nickel on samples of basic intrusive rocks from the north end of Dayohessarah Lake. Dimethylgly- oxime was used as the reagent. Mr. Page did not attach any significance to this.
Large sand and gravel deposits occur in the area and some have been used in the construction of Highway 17 and the timber roads of the Abitibi Power and Paper Company Limited.
A minor showing of molybdenite was noted in an outcrop of basic intrusive rock in Strickland township.
13
Dayohessarah Lake area
Minor sulphide mineralization is found in the map-area in the metavolcanics and granites.
Three prominent aeromagnetic anomalies lie in the map-area. One, along the north shore of Dayohessarah Lake, has been caused by metagabbro intrusions. Another anomaly, west of Hambleton Lake, occurs near two diabase dikes; the trend of the dikes is not parallel to that of the anomaly, which could therefore result from a subsurface feature. The third anomaly is south of Fido Lake in Johns township and is caused by magnetite in a raft of metavolcanics. The Ontario Department of Mines Laboratory Branch reports 8.10 percent soluble iron in a specimen of this rock. This amount is too small to be of economic importance.
TextsBartley, M. W.
1958a: A report on prospecting in the Kabinakagami Lake area; Canadian Pacific Railway Company, Department of Industrial Development. (Reference copy available at Ontario Dept. Mines Library in Toronto.)
1958b: Exploration report; Canadian Pacific Railway Company, Department of Industrial Development. (Reference copy available at Ontario Dept. Mines Library in Toronto.)
Leech, G. B.; Lowdon, J. A.; Stockwell, C. H.; and Wanless, R. K.1963: Age determinations and geological studies; Geol. Surv. Canada, Paper 63-17.
Maynard, J. E.1929: Oba area; Ontario Dept. Mines, Vol. 38, pt. 6, p. 114-125. (published 1930).
Milne, V. G.1964: Geology of the Flanders Lake area; Ontario Dept. Mines, Geological Report No. 21.
Page, T. W.1958: Geology of the Dayohessarah Lake area; a report to the Department of Industrial
Development of the Canadian Pacific Railway Company. (Reference copy available at Ontario Dept. Mines Library in Toronto.)
Parsons, Arthur L.1908: Geology of Thunder Bay-Algoma boundary; Ontario Bur. (now Dept.) Mines, Vol. 17,
p. 95-135. Pye, E. G.
1962: Geology and scenery along the north shore of Lake Superior, Ontario Dept. Mines,Geological Circular No. 10, p. 48-50.
Stockwell, C. H., and Williams, H.1964: Age determinations and geological studies; Geol. Surv. Canada, Paper 64-17, pt. 2.
MapsO.D.M.-G.S.C.
Maps 2178G, 2179G, 2180G. Aeromagnetic Series; scale l inch to l mile. Ontario Dept.Mines-Geol. Surv. Canada; published 1962.
Maps 2194G, 2195G, 2196G. Aeromagnetic Series; scale l inch to l mile. Ontario Dept. Mines-Geol. Surv. Canada; published 1963.
14
Index
PAGEAbitibi Power and Paper Co. Ltd...........2,13Access. . ... . .. ... . ... . . .. ... . .. . .. . . . .. . . . . 2Acknowledgments. . . . . . . . . . . . . . . . . . . . . .. . . . . lAge determinations. See Dating.Agglomerate. . . .. . . .. . .. . .. . . .. . .. . . . . . .. . . .6Amphibolite. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Anomalies, aeromagnetic. . . . . . . . . . . . . . . . . . . . 14Archean rocks..... . . . . . . . ................6-12
Banding:In metasediments. . . . . . . . . .. . . . . . . . . . . . . . 10In migmatites.... . . . . . . .. . . .. . . .. . . . . . . . . 12In tuffs. . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Beaton Lake... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Bennett, J. R.. . . . . . . .. . . . . . . .. . . . . . . . . . . . . . lBiotite, age determinations in.. . . . . . . . . . . . . . . .5Biotite granite gneiss. . . .. . . .. . . . . . . . . . . . 10, 11Biotite schist. . .. . . . . . . . . .. . . . . . . . . . . . . . . .. . 7
Age determination of......................5Garnetiferous, photo.. . . . . .. . . . . . . . . . . .. . .. 8
Black, N. H.................................1
Common township..... . . . . . . . . . . . . . . . . . . . . . . 2Conglomerate, notes and photo..... . . . . . . .. . 7-9Cooper township. . . . . . . . . . . . . . . . . . .. . . . . . . . 13
Danny Lake,rocks.........................11Dating, potassium-argon. . . . .. . . . . . . . . . . . . . . . 5Dayohessarah Lake:
Aeromagnetic anomaly.. . . . . . . . . . . . . . . . . . . 14Rocks, notes and photos..... . . . . . . . . . . . .5-10
nickel in..... . . . . . . . . . . . . .. . . .. . . . . . ... 13Diabase. .. . . . . . . . . .. . . . . . .. . .. . ...........12
Age determination of. . . . . . . . . . . . . . . . . . . . . . 5Drainage... .. . . . . . .. . . . . . .. . . . . . . . . . . . . . . . .2
Economic geology. .. . . . . . . . . .. . . . . . . . . . . 13, 14Escarpment..... . . . . .. . . .. . . . . . . . . . . . . . . . . . .5Eskers. .. . . . . .. . . .. . . . . . .. . . . . . . . . . .. . . . 3, 13
Falconbridge Nickel Mines Ltd... . . . . . . . . . . . . . 2Feldspar porphyry.........................11Fido Lake, aeromagnetic anomaly. . . . . . . . . . . . 14Fish and game. See Natural resources.Fluting, glacial... . . . . . . . . . . . . . . . . . . . . . . . . . . 13Forests. See Natural resources.Formations, table of.. . . . . . . . . . . . . . . . . . . . . . .. 4French, M.. ... . .. . . . . . . . . . . . . . . . . . . . . . . . .. l
Gabbro................................ . . . 10Garnetiferous rocks, notes and photo..... . . . . 6-8Geology, general. . . . . . . . . . . . . . . . . . . . . . . . .4-13Geology, structural. . . . . . . . . . . . . . . . . . . . . . . .. 13Glacial deposits... . . . . . . . . . . . . . . . . . . . . .3, 5, 13
PAGEGneiss. See Granite gneiss.Gourlay Lake.... .... ... . .... ....... .... . . ..3
Glacial deposits. . . ... . .. . . . .. . .. . . .. . . ... 13Gourlay township. . . . .. . . . . . . . . . . .. . . .. . . .. . 3Granite.. . .. . . . . . . . . . . . . . . . .. . . . . .. . . . . 10, 11Granite gneiss. . . . .. . . .. . . . . . . .. . .. .. . .. . .. 10
See also: Biotite granite gneiss.Hornblende granite gneiss.
Granitic rocks..... . . . . .. . . . .. . .. . . .. . . . . 10-12Gravel deposits. . . ... . .. . . ... . . ... . .. . . ... . 13Griffith, S..... . . .. . . .. . . .. . . .. . . .. . . . . . . . . . . l
Hambleton Lake. . . . . . . . . . .. . . . . . . .. . . . . . . . 13Aeromagnetic anomaly.. . . . . . . . . . . . . . . ... . 14
Hornblende granite gneiss. . . . . . . . . . . . . . . . 10, 11Hunt township... . . .. . . . . . . . . . . . . . . . . . . . .. . . 2
Injection gneiss. . . ... . . . . . . . . . . . . . . . . . . . . . 6, 8See also Migmatite.
Intrusive rocks... . ........ . .. . . . . . . . . . . .10-12Iron. See Magnetite.
Johns township, aeromagnetic anomaly..... . . . 14 olliffe, A. W.... . . . . . . . . . . . . .. . . . . . . . . . . . . . . 2 oseph, P. F.... . . .. ....................... . l
Kakakiwibik Lake, glacial deposits.... .. . . . . . 13Rear, P.....................................lKettle lakes. . . . . .. . . . . . . . . . . .. . . .. . . . . . . . . .3Keweenawan diabase. . . . . . . . . . . . . . . . . . . . . . . 12Kilfoyle, W. A...... . . . . . . . . . . . . . . . . . . . . . . . . . l
Larkin township..... . . . . . . . . . . . . . . . . . . . . . . . . 5Lava, basic. . ... .. . . . . . . . . . . . . . . . . . . . . . . . . . . 6Lineaments, topographic. . . . . . . . .. . . . . . . . . . . 13
Magnetite..... . . .. . . .. . . . . . . . . . . .. . . 10, 13, 14Map, geological, coloured. . . . . . . . . . . .back pocketMapping methods. . . .. . . . . . . . . . .. . . .. . . . . . . . lMatthews Lake. . . . . . . . . . . . . .. . . . . . . . . . . . . . . 3Metagabbro. . . ... . . .. . . .. . . . . . . . . . . . . . . . .. 10Metasediments, lithology and photos..... . . . 7-10Metavolcanics, lithology and photo. . . ... ...6, 7
Magnetite in..... . . . . . . . . . . . . . . . . . . . .. . . . 14Migmatite. . . . . . . . . . .. . . . . . . . . . . . . . . . .6, 8, 12
Breccia-type, photo... . . . . . . . . . . . . . . . . . . . . 12Molybdenite... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Nameigos township.. . . . . . . . . . . . . . . . . . . . . . . . .6Natural resources..... . . . . . . . . . . . . . . . . . . . . . . . 3Nickel. . ................. ... ..... . . . ......13Noranda Mines Ltd.... .... . . ... . .. .......... 2
Outcrop distribution. . .3
15
Dayohessarah Lake area
PAGEPage, T. W.............................13, 14Pegmatite. . .. . . .. . . . . .. . . . . . . .. . . . . .. . . . . . 10
Photos.... . .... ........ . ... . . . . . . .. .. .7, 11Topographic expression of... ... . . . . .... . . 2, 3
Porphyritic diabase.. . . ...... ...... ...... . . . 12Prospecting activity. . ... . . . .. . . . . . . .. . . . . .. . 2Proterozoic rocks.. . . . . . . . . . . . . . . . . . . . . . . . . . 12Pyrite. . .. . .... . ..... ..... . ..... . ..... .10, 13
Quartz veins.. ... . . ... . . .. . . . . .. . . . . .... . . . 13Photo... . . . . . . . . . . . . . .. .. . . .. . . . . ... . . . ..7
Quartzite... . . . . . . .. . . . . ... . . . .. . . . . .. . . . . .. 8
Recent deposits. . . . . . . . ... . . . ... . . . ... . . . . . 13References, selected.... ...... ..... . ..... . ... 14Regan. . . . . .. . . . ... . ... . .. . ................2Rhyolite. . . ... . . .. . . . ... . . . .... ... .. . . . . .. . 6Roches moutonnees . . .. . . ....................13
Sand deposits. . . . . . . . . .. . . . . .. . . . . .. . . . ... . 13Plains............... . . .. . .... . . . . . . . . ... .3
PAGESeller, W. O................................. lShabotik River. .... . .. . . .. . . .. . . . . . . . . . . . . . .2Shearing in metasediments, photo. . . . . ... . . . . .9Strickland township. . . . . . . ... . .. . . . . .. . . . . . 13
Rocks.... . . ..... . . ... . . .. . . .... . .... . .. .. 6Strombom, J.. . .... .... . . . .. . . . . .. . . ... . .. . . lStructural geology.. .... . . . .... . . . ... . ... . . . 13Sulphides...... . . .. . . . . .. . . . . .. . . . . .. . . . 13, 14Surveys, geological ........................1,2
Topography. . .. . . . . ................. . . . . . . . 2Tourism. See Natural resources.Township 66..... ....... . . ..... . . . .. . . .. . . . . 2Tuff. ... .. .... . . . .... . . .... . . .... . . . . ... . . .6Tukanee Lake. . . . . ..... . ... . . . . . ... . . ... . . . 2
Veins. See Quartz veins.
Watts, G. D.. . . ...... ... .... . .. . . . ... . . . . .. lWawigami Lake..... ... ..... . ... . . . . .. . .. . . . 3White River. . . ... . . . . . . . . . . . ... . . . . ... . . . . .2
16
ONTARIO DEPARTMENT OF MINES
HON. G. C. WARDROPE, Minister of Mines D. P. Dougluss, Deputy Minister J. E. Thomson, Director, Geolof/icnl Branch
Map 2129
DAYOHESSARAH LAKE AREAALGOMA DISTRICT
Scale l: 126,720 or l Inch lo 2 Miles
Map 2129 Dayohessarah Lake Area
Scale l inch to 50 miles
N.T.S. reference 42C, 42F
LEGEND
CENOZOIC
RECENT Swamp and stream deposits.
PLEISTOCENE Sand, gravel, clay.
UNCONFORMITY
PRECAMBRIAN
PROTEROZOICKEWEENAWAN
5a Diabase.5b Porphyritic diabase.
INTRUSIVE CONTACT
4 Granitic rocks, undifferentiated.4a Biotite granite.41} Hornblende granite.4c Feldspar porphyry.4d Biotite granite gneiss.4e Pegmatite.4f Aplite.4g Migmatite.4h Hornblende granite gneiss,
INTRUSIVE CONTACT
BASIC INTRUSIVE ROCKS
3a Gabbro, olivine gabbro.3b Metagabbro, metagabbro porphyry.
INTRUSIVE CONTACT
METASEDIMENTS AND METAVOLCANICS*
METAVOLCANICS
2a Amphibolite, amphibolite schist. 2b Basic to intermediate lava. 2c Dioritic, gabbroic lava. 2d Tuff, basic sedimentary rocks. 2e Rhyolite.
METASEDIMENTS
1a Quartz-plagioclase-blotite schist. 1b Pebble conglomerate.
mag Magnetite.Mo Molybdenum.S Sulphide mineralization.
*The rocks of these groups are subdivided lithologi- cally and the order does not imply age relationship within the group, or between the groups.
.Mo
SYMBOLS
Glacial striae.
Esker.
Schistosity; (inclined, vertical).
Gneissosity; (inclined, vertical).
Geological boundary, position inter preted.
Lineament.
Jointing; (inclined, vertical).
Mineral occurrence.
Muskeg or swamp.
Motor road, Provincial highway number encircled where applicable.
Other road.
Trail, portage, winter road.
Township boundary, approximate loca tion only.
Township boundary, unsurveyed.
SOURCES OF INFORMATION
Geology by K. G. Fenwick and assistants, 1963, 1964.
Reports of Department of Industrial Development,Canadian Pacific Railway Company:T. W. Page, Geology of the Dayohessarah Lake Area,1958.M. W. Bartley, A report on prospecting in the Kabmak-agami Lake Area, 1958.M. W. Bartley, exploration report, 1958.
Cartography by B. Jackson and D. V. Impey, Ontario Department of Mines, 1966.
Base map derived from O.D.M. - G.S.C. aeromagnetic maps2178G, 2179G, 2180G, 2194G, 2195G, 2196G.
Magnetic declination in the area was 5" West, 1963.
