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Ontario Department of Mines Geological Branch
Open File Report 5001
Geology of the Black River Area
1967
ONTARIO DEPARTMENT OF MINES GEOLOGICAL BRANCH
OPEN FILE REPORT
No 5001
GEOLOGY OF THE
BLACK RIVER AREA
MARCH 1, 1©67
by V. G. Milne
v6',
GEOLOGICAL BRANCH ONTARIO PARLIAMENT BUILDINGS DEPARTMENT OF MINES TORONTO 2, ONTARIO
Open-file Reports Open-file reports are made available to the public subject to certain conditions. Anyone using them shall be deemed to have agreed to these conditions which are as follows: This report is unedited. Discrepancies may occur for which the Department does not assume liability. Open-file copies may be read at the following places: The Library (Room 1433, Whitney Block), Department of Mines, Parliament Buildings, Toronto. The office of the Resident Geologist in whose district the area covered by this report is located. A report cannot be taken out of these offices. Handwritten notes and sketches may be made from it. This particular report is on file in the Resident Geologist's office located at: 179 South Algoma St. , Port Arthur
pen-file reports cannot be handed out for office reading until a card, giving the name and address of the applicant, is filed with the Resident Geologist or Librarian. A copy of this report is available for inter- library loan. The Department cannot supply photocopies. Arrangements may be made for photocopying by an outside firm at the user's expense. The Librarian or Resident Geologist will supply information about these arrangements. The right to reproduce this report is reserved by the Ontario Department of Mines. Permis sion for other reproduction must be obtained in writing from the Director, Geological Branch. J. E. Thomson, Director, Geological Branch.
ONTARIO DEPARTMENT OF MINES
GEOLOGY OF THE BLACK RIVER AREA DISTRICT OF THUNDER BAY
by
V. G. Milne
Geological Report No. 5001
Project 64-7
Table of Contents
Abstract Introduction Prospecting and Mining Activity- Present Geological Survey Acknowledgments Previous Geological Work Topography Natural Resources General Geology Table of Formations Archean Mafic to Intermediate Metavolcanic Rocks Silicic to Intermediate Metavolcanic, Pyro and Metasedimentary Rocks Metasedimentary Rocks Mafic and Ultramafic Intrusive Rocks Metagabbro Serpentinized Peridotite Anorthositic Gneiss Mineralization Early Silicic Plutonic Rocks Late Silicic Plutonic Rocks Fourbay Lake Pluton Gowan Lake Pluton Bullring Lake Pluton Musher Lake Pluton Dotted Lake Batholith Silicic Dikes
-// -
Proterozoic Diabase Dikes 84 Pleistocene and Recent 88 Structural Geology 93 Folding 93 Faulting 100 Major Faults 101 Bullring Lake Fault 101 Phil Lake Fault 102 Pinegrove Lake Fault 102 Jenny Creek Fault 103 White Lake Fault 104 Other Faults 104 Economic Geology 107 Introduction 107 Stratigraphic Considerations in Mineral Exploration 108 Descriptions of Mineral Showings 111 Fairservice Occurrence(1) 111 Kusins Occurrence(2) 113 von Klein Occurrences(3) 115 Occurrence No. 1 116 Occurrence No. 2 116 Occurrence No. 3 117 Occurrence No. 4 118 Other Mineral Occurrences 120 Considerations in Future Exploration 122 Selected ZefccHCts /IS
-///-
FIGURES
No. 1 - A hypothetical structural cross-section on a north-
south line through the Black River and bordering areas
to the north and south, (page 99)
No. 2 - Plan of the pit locations and geological sketch map of
the Kusins lead-zinc showing, (page 113)
No. 3 - Surface geology and location of drill holes and electro
magnetic anomalies on the von Klein property based on
assessment work filed in 1962 by Mclntyre Porcupine Mines
Ltd., O.D.M. File No. 63-1210. (page 116) No. 4 - Geological plan in the location of electromagnetic
anomalous zone B (see Figure No. 3) with assay results
of trench samples. Based on assessment work filed in 1962
by Mclntyre Porcupine Mines Ltd., O.D.M. File No. 63-1210.
(page 118)
No. 5 - Geological plan in the location of electromagnetic
anomalous zone C (see Figure No. 3) with assay results
of trench samples. Based on assessment work filed in
1962 by Mclntyre Porcupine Mines Ltd., O.D.M. File No.
1210. (page 118)
"^ Illustrations are located at the rear of this report
ABSTRACT The map-area covers approximately 600 square miles bounded on the east by the Pic River Area (Ontario Department of Mines, 196 ), on the north by the Manitouwadge Area (Ontario Department of Mines, 1957) and extending as far east as White Lake. The report describes the geology, structure and mineral showings and briefly discusses regional structure on the basis of information from this area and from the adjoining areas noted above. The consolidated rocks are all of Precambrian age but much of the area is blanketed by thick deposits of glaciolacustrine and glaciofluvial gravel, sand and clay of Pleistocene age. Within the map-area a mafic metavolcanic formation, which includes pillowed units, has been interpreted as the oldest formation. The mafic metavolcanic rocks appear to form the lowermost horizon of a gradational sequence, younging throughAa thin formation of s'l/iti't mixed a-oi-4 to intermediate metavolcanic rocks, pyroclastic rocks and minor metasediments,.into a thick succession of metasediments consisting essentially of conglomerate and greywacke. These rocks have been intruded by metagabbro, serpentinite and granodiorite gneiss and folded about east-northeast and north-northwest trending axes. The extrusive and sedimentary rocks have been regionally metamorphosed to amphibolite facies and metamorphism and folding are believed to have developed at catazonal level cogenetically with the intrusion of the granodiorite gneiss which forms a domical mass of batholithic dimensions. Subsequently these rocks were intruded by large plutons, some of batholithic size, composed of hornblende-biotite and biotite granodiorite and
- Vttt - quartz monzonite. Finally all these formations were intruded by swarms of diabase dikes. Small showings of zinc and lead-zinc are present in the mafic metavolcanic rocks but of greater economic interest are 51 lie i e copper-nickel showings in the pyroclastic-acid- metavolcanic formation adjacent to the mafic metavolcanic unit. In the original copper-nickel showings in the area the mineralization occurs in isolated blocks of amphibolite rafted in pyroclastic S///V/C and areid extrusive rock units. Subsequent work has indicated mineralization in fracture and shear zones along the boundary of the mafic metavolcanic and pyroclastic formations and geophysical prospecting has outlined a number of extensive electromagnetic anomalies in the same zone. This area was under examination in 1966.
-/y
(Project 64-7)
Geology, of the Black River Area
by
V. G. Milne 1
Introduction There has been continued prospecting interest in the Manitouwadge area since the discovery of the Geco ore body in 1953 and more recently, much interest has been shown in copper, and copper-nickel prospects, in the Marathon area on the northeast shore of Lake Superior. A mapping project was started in 1963>and in that year the/Pic River area (Map Nos. 2098, 2099), north of Marathon, was completed. /v The Black River area adjoins the Pic River area on the east
and extends north to the Manitouwadge Area (Map No. 1957-8). A. The area covered in this report lies between latitudes 48°45T and 49°07T and longitudes 85°32» and 86°05» in the District of Thunder Bay. This represents about 600 square miles and includes parts of Grenville, Leslie, Gertrude and Cecil townships. The eastern limit of the area follows the west boundaries of Bryant, Atikameg and McGill townships and the west limit is marked by the east boundary of township 75 and corresponds to the east boundary of the Pic River Area Map Nos. 2098 and 2099- Ontario Highway No. 614 to Manitouwadge extends north-south through the centre of the area and the southern limit of the map is about 4 miles Geologist, Ontario Department of Mines, Toronto. Manuscript received by the Director, Geological Branch, 20th October 1966. north of the junction between this highway and Trans-Canada Highway, Highway No. 17. The northern limit of the area corresponds approximately to the southern limit of the
Manitouwadge AreaAMap No. 1957-8'.
Access to the area is very good. Much of the area is accessible from Highways No. 17 and No. 614, Ontario Paper
Company roads, Marathon Corporation roads .and old lumbering roads branching from Highway No. 614 to Theresa Lake, to
Dead Otter Lake, and to Amwri Lake and the Black River.
Log driving trails along the Black River and numerous over grown logging trails also facilitate access. The Canadian
Pacific Railway spur line, extending from the main line at
Struthers to Manitouwadge, also passes through the centre of the area. The least accessible parts of the area are in the west and northeast but these can be reached quite easily by float plane from White River about 40 miles east-southeast of the map-area.
Prospecting and Mining Activity
Since discovery of the ore bodies in the Manitouwadge area in 1953 the whole district generally has been regarded with interest. Claims have been staked and restaked at various times, mostly along a belt extending northeast from
Valley Lake to Dead Otter Lake. Extensive new staking was done in the spring of 1965 in the area north, south and west of Dotted and Dead Otter Lakes. In I965 most of the ground between Dotted Lake, Theresa Lake and the Black River was covered by staking,
In 1962 Mclntyre Porcupine Mines Ltd. surveyed and drilled
a 52 claim area enclosing the yon Klein (Location No. 3, see map) copper-nickel showing just east of Summers Lake on
Highway No. 614 (Assessment File No. 63- ^'P). I-u 196jj
auamo da illiii{j, waa dune by •M-i«4ag~^ in the area between Amwri, LflV^ nr>H +-h" BirxJi^iwEti %i:7;"l- ir mila Lu 1 iiillu uaot of tho 'ifivei1 (TiltrWU'.' 6J- "—-) "awd ^n late 1963 T. and W. Kusins uncovered a lead-zinc showing (Location No. 2, see map) between the Black River and Valley Lake, about 3/4 mile west of the river. The Kusins showing was examined in 1965 by the Consolidated Mining and Smelting Company of Canada Ltd. (M,M &»"''i£o ^V. (/LJj%(p) At the time of writing Caravelle Mines Ltd. holds a large block of more than 100 claims enclosing the Von Klein copper- nickel showing and extending from Theresa Lake in the east to Highway No. 614 on the west, south of Dead Otter Lake. Irish Copper Mines Ltd. holds claims north of Dotted Lake enclosing a zinc showing (Location No J^£, see map) staked by B. Fair.service. Both companies flew geophysical surveys during the summer of 1965 and follow up work is continuing. A number of claims are held by M. Grey on the south and east of the Caravelle Mines block of claims. Present Geological Survey The report area was mapped during the summer months of 1964 and 1965. About 150 square miles in the southwest quarter of the area were mapped in I964 with the assistance of M.E. Coates, senior assistant, and D. McBride, I. Ferguson, and R.A.F. Grieve, junior assistants. The remainder of the area was covered in I965 with about 150 square miles in the southeast quarter being mapped in semi-detail and a further 300 square miles in the northern half of the area being covered by reconnaissance mapping. Assistance in 1965 was provided by R.A.F. Graham and W. McCrindle, senior assistants, and I. Ferguson, R. Holland and J.P. Scholz, junior assistants. Mapping was done on base maps of ^ mile to—1—inch -scale supplied by the Cartography Unit of the Ontario Department of Mines and traverses were spaced roughly at ~i to 2 mile intervals. Outcrop locations and outlines were determined from air photographs -of ~i m±3re~^ttr-l inch acalc, or from pace-and-compass measurements tied into recognizable features on base maps and air photographs. Information from prospect plans and drill logs in the assessment work files of the Ontario Department of Mines and information derived from aeromagnetic maps (0.D.M.-G.S.C. Nos. 2157G, 2158G, 2168G and 2169G) has also been used in preparing the map. A preliminary uncoloured geological map of the south- west quarter of the area, on the scale of jz-milo to 1- inch, was released in April 1965 (Map No. P.294) and four uncoloured an maps of- the same scale, together covering the whole report area, were issued in February 1966 (Map Nos. P.332, P.333, P.334 and P.335). The final coloured maps Nos. Oooo &»d 000Q. ///>c/> ?o (back pocket) are reproduced on the scale of a-mile tt> 1 inohh. Acknowledgment s The author appreciates the cheerful and capable co-operation of senior assistants M.E. Coates, R.A.F. Graham and W. McCrindle all of whom conducted independent mapping in the area. The accurate and willing work of junior assistants I. Ferguson, R.A.F. Grieve, R. Holland, D.McBride and J.P. Scholz is also greatly appreciated. Information on trails in the Dotted Lake-Mobert Creek area provided by B. Fairservice of Manitouwadge was of considerable help and thanks are also due to E. Mitchell, Forest Ranger with the Department of Lands and Forests in Manitouwadge. Previous Geological Work Geological examination of the area has been very limited. The general geology of the area was described by J.E. Thomson (1931) as part of the Hgrnlor-White Lake area ' -.;>Z- report in 19>31'. More recently the south part of the area was covered in an examination by M.W. Bartley and T.W. Page for the Canadian Pacific Railway Company (1957) in 1957. Otherwise the area has received little attention. Topography The northwest corner of the area is drained by north— flowing creeks, originating from lakes such as Fourbay Lake and Gaffhook Lake, which ultimately join the Pic River west of the area via Nama Creek. In the remaining area drainage flows south via the Black River and its tributary creeks and, in the extreme southeast corner water^gathered in #White Lake drains into White River south of the map-area. The Black River meanders roughly south-southwest through the centre of the area and occupies a low, wide valley floored by a thick Pleistocene succession of varved clays overlain by bedded silty sands with coarse sands and minor gravels. These glaciovlacustrine deposits extend back up the valleys of tributary creeks and at many places the banks of the river and creeks consist of steep clay and sand cliffs up to 50 feet above water level. Similar clays and sands occupy the valleys of creeks which drain into Nama Creek in the northwest of the area, and these deposits are extensions of clays and sands flooring the Pic River valley to the west of the map-area. The rocks underlying the area west of the Black River and north of Mobert Creek are predominantly granitic. These granites are well exposed and high bare ridges are common. The trend of th ese ridges is controlled by the gneissosity and jointing, and northeast-southwest trending 7 valleys have been accentuated by glacial scouring. In the area east of the Black River and south of Mobert Creek the topography, where it is not influenced by drainage or glacial scouring, is largely controlled by the underlying rock type. The topography in areas underlain by paragneisses, acid pyroclastic rocks and granitic rocks consists generally of low rolling ridges interspersed with swamp and little rock exposure whereas the mafic metavolcanic rocks commonly form high bare ridges which conform to "the structural trends in these rocks. (?fa&**»//$ w* I O^JMO) '/ In the main drainage valleys, as mentioned above, drift cover is thick and rock exposures are few. Elevations in the area, other than in the Black River valley, range between 1000 and 1400 feet above sea level. Natural Resources Much of the area has been cut or burned over so that thick tree cover now consists of older hardwood, mostly trembling aspen and white birch, mixed with a dense younger growth of softwoods, predominantly black spruce and balsam with some jjackpine in granitic and in sandy areas to the north. Scattered areas of cedar and tamarack occur around lakeshores and in the swamps. Two fires, one in 1923 and another in 1934> affected large sections of the area extending as an almost continuous swath about 6 miles wide, southwest from McGraw Lake to Alberta Lake, a distance of about 26 miles. Other smaller sections have been burned. In 1899 a section 2 miles wide extending south from Twist Lake to Roger Lake was burned and, in 1941 fire destroyed a I2 mile wide section paralleling the west shore of Kaginu Lake in Gertrude township. A large part of the map-area lies in the Black River watershed and the timber resources of this section are held by the Ontario Paper Company Ltd. The present highway to Manitouwadge, Highway No. 6l4,in part follows old timber cutting roads. Old roads in the south of the area are no longer maintained but present cutting operations, which are continuing northeast of the map-area, are serviced by a private gravel road which branches off Highway No. 614 just north of No. 1 Lake and follows the Black River and Macutagon River northeast. Between 1950 and 1957 a large section was cut over between the Black River and the east limit of its watershed extending from the south of the area north to Dotted Lake, and in a 2-mile wide belt on the west side of the Black and Macutagon Rivers from Barehead Creek to the north of the area. The northwest corner of the map-area lies within the Nama Creek watershed and the southeast of the area lies in the White River watershed. The timber resources of these sections belong to the Marathon Corporation of Canada Ltd. and the Abitibi Paper Company Ltd., respectively. Most of the Abitibi section has been cut over and there are numerous abandoned camps and overgrown trails in this region , The Marathon Corporation limits lie within Grenville and Leslie townships. Cutting operations started in this region in 1948 and are continuing. Access to Fourbay Creek is possible via an old Marathon Corporation cutting road which branches south at Nama Creek from the Industrial Highway west of Manitouwadge. The area is readily accessible from Trans-Canada Highway, Ontario Highway No. 17> and large numbers of tourists use the roads in the area. Lakes accessible by road are extensively fished and fishermen and hunters are flown into many of the less accessible lakes, in the west and northeast of the area from White River airbase. Pike and pickerel are relatively plentiful in most lakes but Dead Otter and Dotted Lakes provide poor fishing although there are pike in the small lakes just north of Dotted Lake. Speckled trout have been caught in Mobert Creek, Dotted Creek and in Amwri Creek. Moose, bear, beaver and partridge were seen frequently in the area and bobcat, deer»fox and otter were also seen. There are a number of trap lines in the area operated by trappers from Manitouwadge and Heron Bay. There are no permanent residents in the area but the gate operator on the Ontario Paper Company road lives seasonally in the gatehouse at the junction with Highway No. 614 and the Department of Lands and Forests maintain a towerman at Dead Otter Lake during the fire season. The tower is accessible by a rough road from Highway No. 614 to Dead Otter Lake and then by walking trail south from the towerman's cabin on the lakeshore. In addition the Ontario Department of Highways operates a road maintainance camp on Highway No. 614 just north of Barehead Creek. General Geology The bedrock in the area is all of Precambrian age but thick unconsolidated varved clays, silty sands and gravels of Pleistocene and Recent age occur along the major drainage valleys. The northern half and western parts of the area are underlain essentially by granodiorite gneiss which constitutes part of a large domical batholithic mass. parts In the south and southeast^of the area the rocks consist of an intensely folded series of metavolcanic, pyroclastic and metasedimentary gneisses metamorphosed to almandine amphi- bolite facies, and intruded by synorogenic serpentinite, peridotite, and amphibolitic metagabbro sheets and lenses, and granodiorite gneiss. These are all intruded by younger plutons of massive augite and hornblende-biotite granodiorite, •^QA &L\^i /QsT&s- \Cc£< cil C' quartz monzonite and^gg^anite. These younger intrusive rocks have a relatively high magnetic response and the general outline of the plutons can be determined from aeromagnetic maps (Maps 2157G, 2158G, and 2168G). The serpentinite- r\ peridotite intrusives are also readily apparent on these maps. 11 Finally the whole area was dissected by swarms of diabase dikes which intrude all the above mentioned formations. Retrogressive metamorphism appears to be associated with late faulting and shearing in the area and produces much epidote in formations of basic composition and converts biotite to chlorite in the pelitic and quartzo-feldspathic formations. None of the rocks in the map-area have-been dated but ages have been determined in the adjoining Manitouwadge area for biotites in the paragneisses (,1961), leads in the Wilroy ore body Q965) and feldspars in granites and pegmatites IWM *i »/ cutting these f»1965). These determinations indicate that the last maj'or metamorphism of the rocks occurred about 2600 million years ago, therefore the metasedimentary and metavolcanic rocks would be considerably older than this. The same granites and pegmatites that occur in the Manitouwadge area are present in the Black River area and the metasedimentary and metavolcanic rocks of the two areas are believed by the writer to be equivalent. All the rocks in the area therefore, other than the diabase dikes, can reasonably be regarded as of Archean age. A Whole Rock K-Ar age determination on a diabase dike outcrop about 4 miles south of the map-area (1965) gave an age for the rock of 2320 million years. It is probable that there are a number of different ages of diabase dike in the area. TABLE OF GGfiTE-NT-S- fo£rf$T1 »/U$ CENOZOIC Pleistocene - Varved clay, silty sand, sand and Recent and gravel. ;S£eat Unconformity PRECAMBRIAN PROTEROZOIC Diabase 4±ksaB— a / quartz diabase, porphyritic diabase. ARCHEAN Late Silicic Plutonic Rocks H •f hornblende-biotite granodiorite and quartz monzonite, biotite granodiorite, augite granodiorite, aplite, pegmatite, feldspar porphyry, hornblende-feldspar porphyry, muscovite granite, augite syenite and lamprophyre dikes. Intrusive Contact Early Silicic Plutonic Rocks H f Mbrnblende-biotite granodiorite gneiss, biotite granodiorite gneiss, feldspar augen gneiss, migmatite. Intrusive Contact Mafic and Ultramafic Intrusive Rocks N f irietagabbro, serpentinized peridotite, anorthositic gneiss. Intrusive Contact Metasedimentary Rocks f- Conglomerate, greywacke, arkose, biotite- and muscovite-quartz-feldspar gneiss, . sillimanite gneiss, garnet-biotite schist. Acid to Intermediate Metavolcanic, Pyroclastic and Metasedimentary Rocks f- ^acitic and rhyolitic flows, flow breccia, agglomerate, tuff, greywacke, iron formation, biotite gneiss, -wiymulitu. Mafic to Intermediate Metavolcanic Rocks f amphibolite, hornblende gneiss, pillow ' lava, 4»igftittliLt3. •Bacio- to Intermediate Metavolcanic Rocks An irregularly shaped, highly folded mass of mafic metavolcanic rocks occupies the south-central part of the area. The original total thickness of these metavolcanic rocks cannot be determined as the formation is in contact with granitic intrusive rocks over much of its length. The maximum unfolded thickness of the mafic metavolcanic formation as it occurs in the area would probably be less than 4000 feet. The rocks of this formation consist principally of metamorphosed volcanic flows of basaltic to andesitic composition, and pillowed flows make up a large part of the sequence. The most common rock type is a fine-to medium- grained mafic amphibolitic rock, dark green to dark grey or black in colour, and usually foliated with planar or fibrous orientation of hornblende grains. Quite frequently the foliation is not strongly developed and is difficult to detect. Schistose rock occurs only locally in shear zones and occasionally, for example west of No. 2 Lake, very fine-grained amphibolites develop a slaty structure. Medium— / to coarse-grained flows are also present. These medium-/to coarse-grained amphibolites may be equigranular or may consist of poecilitic hornblende grains up to 2 inch in diameter enclosing medium-yto fine-grained feldspathic or saussuritic material, as in the area north of Pinegrove Lake. Pillow lava is found throughout the area and is generally fine-/to medium-grained but coarse-grained pillowed flows do occur, for example northwest of Dead Otter Lake. Quite often the centres of the pillows are lighter in colour than the margins. Most commonly this is apparent as a slight difference in the shade of green of the weathered surface between the centres and the rims but in some outcrops, for example on the Dead Otter Lake road opposite the south end of No. 3 Lake, the difference between the pillow core and rim is very marked, the cores being light buff in colour and the rims dark green. The pillows are invariably stretched and the shearing may be severe enough to destroy the pillow structure and convert the rock to a laminated hornblende gneiss with dark green and light green or buff laminations an inch or less in thickness ^liutu'-'S?)*. Lamination is also developed in some non-pillowed flows. In coarse-grained lavas lamination is generally poor or absent but in finer grained flows it is often well developed with alternating light and dark green bands. Grain orientation is also better developed in the finer grained lavas. Good exposures of finely laminated hornblende gneiss outcrop in the area west of No. 4 Lake . between Roger and Olga Lakes.and along the northwest side of Phil Lake. Epidote^sometimes develop^ as a major consti tuent in the finely laminated gneisses. Very occasionally porphyritic feldspar is present in the fine—grained mafic lavas, for example in the pillowed lava in the railway cut about 6000 feet north of Phil Lake, and scattered exposures of vesicular and amygdular lavas were found. Disseminated pyrite is found throughout the mafic metavolcanic rocks and locally small concentrations of pyrite occur in shear zones as for example south of Dead Otter Lake, or on the shores of Theresa Lake. The various types of amphibolite, coarse-grained, fine grained, pillowed, non-pillowed etc. grade into each other indicating that the variations in texture and structure are related to variations in cooling rates, in the effects of shearing etc. in individual flows and not to the existence of separate flows with each of these different textures or structures. The contacts of individual flows were rarely seen, and intrusive metagabbroic amphibolite identical in appearance to the coarse metavolcanic amphibolites intrude the metavolcanic and metasedimentary rocks. It is possible, that there is more intrusive amphibolitic material present than is indicated on the map but it is not believed to be quantitatively important. Since flow contacts are rarely seen measurement of flow thicknesses is not possible. The contact between the mafic metavolcanic rocks and the,granodiorite gneiss is very poorly exposed being, for A A the most part, buried beneath thick drift cover. The granodiorite gneiss is intrusive into the metavolcanic rocks with some interlayering of the two rock types over a narrow zone of about 100 feet and the granodiorite is 16 hybridized slightly to a more mafic hornblendic granodiorite. The contact between the metavolcanic amphibolites and the massive biotite leucogranodiorite of the Dotted Lake Batholith is better exposed. Good exposures of the contact can be found on the southwest side of Dead Otter Lake. The leucogranodiorite is intrusive into the metavolcanic rocks with sharp contacts and generally in the contact area it is slightly finer grained and main darker than in the interior of the/mass. The granodiorite in contact with the metavolcanics is invariably sheared and this shearing can be severe causing the formation of a granodiorite gneiss. The shearing parallels the contact and the foliation of the metavolcanic rocks. Scattered granitic dikes are present throughout the area of metavolcanic rocks but in the region between Garoche Lake and Olga Lake the number of granitic dikes and sheets intruding the metavolcanic rocks increases to the extent that the rocks are essentially migmatites. Migmatite is also developed locally around some of the smaller granitic bodies intruding the metavolcanic rocks, for example in exposures in the railway cuts north of Phil Lake (Photo No. 3). The bulk of the mafic metavolcanic rock formation consists of amphibolite and hornblende gneiss composed essentially of dark green hornblende, and plagioclase feldspar ranging in composition from oligoclase to andesine. The plagioclase grains show simple and oscillatory zoning. Quartz is common and most sections are cut by quartz stringers but large quartz veins are not common. Garnet is rare but magnetite, apatite, sphene, chlorite and epidote are common accessories. Epidote minerals are developed in the amphibolites and hornblende gneisses in varying degree. Epidote is absent or an unimportant accessory in most of these rocks except in the amygdular flows where epidote is an important constituent concentrated in the original amygdular spots with biotite and feldspar and surrounded by hornblende and plagioclase of the ground mass. This retention of the original compositional inhomogeneity of the rock indicates the very limited range of diffusion during metamorphism of these rocks. In general where epidote is an important constituent of the no.-amygdular flows it appears to be of secondary origin and related to fracturing and faulting of the rocks. In slightly altered rocks jM4 epidote mineral is largely confined to thin stringers with slight dusty alteration of the plagioclase in the rock adjacent to the stringers. In more intensely altered rocks which commonly seem to occur near faults, for example in the railroad cuts north of Phil Lake, the epidote pervades the whole rock and is frequently accompanied by hematitic staining. z. The granitic rocks in the fault zone are similarly epidotis'ed and hematitized. Most of the epidote is secondary in origin and the primary metamorphism in the area appears to have converted the vol canic flows to rocks composed of hornblende plus oligoclase- andesine feldspar with scattered garnet and minor epidote. These rocks would be ranked in the almandine amphibolite metamorphic facies of Fyfe, Turner and Verhoogen (1959), and are therefore comparable in metamorphic rank with the mafic metavolcanic rocks of the Pic River and Manitouwadge areas. \ \ \. \ Disseminated pyrite is present throughout much of the mafic metavolcanic formation and small concentrations of pyrite occur in a few scattered shear zones in the metavol canic rocks. Pyritic shear zones outcrop on the shores of Theresa Lake, north and south of the Dead Otter Lake fire- tower, and on the Dead Otter Lake road. These zones appear to contain only pyrite but there are a number of other fracture and shear zones in the metavolcanic rocks which carry more interesting types of mineralization. On the yon Klein property the No. 4 showing (see p22&se ), about 800 feet west-northwest of the No. 1 showing on the Dead Otter Lake road, consists, of pyrite mineralization with some chalcopyrite in thin seams filling fractures in mafic meta volcanic rocks. This is just north of the contact with the pyroclastxc formation. The Kusins snowing.consists of a few small silicified pyritic shear zones in metavolcanic horn blende gneiss about 4000 feet southwest of the Black River. Small pods of sphalerite and galena mineralization occur in the pyritic zones. Finally, the Fairservice showing^ north of Dotted Lake, consists of two very thin seams of massive sphalerite in a shear zone with a maximum width of about 4 feet and length of about 50 feet, in mafic metavolcanic rock. Thin quartz, and epidote and carbonate stringers are common in the metavolcanic rocks but quartz veining is very rare. The general outline of the mafic metavolcanic formation is clearly outlined on aeromagnetic maps of the area (Map 2168G) due to the higher magnetic response of these rocks in comparison Sc with the surrounding granodiorite gneiss andAb-iet*ke—gra-ni-fc-e. The response is generally 100 to 200 gammas above the response of the granitic rocks and is approximately the same as the metavolcanic rocks of the Manitouwadge area. A small area of mafic metavolcanic rocks is shown along the northern boundary of the map-area. These rocks lie on the southern side of the Manitouwadge metavolcanic belt and have been described in detail by E.G. Pye (1957). Most of the exposures examined in this region outcrop along the, industrial road just west of Manitouwadge and they consist of hornblende schists and laminated hornblende schists as described by Pye. These rocks are similar to the laminated hornblende gneisses in the southern part of the Black River area except for the slightly more schistose character of the rock in the Manitouwadge area. £i licit Acid to Intermediate Metavolcanic, Pyroclastic and Metasedimentary Rocks Rocks included under this heading include salic and mafic pyroclastic rocks, dacitic flows, rhyolite, greywacke, biotite gneiss, migmatite and minor iron formation. Stratigraphically this formation lies between, and is believed to be transitional to, the older mafic metavolcanic rocks and subsequent metasedi mentary rocks. Mafic metavolcanic flows are interleaved with the pyroclastic and acid metavolcanic material and the pyro clastic agglomerates and tuffs grade into the metasedimentary conglomerates and greywackes. */ Rocks of this formation are found in a belt between 600 and 2,500 feet wide, extending from the south end of Theresa Lake northwest to the Dead Otter Lake road and then southwest through Phil Lake to the Black River, and in another mass consisting largely of pillowed dacitic flows, extending from just north of Phil Lake, northwards to about 5 mile beyond Pinegrove Lake, on the west side of the Canadian Pacific railway track. In the area extending north from about Phil Lake, on the west side of the railway track, the rocks are relatively uniform in character. They are mainly dark blue grey, fine grained, porphyritic, pillowed dacitic flows which weather a light blue grey to pink colour. Pillows are abundant and range in size up to 3 feet in diameter with darkgreen 12-inch thick selvages. The pillows appear to have been balloon- shaped originally but have been severely stretched, with the most severe stretching in the general direction of dip, essentially parallel to the hornblende lineation (Photo w*4- ). The flows have a spotted appearance due to the presence of white to pink weathering feldspar phenocrysts up to % inch in size. The pillowed, scoriaceous and massive phases which are,present are similar in composition^and grade into each other. Particularly good exposures outcrop along the west side of the railroad track, opposite Pinegrove Lake, and in this region the rocks are cut by thin stringers of feldspathic and epidotic material and by numerous dikes of feldspar porphyry, hornblende-feldspar porphyry, augiteJK syenite, amphibolite, biotite granite and diabase. Microscopic examination indicates that these metadacites now consist essentially of albitic plagioclase and hornblende with some quartz and minor amounts of carbonate, epidote, biotite, sericite and magnetite. Mafics" total between 25 and 30 percent. The plagioclase grains are generally sericitized and many have a s|gpJve texture, being packed with small rounded inclusions of quartz and needles of hornblende. The second belt of rocks, extending from Theresa Lake to the railroad tracks at Phil Lake, is extremely heterogeneous. In the Theresa Lake region the rocks are interbedded agglomerates and tuffs. The agglomerates are laminated and contain abundant, len&ed>^ porphyry fragments in a hornblendic and epidotic m atri$. The fragments are stretched to 1 foot or more in length. The tuffs are thinly laminated and commonly have h hornblende-rick garnetiferous bands up to 6 inches thick alternating with grey-buff felsic layers of similar thickness. Numerous intrusions of aplite, granite gneiss and amphibolite cut these rocks and the aplitic and granitic dikes are commonly stretched and boudinaged. Further west, in the region of the Von Klein Property (see map ), similar agglomerate and tuff are present but in addition, thin, discontinuous beds of biotitic quartzite, greywacke, garnetiferous siliceous tuff, iron formation, metarhyolite and rhyolite breccia are also present, and thin, pillowed, mafic to intermediate lava flows are interbedded with these rocks. I f,l, /Ji 3 „ In the area around the Von Klein No. 2 showing (Fl-4%e ) the predominant rock type is a strongly foliated garnet-biotite- muscovite-quartz-oligoclase gneiss. The showing itself occurs in a large block of amphibolite rafted in a rhyolite breccia, whi-cit is only slightly foliated butA similar in composition to the surrounding gneiss except for a lower biotite content and an abundance of angular,inclusions ranging in composition from amphibolite to rhyolite. It is believed by the writer that the rhyolite breccia forms a plug in the surrounding biotite-muscovite gneiss which may be metarhyolite or meta- arkose material. No contacts between the breccia and the gneiss were located and the general impression was of gradation between the two rock types. Iron formation was found in --©a^ly two outcrops about 250 feet south of the Von Klein No. 1 showing and consists mainly of quartz with mafic hornblendic lenses, and streaks and stringers of pyrite and pyrrhotite. The pyritic band is about 8 feet wide and is bounded by agglomerate on the north and a mafic volcanic flow to the south. The tuff units are extremely heterogeneous in this region and in some outcrops, for example on the south side of the Dead Otter Lake road about 130 feet west of the Von Klein No. 1 showing, there appears to be two distinct phases present. One of these phases is light grey in colour and consists of quartz, andesine and biotite with minor garnet and chlorite. It occurs as irregular blobs and streaks, containing rounded fragments up to 8 inches long, mixed with a second dark green, mafic phase of hornblende.plagioclase and garnet, also containing scattered fragments. Compositionally these are not unlike some of the pillowed flows in the region which have light cores and wide dark selvages which when sheared resemble laminated tuffs but the irregular blobs and streaks of the light coloured phase are not derived from original pillow structures, and fragments are present in the rock. It is possible that this is a variety of welded tuff. Further west again rocks of this formation are well exposed on Highway 614 for about 2 mile north and south of Summers Lake. On the highway opposite Summers Lake itself there are excellent exposures of agglomerate. The fresh rock is dark green grey in colour with light grey or yellow green /e^ncf/aP* porphyritic leased fragments. The ground"~mass and fragments weather dark green and buff respectively. The rock is well pa./~*e>-//e / foliated with orientation of the fine-grained hornblende of the matrix and 1-ensing-e-f the fragments. The fragments are predominantly acid feldspar porphyry and range in size up to about 4 inches. Feldspar phenocrysts or crystal fragments are also scattered about in the matrix. The matrix is essentially hornblende and oligoclase with some quartz, biotite, chlorite and epidote, while the fragments are mainly quartz and oligoclase with epidote and chlorite and minor hornblende. The fragmental nature of the rocks is most apparent on horizontal surfaces. Elongation of the fragments seems to be more intense in the direction of dip so that in vertical faces the rock has the appearance of a light and dark green laminated hornblende gneiss (Photos & o~/>) . On the east side of the highway, north of Summers Lake the laminated tuff and agglomerate is invaded by irregular masses of dacitic porphyry similar in appearance to "the dacitic flows K west of the Canadian Pacific ^railway tracks. South of Summers Lake a rock believed to be a metamor- .r /' lie 11 phosed acid* flow outcrops on the west side of the road just north of a band of mafic hornblende gneiss. The rock is fine-grained, thinly laminated and white to light grey in colour with occasional 1 inch wide hornblende-rich laminae. In part the rock is garnetiferous and in part irregular porphyritic blebs are also present s^jgegmed with tinelaminate d material. The lamination is essentially straight but minor swirls are present. Similar rocks were encountered southwest of the highway on the C.P.R. tracks and these are intruded by numerous dikes of feldspar porphyry, hornblende-feldspar porphyry, and biotite granite. Rocks of this formation continue southwest of the C.P.R. tracks and agglomerates are still present but metasedimentary material in the form of biotite-quartz-feldspar gneisses becomes important and sxithwest of the Amwri Lake road a strong magnetic anomaly was noted in the vicinity of a small outcrop of iron formation composed of thin laminations of quirtz pyrrhotite.and magnetite. ii/in c The pyroclastic-aeid- metavolcanic formation appears to fade out east of Theresa Lake into mafic metavolcanic rocks While in the southwest it appears to grade into metasedimen- tary formations. The greatest thickness and heterogeneity silicic of pyroclastic and a-eid- flow material occurs in the region of the Von Klein property and Summers Lake. This fact and the presence of a rhyolite breccia plug suggests that this region was the locus of explosive acid vulcanism and that the range of distribution of products from this vulcanism was relatively limited;in the order of a 5-mile radius. All the rocks of this formation have been metamorphosed to the almandine amphibolite facies. The rocks present a wide range of compositions from msa=idte amphibolite to s-aJ ic metarhyolite and heterogeneous mixtures of any of these compositions may occur in single rock units. In the more salic rocks the common metamorphic mineral facies consists of garnet-biotite-quartz-plagioclase with muscovite an important constituent in the metarhyolitic rocks in the yon Klein property. In the mafic phases of the agglomerates and tuffs the common mineral association is hornblende- biotite-quartz-plagioclase with garnet plentiful in some outcrops and absent in others. The plagioclase in these rocks ranges from sodic oligoclase to andesine with generally more calcic plagioclase in the mafic rocks and more sodic plagio clase in the salic rocks. Epidote is present in many of the rocks but in general it is a minor constituent and of secondary origin associated with chlorite and sericite in veins and alteration patches replacing plagioclase and hornblende. However, in some agglomerates some of the epidote is of primary metamorphic origin. In the agglomerate outcrop on Highway 614, opposite Summers Lake, the groundmass is quite mafic and consists essentially of hornblende-biotite-quartz- plagioclase while the fragments, which are much less mafic, consist of epidote-quartz-plagioclase with minor hornblende. This again illustrates the very limited range of diffusion during metamorphism of these rocks. There is little mineralization in the main mass of these rocks but a number of mineralized showings are located in the Von Klein property a short distance east and west of the Dead Otter Lake road. In the two major showings in this area copper-nickel mineralization is confined to large blocks of amphibolite rafted in rhyolite breccia or silicic tuffs. There are a number of large amphibolite fragments in the area but not all of these are mineralized. Other small chalcopy- rite showings in the region of the Von Klein property occur in shear zones in the tuffs and in shear and fracture zones in the mafic metavolcanic rocks on the north side of the pyroclastic formation. Metasedimentary Rocks South of the pyroclastic and mafic metavolcanic formations metasedimentary rocks occupy a large roughly triangular-shaped area with the base in the south extending from White Lake west to Gowan Creek and with the apex lying just south of the Von Klein property. Large plutons of hornblende-biotite grano- diorite intrude the metasediments so that part of the triangular area is underlain by these acid intrusive rocks. The meta sediments extend beyond the southern limit of the map-area and the section mapped represents only part of a large belt of metasedimentary rocks roughly centred on Highway 17 and extending approximately from White Lake in the east to beyond Rouse Lake in the west. Tight isoclinal folds have formed in the metasediments due to shear folding and the overall similarity in composition of the metasediments makes it impossible to determine the absolute thickness of sediments involved. The dominant rock type in the sedimentary formation is a biotite-quartz-feldspar paragneiss very similar lithologi- cally to the biotite-quartz-feldspar gneisses of the Manitouwadge area. However, over much oj- the area, especially adjacent to the pyroclastic formation in the north, there is much conglomerate interbedded with the biotite-quartz-feldspar paragneiss, whereas there are no conglomerates in the Manitouwadge area. In the map-area no contacts of the meta sedimentary formation were found exposed; however the position of the formation contact is relatively easily located in the eastern part of the area as, in this region, the metasediments are in contact with the mafic metavolcanic rocks and there is an abrupt change in lithology. In the west part of the area, on the other hand, the contact is more difficult to determine; the metasediments are in contact with the pyroclastic formation and there is a gradation between the pyroclastic tuffs and agglomerates.and the sedimentary biotite paragneisses and conglomerates. The distinction is made more difficult by the fact that the rocks in this region are more strongly sheared than those further east and all the fragments are stretched out parallel to the foliation. In general the biotite paragneisses and conglomerates are biotitic and noticeable amounts of granite and quartz fragments are present whereas the pyroclastic rocks are hornblendic, feldspar porphyry fragments are most common, and no granite fragments were noted. Exposure of the metasedimentary rocks is very poor and within the main mass of metasediments the gross composition is relatively uniform with the exception that conglomerate bands are present in the northern part of the sequence. The principal rock type is a fine-grained, light and dark grey banded, well foliated biotite-quartz-feldspar gneiss. Small red garnets are present in many outcrops but these are so sparsely distributed in-the rocks that they may be over looked. The biotite content of the rocks is generally greater than 5 per cent but less than 15 per cent, and the dark and light banding in the rocks reflects differences in the biotite content of the layers. The banding varies in thickness from very thin to several feet and generally the thicker bands are of the lighter coloured, less biotitic type. A few outcrops of garnet-biotite schist were found in the regions north of Amwri Lake and west of No. 2 Lake. These rocks are more biotitic than the typical paragneiss and as a result they are more schistose in character. Conglomerates are abundant in the area between Etna Lake and Musher Lake and in the area between the Amwri Lake road and the Black River. The effects of folding are difficult to assess therefore determination of the thickness of the conglomeratic section of the metasedimentary formation is not possible, but, the greater areal extent of the conglomerates in the east part of the area as compared with the west suggests that they may possibly thicken from west to east. The conglo merate is interbedded/and occurs in graded beds,with biotite- quartz-feldspar paragneiss which itself may contain small rock fragments and is commonly in the high biotite range of 15 per cent particularly in the Amwri Lake road. The paragneiss would seem to have been greywacke originally. The conglomerate beds range in thickness from 6 inches to 10 feet and are inter- bedded with greywacke layers varying in width over the same range. Most commonly the beds are between 6 inches and 1^ feet wide. Pebble density is extremely variable. Some beds are densely packed while others contain only scattered pebbles and in single beds pebble density varies. Pebbles of various compositions are present including granite, quartz, feldspar porphyry, arkose or quartzite and occasionally amphibolite. No very large fragments were noted and the original pebbles were probably never more than a few inches in diameter. The pebbles are now mostly stretched, parallel to the foliation, and the maximum observed length of these elongated pebbles, is about 1 foot with the majority having stretched lengths of between 3 to 6 inches. The pebble stretching appears to have been more intense in the western part of the area. In the Amwri Lake road region the metasediments grade into the pyro- clastic rocks and in this area there are occasional thin hornblende strata interbedded with the conglomerate and grey- wacke. Graded bedding is not common and was generally inconclusive as regards top directions. The paragneisses consist essentially of quartz, oligo- clase, and biotite with appreciable amounts of microcline and minor garnet in some outcrops. Accessory minerals include sphene, magnetite, apatite and zircon, and secondary chlorite, muscovite, sericite3epidote and pyrite are developed to a small extent. The biotite is brown and occurs predominantly as elongated flakes in parallel to subparallel alignment in a granoblastic matrix of quartz and feldspar. Pleochroic haloes are common in the biotite and in some localities the biotite is slightly altered to chlorite or muscovite. When garnet is present it is generally as small anhedral to subhedral grains up to 2 millimetres in diameter. These small grains rarely contain inclusions and may be partly altered to biotite and muscovite. The garnet grains are occasionally elongated parallel to the foliation. Slight sericitization and saussuri- tization of the feldspar is common. A distinctive band of muscovitic quartz-feldspar gneiss a. s occurs along the northwest contact of the met^dedimentary forma tion; the best exposures are in the small creek on the east side of the Black River north of Amwri Creek, and on the Amwri Lake road. The band varies in width from about 200 feet to 400 feet and was traced over a distance of about 2 miles. The gneiss is generally fine-grained and thinly laminated with light grey to white laminae between l/8 inch and "4 inch thick. The rock is dominantly quartzo-feldspathic with minor muscovite and a very low chlorite and biotite content. Fracture planes parallel the lamination and these are coated with silvery muscovite and minor chlorite. At some points along the belt coarse quartz augen are developed in the gneiss and cause bulging of the laminatbn. The rock commonly has a rusty weathered surface due to presence of small streaks, lenses and disseminations of pyrite. On the Amwri Lake road a very few, small, scattered fragments ranging in size up to 1^ inches by "5 inch were noted in the rusty weathering gneiss, and on the north side of the creek bed about 500 feet northeast of the Black River what appeared to be a 6 inch by 4 inch oval cobble was observed. In general fragments were not observed in the gneiss outcrops. Thin section examination revealed that some of the laminae in the gneiss are graded indicating that the lamination is a bedding feature of sedimentary origin. The rusty muscovitic gneiss is intruded by irregular dikes and sheets of granite and feldspar porphyry and shearing has occurred parallel to the lamination in the gneiss as indicated by offsetting of granitic dikes and granulation of quartz in thin sections. Right-/and lefthanded strike separations of /A between 4 inches and 6 feet occur on cross cutting fractures. The right-handed faults vary in strike between N70W and N60W and the left-hand faults between N10E and N25E. The rusty gneiss consists essentially of quartz, plagioclase and minor biotite with accessory magnetite, sphene, tourmaline and zircon. The biotite is almost completely altered to chlorite, and biotite and feldspar to sericite and muscovite. Minor secondary epidote and carbonate are present and euhedral to subhedral pyrite with some pyrrhotite is important locally. It is probable that the rock was originally a greywacke meta morphosed to a biotite gneiss and subsequently altered by sericitization and chloritization and the introduction of pyrite. A small outcrop of intensely crenulated muscovite gneiss outcrops about 100 feet east of Highway 614, on part of the old road, about 7000 feet south of the junction with the Dead Otter Lake road. The rock appears to be an intensely sheared and altered paragneiss now consisting essentially of albitic plagioclase and quartz with abundant muscovite^some chlorite., and scattered accessory pyrite. The muscovite is developed at least in part, by alteration of the feldspar. The outcrop is close to the south contact of a large granodiorite pluton and it is possible that the alteration and shearing of the paragneiss may be related to the intrusion of the grano diorite. The yon Klein property lies on the north side of this granodioritejand muscovite is an important constituent in some of the pyroclastic and metarhyolite gneisses in that area. Only one outcrop of sLllimanite-bearing paragneiss was found in the area and this is located on Highway 614, in the road cut just north of the railroad crossing opposite East Barbara Lake. The sillimanite occurs in garnetiferous layers 3 to 4 inches wide in a band about 6 feet wide in typical biotite-quartz- feldspar paragneiss. The sillimanite gneiss is dark grey in colour, mediumyto fine-grained and has a crenulated foliation. The rock appears to be slightly richer in biotite than the typical paragneiss and contains appreciably more garnet. The small euhedral red garnets range in size up to about 3 m/m. The sillimanite grains range in size up to ^ inch long by l/8 inch wide and often have a bluish bladed appearance but the bladed grains commonly have frayed fibrous terminations and the sillimanite also occurs as groups of colourless needles which may weather white on surface. Thin section examination indicates that the rock consists essentially of sillimanite, garnet, biotite, quartz and oligoclase with accessory magnetite, apatite, and zircon and secondary muscovite and chlorite. Foliation in the rock is imparted by orientation of the biotite grains. The foliation is folded into small crenulations and also diverges around garnet and sillimanite grains. The biotite occurs as brown lath-like grains showing slight alteration to chlorite^, and pleochroic haloes are common. The garnet grains are subhedral to euhedral. They contain very few inclusions but they are surrounded by haloes of fibrous mica and quartz and some are partially pseudomorphed by biotite and muscovite. The sillimanite porphyroblasts consist of bladed grains fraying out at the ends to fibrous swarms and these grains appear to be curved in association with the crenulation of the foliation. Very fine-grained dusty biotitic stringers parallel the crenulated foliation. These appear to be zones of incipient alteration of the biotite to sillimanite and the larger sillimanite porphyroblasts can be seen growing accross these zones and replacing biotite. Muscovite also appears to replace the biotite. The textures suggest that the paragneiss was initially metamorphosed to a biotite gneiss and that subsequent shearing produced crenulation of the foliation and that the sillimanite developed during or in the waning stages of the crenulation. In the area south and west of Tri Lake two outcrops of distinctively coloured and laminated meta-arkose were found within the main body of the mafic metavolcanic formation. The rock is a very fine—grained, pink weathering,thinly laminated quartzo-feldspathic metasediment. The laminae range up to ~i inch in thickness and may be pink, buff or light grey in colour. The rock consists of about 35 per cent anhedral, rounded to $7 irregular shaped, quartz grains mixed with about 57 • 5- Ver cent similarly shaped grains of feldspar. The feldspar is albitic plagioclase very much clouded by a dusty sericitic alteration. 8 The rock contains about 7-*-5 per* cent muscovite which occurs as poecilitic plates and small laths which have grown parallel to, and across the lamination in the rock and may be related to the sericitic alteration of the feldspar. Trace amounts of epidote and chlorite occur together as scattered grains associated with dusty patches of alteration and epidote also occurs in thin veinlets cross-cutting the rock lamination. Some dusty hematite is associated with these veinlets also. In the outcrop about 3300 feet west of Tri Lake the meta-arkose is tightly folded into small isoclinal shear-flow folds plunging southwest. No contacts were found between the meta-arkose and the mafic metavolcanic rocks. Throughout the area the paragneisses are invariably intruded by stringers of quartz-feldspar and granite and these stringers are frequently ptygmatically folded. Sometimes these rocks are also cut by later fractures and the fracture planes are coated with epidote or hematite. The quantity of intrusive material is generally low hut in some regions the rocks are highly feldspathized and migmatized, as for example in the region around Etna Lake, around the microwave tower north of Jeanine Lake and in the vicinity of the Black River. The distinction between the tuffaceous and sedimentary rocks is extremely difficult because of this in the region around the Black River. The rocks may be laminated with granitic material parallel to the foliation or feldspar augen may develop throughout the rock. In the vicinity of the Black River the feldspars are commonly pink and this p-i-nk-ing appears to be related to thin, cross-cutting carbonate-epidote veinlets. These migma- titic gneisses consist essentially of quartz, albite or sodic oligoclase, microcline, biotite andVor)hornblende with accessory apatite, magnetite and pyrite.and secondary sericite^ chlorite, epidote and carbonate. Contacts between1 the metasedi- mentary gneisses and the large granitic intrusive bodies are not exposed but the numerous small granitic dikes and sheets which intrude the metasediments have sharp contacts, with the coarse grain of the minerals of the intrusive rocks contrasting sharply with the fine-grained nature of the metasediments. Examination of a small number of thin sections suggests that the whole of the metasedimentary formation at one stage was metamorphosed to a low rank subfacies of the almandine amphibolite facies. The common mineral assemblage throughout the metasediments is biotite-quartz-oligoclase commonly with scattered garnets and sometimes with microcline. In the only sillimanite-bearing metasediment recognized in the area the sillimanite replaces earlier formed biotite and appears to be rotated in association with a crenulation which distorts the original foliation of the rock. Muscovite is present in the sillimanite gneiss and it also replaces the biotite and commonly has Jsrown across the original foliation . The silli manite gneiss outcrops on Highway 614 just north of an intrusive granodiorite contact. Likewise, about 5500 feet north of the sillimanite gneiss outcrop a highly sheared, muscovite-rich gneiss outcrops just south of an intrusive granodiorite contact (see page §£T). In addition the metarhyolitic rocks on the south of the Von Klein property are close to the granodiorite i and are also rich in muscovite. It seems possible that a certain amount of shearing was developed in the metasediments at the contacts during the intrusion of the granodiorite plutons and sillimanite and muscovite were developed in the biotite paragneisses by contact metamorphism. Throughout the area the metasediments have suffered late sericitization, saussuritization and chloritization and in many outcrops this is related to cross cutting epidote-,and carbonate-filled fractures. This alteration reaches extreme proportions adja cent to faults and is accompanied in faulted regions by hematitization. The conglomerates are restricted to the northern side of the metasedimentary unit, adjacent to the pyroclastic and mafic metavolcanic formations, and there appears to be a simple gradation from the pyroclastic formation into the meta sediments, The pyroclastic formation in turn contains mafic metavolcanic horizons within it and appears to interleave with the main mass of mafic metavolcanic rocks to the north. There is no suggestion of a major break between any of these formations. The general impression is of a continuous depositional sequence beginning with the extrusion of pillowed mafic volcanic flows, followed by the local extrusion and S / tie i'{_ explosive ejection of aj&id metavolcanic and pyroclastic material contemporaneously with minor sedimentation and inter mittent mafic volcanic extrusion and succeeded finally, by extensive, coarse, followed by fine, clastic sedimentation. Mafic and Ultramafic Intrusive Rocks Rocks included in this group include amphibolitic metagabbro, serpentinite.peridotite, talcose dikes and saussuritized anorthositic gneiss. The amphibolitic meta- gabbro intrudes the metavolcanic, pyroclastic and metasedi- mentary formations and isolated blocks are found in the granodiorite gneisses. The serpentinite and peridotite are intruded into the mafic metavolcanic formation and the anorthositic gneiss occurs as one small body within the ^?c/t./T _ granodiorite gneiss. .. MeT^CJBMM^—^ Recognition of the amphibolitic metagabbro is frequently difficult as it is similar in appearance to coarse grained mafic metavolcanic rocks. Distinction is definite only where contacts are visible and this is rare. The amphibolitic metagabbro occurs as tji-i-n dikes and extensive sheets intruding the mafic metavolcanic, pyroclastic and metasedimentary formations. The metagabbro is itself intruded by granodiorite gneiss and later massive granodiorite,quartz monzonite and diabase. Metagabbro intrudes the metasediments along the southwest shore of White Lake and is in turn agmatiti by intrusion of diorite. A large sheet of metagabbro about 4 miles long and 2000 feet wide strikes southeasterly across the south end of Theresa Lake and intrudes agglomerates and mafic metavolcanic flows. Other small dikes of metagabbro were noted in the railroad cuts east of Pinegrove Lake intruding dacitic pillow lavas. These dikes have fine-grained margins, are intruded by the feldspar porphyry dikes in the area and are agmatitized by intrusion of granitic material (see photo K ). A hybrid mixture of amphibolitic metagabbro, diorite and granodiorite is poorly exposed southeast of Etna Lake and small masses of metagabbro are scattered within the large northern mass of granodiorite gneiss. The amphibolitic metagabbro is typically a massive, medium-.or coarse-grained, dark green rock composed essentially of hornblende with variable amounts of plagioclase, biotite, and epidote and occasionally quartz and garnet. Common accessories are sphene, apatite and pyrite, and secondary epidote, carbonate, chlorite, muscovite and sericite may be present. The rock may vary in a single outcrop from a dense green rock with little or no feldspar to a speckled white and green rock containing 20 to 30 percent feldspar or saussuritized feldspar. In areas where the metagabbro has been intruded by later granodiorite or diorite the amphibolite is frequently hybridi zed and foliated and a rock containing a high proportion of feldspar results. The metagabbro is generally brecciated, intruded and permeated from the contacts inwards by the granodiorite or diorite. Although not within the map-area a very good illustration of this feature is exposed in the road cut on Trans-Canada Highway, Highway No. 17, about 2^ miles east of White Lake, immediately west of the junction with the Regan truck road of the Abitibi Paper Company Ltd. In this location the amphibolitic metagabbro intrudes biotite-quartz- feldspar paragneiss and is in turn intruded by hornblende granodiorite along the contacts between the paragneiss and metagabbro. The hornblende in the metagabbro is often pale coloured in thin section. Zoned grains are common with cores of pale to moderately strong green colour and colourless to pale green rims. The pale colour appears to be the result of a secondary bleaching effect possibly related to the intrusion of the metagabbro by the later granitic rocks. In one thin section from a metagabbro block rafted in the granodiorite gneiss numerous quartz stringers and lenses are present in the amphibolite and bleaching of the hornblende in this section is localized around the quartz masses. Brown biotite is often present as laths and irregular/V shaped grains replacing the hornblende and in the corase— grained amphibolites the biotite is commonly concentrated in the darker coloured cores of the hornblende grains. Biotite content is usually between 5 and 10 percent and not readily apparent in hand specimen but in one exposure on the Ontario Paper Company road, about 2 mile northeast of Morley Lake, the biotite content is about 15 percent and very evident megascopically. This latter rock is also cut by mineralized fractures.and occasional, small pods, containing pyrite, chalcopyrite and pyrrhotite were found in loose blocks of this material blasted from the outcrop for road fill. Epidote is common in the metagabbros and appears to be largely of secondary origin replacing feldspar and hornblende. Carbonate and chlorite are sometimes associated with the epidote, and sericite may also develop in the altered feldspar. Garnet ^-2 was found in only one outcrop of metagabbro located on the Ontario Paper Company road about I2 miles east of the south end of Agonzon Lake. This metagabbro is intruded by grano- diorite gneiss and foliated. The garnets occur as coarse porphyroblasts up to 2 inch in diameter but more commonly 1 inch or less in a medium-grained, foliated, ground mass of dark green hornblende and andesitic plagioclase. Sphene and apatite are accessories. Quartz occurs as knots lenses and stringers elongated parallel to the foliation and when examined in thin section the hornblende adjacent to these quartz masses is noticeably bleached. The garnet grains are extensively pseudomorphed by a medium-grained intergrowth of epidote and hornblende with some brown biotite. This replacement occurs as coronas around garnet cores or may completely replace the garnet grain. (Pho-fre &—*) . The plagioclase in the rock is also slightly altered to saussurite and sericite. These metagabbros appear to have been metamorphosed initially to rocks consisting of hornblende and plagioclase with or without garnet and would therefore belong to the almandine amphibolite facies. Subsequently, due to intrusion by later granitic and granodioritic material, the hornblende was partially altered to biotite, the hornblende pal©d- In/rr-'fi -<.&i cAM-y» colour and garnet was pseudomorphed by intergrowths of epidote. hornblende and biotite. In addition plagioclase in £he rock may at this time have been partly saussuritized. These rocks are similar to the metagabbros in the Manitouwadge area as 43 described by Pye (1957). ^ n >„„ .„ „. , O Three roughly lens^-shaped bodies of serpentinized peridotite outcrop in the area. The serpentinized peridotite intrudes mafic metavolcanic rocks and is thought to be older than the biotite granite of the Dotted Lake pluton. Therefore it is grouped with the amphibolitic metagabbro intrusive rocks. These ultrate^e&ie rocks have no equivalent in the Manitouwadge area but are similar in appearance, and occurrence to the serpentinite in the Pic River area (Milne, 196x). All of the serpentinite bodies are very poorly exposed and all of them outcrop on lakeshores, the best exposures being on islands and small peninsulas on the lakes. The largest body intrudes the metavolcanic rocks on the north shore of Dotted Lake and is about 8000 feet long and 1000 feet wide. Another lenticular mass intrudes the metavolcanic rocks on the northwest shore of Theresa Lake and is about 3500 feet long by 700 feet wide. The third serpentinite mass intrudes the metavolcanic rocks in the west arm of White Lake and is 6500 feet long by 1000 feet wide. In all of these the long dimension of the intrusive body trends parallel to the foliation of the surrounding metavolcanic rocks. The location and shape of these ultrab-a-s-ic intrusives is clearly indicated by high magnetic contour ridges on aeromagnetic map 2168G (O.D.M./G.S.C.). These indicate magnetic intensities similar to the serpentinite intrusive in the Pic River area. (Aeromagnetic map 2157G). The serpentinized peridotite is predominantly massive but a few narrow shears cut the various serpentinite bodies and adjacent to the shears the serpentinite is schistose. The fresh rock may be black, greenish black or dark grey in colour but where the rock is sheared it may be yellow-green to grey- green. The rock is quite soft on weathered surface and the weathered colour is generally rusty brown to black. The weathered surface may be smooth, knotted or pitted. The rough weathering surfaces may have knots of 2 inch to the 1 inch diameter standing out in relief on the surface or the surface may be pock-marked by pits of similar dimensions. The variation in the weathered surface may reflect in part the extent of serpentinization of the peridotite. The rock is o coarse-grained to very coarse-grained with gtphitic pyroxene grains ranging up to more than 1 inch in diameter., The rock in all three intrusive bodies is similar and texturally they are relatively homogeneous. Where the rock is only slightly serpentinized the black fresh surface glistens due to the highly reflecting cleavage faces of the randomly oriented 2 inch to 1 inch diameter aphitic pyroxene grains. These grains are studded with included olivine grains 1 to 2 milli metres in diameter. Where the peridotite is extensively serpentinized the fresh surface of the rock is a dull black to dark green colour and has a?honeycomb* texture consisting of 1 to 2 millimetre dark green to black polygonal grains in a slightly lighter coloured interstitial mes+r. The polygonal grains appear to be pseudomorphed olivine grains replaced by serpentine. The interstitial material is serpentinized pyroxene. This latter texture is identical to the texture of most of the serpentinite in the Pic River area. Contacts between the serpentinite and metavolcanic rocks were observed in only two locations; on the north shore of Dotted Lake where a small mass of metavolcanic rock has been included in the serpentinite and on the northeast side of the serpentinite mass in the west arm of White Lake. In the second locality the contact is between a small apophysis of the main serpentinite body and the metavol canic rock and is line sharp between two distinct rock types. In the Dotted Lake locality the contact is sheared. Most of the serpentinite exposures are massive and relatively homogeneous with no suggestion of layering but at the north end of the small peninsula on the northwest side of Theresa Lake three magnetite rich layers strike N85°E across the trend of the long axis of the main mass, which is approximately N47°W. Each layer is about 1 foot wide and separated from the next by about 3 feet of typical serpentinite. The exposed length of the layers is short as they cross the north point of the peninsula and strike into the lake. On this same peninsula the serpentinite is intruded by two 2-fe;et wide dikes composed of coarse pegmatitic hornblende and plagioclase. The dikes have fine-grained contacts and appear to produce some alteration of the serpentinite at the contacts. These are the only dikes of this kind found in the area and the only material found intruding the serpentinite. In thin section the altered peridotite consists of large ophitic clinopyroxene grains largely replaced by tremo- litic amphibole and chlorite and containing relatively unal tered anhedral grains of forsteritic olivine. Abundant secondary magnetite is present with minor carbonate and serpentinite. The olivine grains are commonly bounded by a very thin corona of colourless, inclusion-free tremolite which is optically continuous with tremolite rich in magnetite inclusions, or having pale brownish pleochroism, which replaces the ophitic clinopyroxene. The chlorite is colourless to very pale green in colour and partly replaces the tremolite. The chlorite appears to replace preferentially the inclusion- rich or slightly coloured tremolite frequently leaving the thin colourless tremolite coronas around the olivine grains. The chlorite also occurs as vein filling with magnetite in late cross cutting stringers. The tremolite-chlorite association in the altered peridotite is similar to that found in the metamorphosed serpentinite at the contacts of the Pic 0,1 River intrusive except for the presence of fresh olivine and remnant pyroxene in the Black River altered peridotite. It is possible that the ophitic textured, knotted weathering parts of the serpentinite lenses represent nonserpentinized remnants of an original peridotxte intrusive" and that later metamorphxsm produced the tremolite-chlorite alteration. A small amount of carbonate is associated with the tremolite and this tremolite- carbonate-chlorite association indicates metamorphism of the greenschist facies. This metamorphism may relate to the late zoisitization or saussuritization in the amphibolitic rocks and the chloritization in the pelitic rocks rather than to the main regional metamorphism, On the north sh ore of Dotted Lake a light green—grey speckled, medium-/to fine-grained, massive altered gabbro is associated with the serpentinite. The gabbro outcrops north of the serpentinite on the .shore but the contact relationship is not clear because of the poor outcrop and because of the sheared nature of the rock in the vicinity of the contacts. The gabbro consists of about half and half pale coloured tremolitic amphibole and zoisite with albitic plagioclase, the latter two probably representing a saussuritic replacement of an original more basic plagioclase. This metagabbro is quite unlike the amphibolitic metagabbro and was only found in this one locality associated with the serpentinite. One talcose intrusive dike was found in the area. The dike occurs in a small outcrop about 300 feet west and 600 feet south of the Von Klein No. 1 showing which outcrops on the Dead Otter Lake road. The dike is between 5 and 10 feet wide, is of unknown length, and intrudes hornblende gneiss derived from a mafic metavolcanic flow. The dike rock is very soft and is greasy to the touch. It is fine-grained, massive,and medium light grey colour on fresh surface, weathering to light buff with a slight rusty stain. Thin section examination indicates that the rock consists essentially of talc, carbonate and very pale green chlorite with about 3 percent magnetite and minor pyrite the latter generally enclosed by rusty weathered rims. The ose dike has produced some alteration in the hornblende gneiss in contact with it. Near the contact inclusions of hornblende gneiss have been incorporated in the dike and biotite rich selvages have developed around these and in the hornblende gneiss at the dike contact. The dike is probably related to the serpentinite intrusives. ,i - ,/ , „.„„ „„. „ "\ Mf/0??/t(tSiTIC &/J&t-$J SL^Z^S The last rock type included in this group is tentatively named anorthositic gneiss. This rock was found only on the east side of No. 5 lake and appears to be intimately mixed with and possibly intrusive into amphibolitic gneiss and schist. Information in this locality is limited but the amphibolitic and anorthositic rocks seem to occur as a small mass about ~i mile in diameter enclosed by feldspar augen gneiss which is a sheared equivalent of the granodiorite gneiss further west in the area. No contacts were seen between the anorthositic material and the augen gneiss but aplitic dikes cut the amphibolitic and anorthositic material. The anorthositic rock may be massive, mediumyto coarse-grained, greenish-yellow to grey in colour, weathering light buff to pink, or laminated with 2—inch wide bands of white feldspar alternating with dark green hornblendic bands. In thin section the anorthositic gneiss is composed of coarse anhedral grains of andesine- labradorite plagioclase largely altered to a medium-grained saussuritic aggregate of epidote, pale green chlorite and abundant sericite. Epidote also occurs as stringers cutting the rock. Some euhedral sphene is associated with the epidote and a very few small grains of pyrite were noted in hand specimen. On aeromagnetic maps of the area (Map 2169G) the ?? location of the anorthositic body is indicated by a magnetic anomaly rising between 400 and 500 gammas above the magnetic intensity of the surrounding granodiorite gneiss. No significant mineralization was noted in the anorthositic body, and the anorthosite does not contain noticeable magnetite) however, there is considerable amphibolitic material mixed with the anorthosite and this may be the source of the high magnetic response. v / . —-^ y //•/£•£?} 4. tz t) T/& sJ Except for the magnetite in the Theresa Lake serpentinite body, no other mineralization was noted in the serpentinite, the talcose dike, or the anorthositic gneiss. However, the on Pic River serpentinite intrusive does not appear to contain sulphides but sulphide mineralization occurs in the country rock at several points along the intrusive contact. The Black River serpentinite bodies are probably related to the Pic River intrusive-, and, although much smaller, examination of their contacts might still be worthwhile. The major problem in such an examination is ,of course the very poor exposure in the vicinity of the serpentinite bodies and the related rarity of exposures of the contacts. Disseminated pyrite is a common accessory in the amphibolitic metagabbro and is of little importance but as noted previously mineralized fractures and small pods contain ing pyrite, chalcopyrite and pyrrhotite were found in a biotitic amphibolite on the Ontario Paper Company road, about "4 mile northeast of Morley Lake. It is interesting to note also that the richest showings of chalcopyrite-pyrrhotite JTD mineralization on the Von Klein property occur in rafted blocks of amphibolite, possibly metagabbro, in rhyolite breccia and tuff. It is possible that some mineralization is associated with the metagabbro or that in mineralized localities the metagabbro represents a favourable host rock. Early Silicic Plutonic Rocks More than half the map-area, that is an area in excess of 300 square miles, is underlain by granodiorite gneisses. The gneiss underlie most of the northern half of the area and much of the southwest quarter and extends westward into the Pic River area as ?granitic gneiss * (Formation 4> maps 2098 and 2099, O.D.M. I966), northward into the Manitouwadge area (Formation 7, map 1957-8, O.D.M 1957), and eastward beyond the map limits. This formation therefore represents part of a very large batholithic mass which is referred to here as the Black-Pic Batholith since a large section of the mass lies between the Black and the Pic Rivers. The predominant rock type of the Black-Pic Batholith is biotite granodiorite gneiss but subordinate amounts of hornblende-biot£te granodiorite gneiss, feldspar augen gneiss, xenolithic gneiss and migmatite are also present and throughout the batholith the gneiss is permeated or intruded by small irregular masses of massive leucocratic biotite granodiorite. The biotite granodiorite gneiss is grey to bluish grey in colour weathering light grey to white. The rock is essentially medium-grained but may range from medium-to coarse-to medium- to fine-grained. Biotite content is usually about 10 percent 4 but may range from about 5 to. 15 percent. A foliation due to the alignment of biotite grains is generally well developed and in many outcrops the granodiorite is laminated due to the slight variation in grain size and biotite content of layers and to the presence of thin laminae, generally between l/8 inch and 2 inch thick, of leucocratic granodiorite material intruded or segregated parallel to the foliation. The rock consists essentially of zoned oligoclase, quartz, microcline and biotite with accessory sphene, magnetite, apatite and zircon. Secondary minerals include epidote which may be abundant, and minor chlorite, sericite and carbonate. Modal analyses of two granodiorite samples are shown in Table S. The quartz and feldspar grains are anhedral with the microcline interstitial to the quartz and plagioclase. Some of the plagioclase grains exhibit simple normal zoning, they sometimes contain small rounded quartz inclusions and occasionally very small irregular blebs of exsolved microcline. The quartz invariably shows mottled strain extinction and the biotite and accessory minerals occur as interstitial trains and clusters. Hornblendic layers are occasionally present in the biotite granodiorite gneiss, for example in the railroad cut on the southwest shore of No. 6 Lake the rock at the north end of the exposure is wholly biotite granodiorite gneiss (sample No. #»-, Table ^S) but towards the south end of the exposure although the bulk of the rock is still biotite granodiorite, a few laminae of hornblende-biotite granodiorite are interlayered. In some areas the bulk of the material is hornblende-biotite granodiorite, as, for example, north of No. 1 Lake and between No. 1 Lake and Pan Lake. In the area north of No. 1 Lake the hornblendic and biotitic granodiorites are interlayered but on Highway No. 614 about 4000 feet northwest of No. 1 Lake there are indications that the biotite granodiorite may intrude the hornblendic granodiorite. The hornblende-biotite granodiorite gneiss is somewhat similar in appearance to the biotite granodiorite gneiss and in some outcrops the hornblende may be masked by the biotite so that the two rock types may be difficult to differentiate. However, in general the hornblendic gneiss is more mafic, up to about 25 percent dark minerals as compared with 15 percent in the biotitic gneiss, and the hornblende is evident in most of the outcrops. The hornblendic gneiss is a slightly darker grey colour than the biotitic gneiss, is medium—grained to mediumyto coarse-grained and strongly foliated due to the well developed alignment of the hornblende and biotite grains. The rock may be equigranular but more commonly plagioclase feldspar porphyroblasts and hornblende grains slightly coarser than the average are scattered throughout the rock giving it a spotted appearance, particularly on weathered surfaces. The feldspar and hornblende porphyroblasts are usually about 2 to 3 millimetres in size but some of the feldspar arc /" *'-J£ porphyroblasts ra-ng-e- up to about 1 centimetre. Plagioclase, quartz, hornblende, biotite and small brown grains of sphene are readily apparent in hand specimens and small grains of epidote are sometimes visible. Thin section examination reveals that a small percentage of microcline is present and accessory apatite and magnetite. Hornblende-biotite granodiorite similar to the rocks in the locations mentioned above also outcrops in the north of the area adjacent to the mafic metavolcanic rocks of the Manitouwadge area. In the latter area the hornblendic grano-^ diorite forms a relatively homogeneous and persistent mass paralleling the mafic metavolcanic contact and occurring between the metavolcanic rocks and the biotite granodiorite. This hornblendic granodiorite is the same rock as Formation No. 6a- Hornblende-biotite-quartz-feldspar gneiss, map 1957-8, mapped by Pye (1957). Pye believes, on the basis of gradational contacts between the phases and examination of chemical analyses, that "the fhornblende-biotitej gneiss was originally (mafic metavolcanicLor an equivalent, less highly metamorphosed rock, and that it represents an intermediate hybrid phase in the transformation of the schist to biotite granodiorite gneiss." In the Pic River area hornblendic gneisses occur at the contact between the mafic metavolcanic rocks and the batholithic gneisses and the writer interpreted these as hybrid rocks (Milne, 196X). In the area east of Cirrus Lake particularly the writer found that "Along the main contacts with the meta volcanic rocks the (granitic) gneiss consists largely of a mafic hybrid feldspar augen gneiss with much hornblende and epidote. Partially feldspathized xenoliths of amphibolitic metavolcanic rock are scattered in the hybrid gneiss. The contact (of the Black-Pic Batholith) is not abrupt but consists of a heterogeneous transitional zone several hundred feet wide composed of various hybrid forms of amphibolitic metavolcanic and granitic gneiss rock." L/'^''''e/ '^ //"' ./ Although the Pic River hornblendic feldspar augen gneiss is interpreted as a hybrid rock it appears to have intrusive characteristics as indicated by the presence of angular xenoliths of metavolcanic rock and by sharp contacts between the mafic metavolcanic rocks and the hybrid gneiss exposed in the northeast corner of Cirrus Lake. Similarly, in the Manitouwadge area it is the author*s experience, limited mainly to the region between Manitouwadge and Cadawaja Fault, that although the three phases, biotite grano- diorite, hornblendic granodiorite and metavolcanic hornblende schist are mixed and may be interlayered the contacts between the phases are abrupt. On the Industrial Highway about 2.2 miles west of the junction with Highway No. 614 at Manitouwadge a contact between hornblende-biotite granodiorite and meta volcanic schist is exposed on the north side of the road. The hornblende-biotite granodiorite gneiss is medium-grained with numerous small feldspar and hornblende augen giving the rock a spotted appearance on weathered surface which is quite distinct ive relative to the biotite granodiorite gneiss. Approaching the contact with the hornblende schist the hornblendic grano diorite becomes fine-grained, has fewer feldspar and hornblende augen and is a little more strongly foliated. At the contact the layers of the hornblende-biotite granodiorite gneiss}a few inches thick .are interleaved, lit-par-lit, with layers of similar thickness of metavolcanic hornblende schist, over a width of about 5 feet. The contacts between the layers are non-gradational and would seem to be intrusive. In addition, in the area around Highway No. 614 and the railway track just south of Manitouwadge, the biotite granodiorite gneiss south of the railway track contains many inclusions of hornblende- biotite granodiorite gneiss and the contacts between the two phases are not visibly gradational. Thus, although the hornblende-biotite granodiorite 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 subsequently been intruded itself by the biotite granodiorite gneiss. In the northeast corner of the map-area, east of Macutagon River and north of Twist Lake, outcrop examination was limited to the lakeshores of McGraw, No. 5, No. 7, No. 8 and No. 9 Lakes and in these locations the predominant rock type is an augen feldspar gneiss. The augen gneiss is dark grey in colour and weathers light grey to white with a mottled appearance due to the abundant light coloured feldspar augen. The rock is strongly foliated and has a typical flaser structure / with a fine-grained dark grey matrix and medium-yto coarse grained light buff feldspar augen. Quartz, plagioclase, biotite and epidote are evident in hand specimen. At first examination the rock is quite unlike the granodiorite gneiss due to its darker colour and sheared flaser structure but a modal analysis (see Table rfaj ) of the augen gneiss indicates that minera- /A logically the two rock types are almost identical and the sheared character of the augen gneiss is very obvious in thin section. The augen gneiss consists of quartz, microcline and biotite with a trace of hornblende and accessory apatite magnetite and sphene. Much of the biotite has been altered to chlorite, and secondary epidote has been derived from biotite and plagioclase. The plagioclase is also highly sericitized. The augen gneiss thus appears to be a sheared derivative of the granodiorite gneiss. In some areas the granodiorite gneiss contains abundant inclusions of amphibolite and in other areas the granodiorite, and granodiorite with inclusions, is intruded by great numbers of sheets and dikes of pegmatite, aplite, and leucocratic biotite granodiorite so that the rock outcrops are extremely heterogeneous and these areas have been desig nated as migmatite. The boundaries of the Black-Pic Batholith are not completely known, particularly east of the Manitouwadge and Black River map-areas, but within the mapped region the bath olith shows a relatively consistant relationship to the adjoin ing country rocks. In the south and southwest the batholith is bounded by mafic metavolcanic rocks of the Black and Pic River map-areas respectively, and in the north by mafic meta volcanic rocks of the Manitouwadge area. On the basis of aeromagnetic information (Map 2158G), and personal experience A in the area, the writer believes the batholith to be bounded on the northwest by a belt of metavolcanic or migmatitic metasedimentary rocks, continuous with the metavolcanic rocks of the Pic River area, and extending northeast from Huck Lake to join migmatitic metasediments northwest of Manitouwadge. The rocks of the batholith are well foliated through out, and attitude determinations indicate that in the contact areas, the granodiorite gneiss foliation is essentially conformable in strike and dip with the foliation in the adjoin ing country rock. Only in the Pic River area, south of Runnalls Lake, does the granodiorite appear to cross-cut the strike of the metavolcanic rocks. The granodiorite gneiss invariably dips beneath the adjacent country rocks and all the structures in the latter rocks dip and plunge away from the batholith. In the contact areas the foliation of the granodiorite gneiss dips between 35° and vertical, and many dips are between 45° and 75°. In the central part of the batholith, however, the foliation generally dips between 35° and horizontal with most dips between 15° and horizontal. Thus, within the area covered by mapping, the foliation of the batholithic granodiorite gneiss dips outwards or near vertical all around the contacts and is essentially flat with gentle undulations in the centre. There is no information on the open east end of the batholith but, within the known area it gives every indication of being an elongated, syntectonic, domical structure. The country rocks adjacent to -the Black-Pic Batholith appear to have undergone a moderately high rank metamorphism. The metavolcanic and metasedimentary rocks of the Manitouwadge (Pye, 1957), Flanders Lake (Milne, I964), Pic River (Milne, 1966) and Black River areas have been metamorphosed to at least the almandine amphibolite facies (Fyffe ct al-7—L9-5-9-) and the metasedimentary rocks to the east, northeast (Milne, I964) and northwest (M.E. Coates, 196 ? ) of Manitouwadge have been invaded by great quantities of granitic material converting them to migmatites. These facts, plus the domical, generally conformable, foliated character of the 00 batholith, suggest that it may be a deep level intrusive of the catazone (Buddington, 1959). However, more information is required on the metamorphic condition of country rocks away from the batholith since the almandine amphibolite metamorphic rank of the Manitouwadge, Pic River and Black River rocks may reflect a high temperature aureole around the margins of the batholith. The Black-Pic Batholith is intruded by younger, me^ozonal plutons of granodiorite and quartz monzonite, and by dikes of pegmatite, aplite, biotite granite, augite syenite, feldspar porphyry, l*mifpmwpiss$xy? and diabase. The batholith is also cut by faults and adjacent to the faults the granodiorite gneiss may be hematitized or silicified. Examples of this may be seen northeast of Gowan Lake or, around and east of Lineal Lake. In these locations the granodiorite near the fault is altered from a light grey to a pink or brick-red colour while,away from the fault the granodiorite is cut by very thin fractures along which the adjacent granodiorite feldspar, which xs normally white, is coloured pink. Yellowish green epidote stringers also cut the granodiorite in these areas and in the area northeast of Gowan Lake the red altered granodiorite is cut by a stockwork of thin quartz veins. There was no mineralization noted in the granodiorite gneiss. Late Silicic Plutonic Rocks At least five large plutons ranging in composition between granodiorite and quartz monzonite outcrop wholly or partly within the map-area. These plutrons have been named as A follows:- the Fourbay Lake Pluton in the west-central part of the area; the Gowan Lake Pluton, in the southwest corner; the Bullring Lake Pluton, located near the middle of the south boundary of the map—area; the Musher Lake Pluton lying on the south side of the mafic and a=eid- metavolcanic formations; and the Dotted Lake PI ui~.nq which outcrops in the southeast quarter of the area. There are variations in the composition of the rocks in individual plutons and between different plutons (see Table/<6J). In general the plutons become less mafic, and range from medium- to coarse-grained, tending to porphyritic, in the order listed above. Sampling was insufficient to determine whether any systematic variation in composition occurred within individual plutons. The megascopic distinction between the first three plutons; the Fourbay, Gowan and Bullring, is much less apparent than between these and the Dotted Lake P-lufooHr. The first three are more mafic and characterized by the presence of hornblende and biotite while the Dotted Lake g,lut It seems probable that there is an intrusive relationship between the leucocratic biotite granodiorite of the Dotted Lake Pluton and the hornblende-biotite granodiorite and hybrid diorite found on the west shore of White Lake. On the other hand a gradational relationship between the mafic hornblendic granodiorite and the leucocratic biotitic grano diorite is suggested by the Musher Lake Pluton which consists, on the west side, of hornblende-biotite granodiorite similar to the Gowan Lake Pluton, and on the east side of biotite granodiorite similar to the Dotted Lake Pluton. Since a possible intrusive relationship existed and megascopic distinct ion was relatively easy the mafic hornblende granodiorite and the leucocratic biotite granodiorite were given separate formational numbers on the map (Formations 6 and 7 respectively, Map ). The three hornblendic granodiorite plutons also differ from the Dotted Lake, and Musher Lake Pluton^/ in that they have a relatively high magnetic response. The magnetic response seems to vary directly with the mafic content. The most mafic of the plutons (see Table^°7), the Fourbay Lake Pluton, gives magnetic readings up to 1000 gammas above the background of the surrounding granodiorite gneiss. The less mafic Gowan Lake Pluton gives magnetic intensities up to about 450 gammas, and the least mafic Bullring Lake Pluton intensi ties up to about 200 gammas above similar magnetic backgrounds. As a result the general outlines of the Fourbay Lake and the Gowan Lake Plutons are readily apparent on aeromagnetic maps of the area (Maps 2156G, 2157G, 2158G, and 2168G). The Bullring Lake Piuton is marked on the aeromagnetic maps by an area of slightly higher magnetic response than the surround ing rocks but this is insufficiently distinct to outline the piuton. The Musher Lake and Dotted Lake Flu-Lang, have magnetic responses similar to the adjacent granodiorite gneiss and metasedimentary gneisses. Fourbay Lake Piuton This piuton covers an area of about 24 square miles and is located on the west side of the area, mostly to the east and northeast of Fourbay Lake. The piuton is roughly oval in shape with its long dimension of about 8 miles oriented north-south and its short dimension about 4 miles east-west. The piuton consists of pyroxene-hornblende-biotite granodiorite (see Table lUo,l ) and intrudes biotite granodiorite gneiss of the Black-Pic Batholith. The piuton is poorly exposed over much of its area and contacts exposures were not found. On the north, east and southeast boundaries the contact of the piuton is essentially parallel to the strike of the foliation in the adjacent biotite granodiorite gneiss but on the south the contact appears to cut across the general trend of the gneiss foliation. The most typical rock type of the piuton is usually massive, medium-grained, equigranular with an overall light grey to pink colour which in detail consists of about 80 to 85 percent light grey quartz and feldspar mixed homogeneously a with between 15 and 20 percent dark green to black mafic minerals. Hornblende and biotite are easily recognized in hand specimen and scattered grains of magnetite and epidote are sometimes visible. Scattered pink spots, usually about 1 millimetre in size, and apparently the result of local colouration of potassic feldspar grains are characteristic of the rock. Two modal analyses of the typical rock of the pluton are shown in Table Sample Nos. *r— and The essential constituents are quartz, oligoclase, microcline, hornblende, biotite and augite with accessory magnetite, sphene, apatite and zircon and minor secondary epidote and carbonate. The plagioclase, microcline and quartz grains are anhedral with the microcline occasionally interstitial to the plagioclase. The plagioclase is zoned and micrographic inter- growths of quartz occur in the plagioclase. The microcline is slightly perthitic with small amounts of plagioclase strings and blebs confined largely to the cores of the microcline grains. Augite is not abundant and generally occurs as kernels enclosed by coronas of hornblende. The hornblende is dark green in colour and the biotite dark brown and pleochroic haloes are common in the biotite. The percentage of biotite and hornblende in the rock generally totals about 15 percent but the relative proportions of biotite and hornblende appears to be quite variable. The accessories sphene, magnetite and zircon are generally associated with the biotite in the rock as is the secondary epidote. The apatite is scattered throughout. In some parts of the pluton, particularly on the east and north, the biotite in the granodiorite of the pluton is much more obvious in hand specimen than in the typical rock described above. The biotite is coarser grained and initially it was thought that the biotite was more abundant but modal analyses (Table w,/) of the two samples of *Biotitic augite granodioriteT, formation 6d on Map ?, , Sample Nos. o and, I , indicates that some of these Tbiotitic' rocks have a biotite content similar to the typical rock (compare samples No. J> and / ). The significant feature about these TbiotiticT samples appears to be the coarser grain of the biotite, a slightly higher mafic content and a significantly higher content of clinopyroxene and magnetite. The *biotiticT rock is similar in appearance to the typical rock except for the presence of coarse-grained highly reflecting flakes of biotite. It is interesting to note that on the aeromagnetic maps (maps 2157G and 2158G) the highest magnetic response over the area of the pluton occurs over the areas of tbiotitict rock and this is presumably due to the higher magnetite content of this rock. The rocks of the pluton are usually foliated near the contacts and in these areas contain numerous partly digested xenoliths of hornblende gneiss or amphibolite. These xenoliths are angular to subrounded and usually only a few inches in size. Since there is little or no material equivalent in composition to the xenoliths, in the surrounding granodio rite gneiss of the Black-Pic Batholith, the xenolithic material must have been brought from some other location during intrusion of the pluton or stoped from the now eroded roof of the pluton. Within the main mass the rocks are predominantly massive but occasionally a faint banding due to variation in the mafic content was noted. This feature can be seen in two outcrops on the power line which crosses the pluton. The granodiorite of the pluton is intruded by dikes of leucocratic pegmatite and aplite and by diabase dikes. The pluton is also cut by the &vr<5&& Lake Fault and the granodiorite near the fault is commonly pinker in colour than the typical rock of the pluton. A lineament, which is parallel to the .Swede Lake Fault, crosses the pluton in the north and this may represent another fault but no substantiating information is available. Gowan Lake Pluton Only part of this pluton outcrops in the Black River map area. The entire pluton has not been mapped.but from the aeromagnetic (Maps 2156G, 2157G, and 2168G) and geological A information available (Milne/ I966).the pluton covers an area in excess of 30 square miles and is roughly V-shaped in outline with an oval apophysis on the inside of the eastern limb. The apex of the V-shapet/lies southwest of the Black River area, A apparently from the aeromagnetic map, about 1 mile northeast hUtZS of the Pic River at Highway No. 17- The V-shape*is recumbent to the east so that the west limb extends north-northeast from I the apex through Sprucetop and Veronica Lakes in the Pic River map-area, and the east limb trends east-northeast from the apex through the south end of Gowan Lake and through Valley Lake, in the southwest, corner of the Black River area. The oval apophysis lies on the north side of the east limb, mainly between Harriet and Gowan Lakes. The pluton mainly consists of hornblende-biotite granodiorite or quartz monzonite. The outer southeast and northwest contacts of the V-shaped pluton cut mafic meta volcanic and metasedimentary rocks while the inner contacts of the V-shaped mass and the oval apophysis intrude biotite granodiorite gneiss of the Black-Pic Batholith. The pluton is well exposed in the Pic River map-area and in the Harriet Lake-Gowan Lake region of the Black River area, but exposures are poor between Gowan Lake and the Black River. The contacts are rarely exposed and within the mapped areas the contacts of the pluton are essentially parallel to the foliation in the adjoining country rocks. However, on the west shore near the south end of Gowan Lake a contact between the pluton and biotite granodiorite gneiss is exposed and at this location although the contact of the plut is predominantly parallel to the foliation of the gneiss, periodically the contact makes small, step-like jogs across the foliation of the gneiss. In the Pic River area contacts between the pluton and mafic metavolcanic rocks are exposed and in this area 'TThe intrusive (pluton) interfingers with, and a considerable number of quartz monzonite dikes intrude, the metavolcanic rocks in the contact areas.*1 (Milne/ 1966). The rocks of the Gowan Lake Pluton are generally less mafic (see Table M>,I ) and slightly coarser grained than the rocks of the Fourbay Lake Pluton. Modal analyses of three samples, Sample Nos. ST , °i and 10 , Table /J&J , show a range in composition between granodiorite and quartz monzonite and a wide range in the relative proportions of biotite and hornblende present. The rocks of the Fourbay and Gowan Lake Plutons are similar in colour; the small percentage difference in the mafic content is not noticeable in hand specimen, but the Gowan Lake rocks are medium-vto coarse-grained and are commonly porphyritic. The porphyritic character is not always readily apparent because the phenocrysts of microcline in the rock are generally anhedral and peppered with inclusions of biotite which reduces the contrast between the phenocrysts and the ground mass. The minerals quartz, plagioclase, potassic feldspar, hornblende, biotite, epidote and sphene are usually visible in hand specimens of the Gowan Lake rocks and in the porphyritic specimens pink or grey op 1 anhedral microcline phenocrysts, ranging- to about ^ inch xn t-rta- fir in size, are set in a medium-to coarse-grained^of these minerals. The plagioclase is zoned oligoclase or oligoclase-albite and is generally anhedral but euhedral to subhedral laths are sometimes enclosed in microcline grains. Lobes of myrmikite are frequently present between grains of plagioclase and microcline. The microcline is coarse, anhedral, commonly porphyritic and usually slightly perthitic with a little exsolved string and vein material in the cores of the grains. Other major constituents are quartz, which is anhedral and often interstitial, dark green hornblende and brown biotite. A very amall quantity of clinopyroxene was present in one of the samples examined (Sample No. % , Table /''Js< / ). Accessory minerals include sphene, magnetite, apatite and zircon and secondary epidote, chlorite and sericite is present as alteration of the plagioclase and the epidote and chlorite largely as alteration of the biotite. In sample No. iO , Table W*( , most of the biotite has been altered to chlorite. The rocks of the pluton are generally massive but they may show a poor foliation, especially near the contacts. on In contact with the metavolcanic rocks the intrusive tends to be equigranular, less quartzose and more mafic. In the Pic River area it is common to find amphibolitic xenoliths at the contact between the Gowan Lake Pluton and the biotite granodiorite gneiss of the Black-Pic Batholith similar to those in the Fourbay Lake Pluton. The Gowan Lake Pluton is also intruded by leucocratic aplite dikes and diabase dikes and is cut by a number of faults. Bullring Lake Pluton \ \ \ \ Bullring Lake Pluton Only a small portion of this pluton, covering about 8 square miles, outcrops in the map-area. The mapped area represents a very small part of a large mass, probably of batholithic dimensions, which extends from the Black River, just south of the map boundary, east-southeast across Highways No.614 and No.17, through Cedar and Dune lakes and probably beyond the south end of White Lake. The pluton appears to intrude metasedimentary rocks over most of its known length. There are no exposures of the contact within the map—area but the contact is exposed on Highway No.17 about % mile west of the junction with Highway N0.614. In this location the contact is conformable with the foliation in the adjoining metasedimentary rocks; the hornblende-biotite granodiorite of the pluton is finer grained at the contact and granodiorite and metasedimen tary bands of about 1-foot width are interlayered over about 10 feet from the main contact. Some contorted xenoliths of metasediment are present in the granodiorite and occasional layers of metasediment curve from the contact into the grano diorite. The best exposures of the granodiorite intrusion within the map-area are located at the south end of East Barbara Lake, along Highway No.614 and on the Canadian Pacific Railway spur line from Struthers. The pluton consists essentailly of hornblende-biotite granodiorite and modal analyses of two samples, Sample Nos. // and / 2_ , are shown in Table /U». ) . The granodiorite is massive, coarse-grained and porphyritic. The porphyritic feldspar grains are up to ^ inch in size but, as in the Gowan Lake Pluton, the porphyritic texture is not always apparent immediately because the phenocrysts contain many inclusions of biotite and the feldspar of the rock is uniform in colour. The rock is normally light grey in colour with a mafic content between 5 and 10 percent. The coarse grain size, porphyritic texture and low mafic content render the rock distinctively different from the granodiorite of the Fourbay Lake Pluton and usually the mafic content is noticeably lower than in rocks of the Gowan Lake Pluton. Scattered rounded mafic xenoliths are present in many outcrops throughout the pluton and these are usually less than 3 inches in size. A few irregularly shaped xenoliths of metasedimentary material with dimensions of several feet were noted near the contacts. The granodiorite consists essentially of quartz, oligoclase-albite, microcline, hornblende and biotite and these are visible in most hand specimens. Accessory minerals include sphene, magnetite, apatite and zircon and secondary chlorite; sericite and epidote are usually present, the latter mineral is commonly visible in hand specimens. The oligoclase-albite exhibits oscillatory zoning and subhedral -§aa^" phenocrysts of the plagioclase usually contain inclusions of hornblende and biot'ite which in some grains appear to be arranged in concentric zones around the core. The microcline is frequently intersti tial and a little string perthite is present. The hornblende is dark green and the biotite dark brown with pleochroic haloes , and slight alteration to chlorite is common. Some purple fluorite was noted coating fracture planes in the granodiorite on Highway N0.614 but no fluorite has been observed in the main mass of the rock. The granodiorite is commonly pink to red in colour adjacent to daijbase dikes and fault planes .and epidote and hematite-carbonate veining is also common at these locations. A particularly good exposure of the relationship of the reddening of the granodiorite to faulting occurs in a road cut on Highway No.614 about 1000 feet south of the map limit. The rock in this locality is cut by at least three hematite-carbonate gouge-filled shear planes which are up to 1 foot in width (Photo 7 )• Immediately adjacent to the shear planes the granodiorite is completely altered to a brick red colour and small miarolitic cavities develop in the rock but the original porphyritic massive texture is retained. The plagioclase is albitic and clouded with sericite and dusty alteration products. Dislocation of the grains is indicated by the plagioclase twinning. The microcline is clouded with dusty inclusions along cleavages and fractures but is clearer in comparison with the plagioclase. The biotite is completely and the hornblende partly altered to chlorite. Epidote and carbonate occur throughout the rock and as fracture filling. A few feet away from the shears the granodiorite is less strongly coloured. The rock is flesh pink in colour but is cut by many thin fractures along which the bordering feldspar of the granodiorite has been reddened . (^h-oiSo^Sfc^b^ The feldspars are slightly less altered and the chlorite alteration of the mafic minerals is less with much fresh biotite remaining in the rock. The pjfrj&dtrtg and red fracture veining persists with diminishing intensity up ^ mile to 1 mile away from the fault zone. As mentioned above the same features were noted in the vicinity of some diabase dikes but it is not certain if this is due to the diabase dikes or that the diabase dikes have been intruded along an earlier fault plane. The granodiorite is intruded by diabase dikes and by dikes of pegmatite and aplite. Musher Lake Pluton This pluton underlies an area of about 10 square miles and is roughly tadpole-shaped with the head lying between Musher Lake and Highway No.614 and the tail extending southeast from Musher Lake to the trail between Theresa Lake and Etna Lake. There are very few exposures of the pluton and location of the contact is extremely speculative over much of its length. The pluton is in contact with mafic and acid metavolcanic and pyro- clastic rocks on the north side and metasediments on the south. Outcrops on the west side of the pluton along Highway No,614 consist of hornblende-biotite granodiorite similar to that of the Bullring Lake Pluton. On the east however, the rocks are less mafic, usually light pink-coloured, biotite granodiorite similar to the rocks of the Dotted Lake Pirrfc-o^i which is described in the next chapter. Due to the very limited exposure it was not possible to determine the relationship between the two phases of the pluton. The principal differences between the two phases are indicated by comparison of the modal analyses of the Bullring Lake Pluton samples, Sample Nos.Jf and / 2. , and the Dotted Lake P-i**fea*i sample, Sample No. Lj , Table Wo./. In hand specimen the rocks of the eastern part of the pluton are light coloured, generally pink, equigranular, coarse-grained and massive with biotite the only apparent mafic mineral, while the rocks of the western side are slightly darker, more mafic, grey coloured, coarse-grained, porphyritic and massive with horn blende and biotite both apparent. Just south of the pluton on Highway No.614 the meta- sedimentary gneiss has been intensely crenulated and almost converted to a muscovite schist and on the north side of the pluton the pyroclastic and aei-d metavolcanic rocks in the region 1 of the Von Klein Property also contain a great deal of muscovite. It is possible that the development of the muscovite in these rocks and the crenulation is related to the intrusion of the pluton. Also on the north side of this pluton the pyroclastic and metavolcanic rocks just east of Summers Lake have been fractured into large blocks which are cemented together by granitic material. It is uncertain whether this brecciation is related to faulting or to the effects of intrusion of the Musher Lake Pluton. Dotted Lake Batholith The full extent of this batholith is unknown but about 90 square miles of it outcrops in the southeastern part of the map-area. The batholith intrudes rocks of the mafic metavolcanic formation and biotite granodiorite gneiss of the Black-Pic Batholith. Peninsulas of the mafic metavolcanic formation project into the interior of the Dotted Lake Batholith and some of these are almost separated from the main mass of metavolcanic rock to become roof pendants. Dilation produced by intrusion of the Dotted Lake Batholith is suggested by the presence of thin layers of mafic, metavolcanic rock at the contact between this batholith and the biotite granodiorite gneiss of the Black-Pic Batholith, and these may be up to I2 miles from the main mafic metavolcanic mass. Exposures of the contact are rare but good exposures can be found on the southwest side of Dead Otter Lake at the end of the access road and just south of the shore towards the firetower trail. No inhomogeneity was noted in the main mass of the Dotted Lake Batholith which appears to consist throughout of f&uc o~~ 1 rnnnnrntiin-hi ntitr granodiorite. The typical rock is light pink to white in colour, massive, coarse-grained and inequigra- nular with about 3 percent mafic minerals. Biotite is the only mafic mineral visible in hand specimen with quartz and feldspar and occasionally epidote. The granodiorite is intrusive into the mafic metavolcanic rocks with sharp contacts and generally the granodiorite in the contact area is slightly finer grained and darker in colour than in the main mass of granodiorite. Between Roger and Olga lakes the mafic metavolcanic rocks are almost isolated as a roof pendant and are probably present as a very thin veneer over the granodiorite. The rocks in this area are essentially migmatites composed of mafic metavolcanic and aplitic material. > In the contact areas the granodiorite is invariably sheared and the shearing generally parallels the contact and the foliation in the bordering country rock. The shearing produces a foliation so that the rock around the Batholith contact is essentially a granodiorite gneiss and in the area north of the mafic metavolcanic rocks, north of Dotted Lake, this is sometimes difficult to distinguish from the granodiorite gneiss of the Black-Pic Batholith. However, the sheared gneiss of the Dotted Lake Batholith is generally pink, tends to develop porphyroblas^" tic feldspars and is less mafic than the grey, equigranular gneiss of the Black-Pic Batholith. Foliation is also developed in the main mass of the batholith adjacent to shear zones. An example of this can be seen at the north end of Theresa Lake where a steep, west-dipping foliation is developed in the granodiorite adjacent to a 3-foot wide mylonitic zone in the granodiorite. The foliation is marked by the orientationof biotite in the granodiorite and by the squashing and elongation of quartz grains. Another example occurs about 1 mile north of ThEresa Lake. In this location the shear zone is not exposed but the granodiorite is strongly foliated, trending roughly east-west and dipping at a shallow angle to the north, suggesting that there may be some low angle thrust faulting in the area. On the west side of White Lake in the southeast corner of the area, the metavolcanic and metasedimentary formations are intruded by a great deal of amphibolitic metagabbro, hornblende- biotite granodiorite similar to the Gowan Lake Pluton material, and mafic hybrid granodiorites or diorites derived by contamination of the granodiorite by mafic metavolcanic and metagabbroic material. Agmatites composed of amphibolitic metagabbro frag ments cemented by hornblendic granodiorite are very common in the area from Etna Lake southeast to Highway No.17. Between Tri Lake and White Lake a thin band of foliated hornblende- biotite granodiorite lies between the mafic metavolcanic forma tion and the leucogranodiorite of the Dotted Lake Batholith. This band appears to be continuous with the hornblendic grano- diorites and hybrid phases on the northwest and southwest shores of White Lake. No contacts are exposed between the leucograno diorite and the hornblendic granodiorite and its hybrid phases so that the relationship between them is uncertain. Some mafic hornblendic granodiorites or diorites also occur within the Dotted Lake Batholith north of Roger Lake and the relationship here is also unknown. Many of the hybrid granodiorites and diorites are foliated and the mafic content is extremely variable. Some of the less mafic phases resemble the hornblende- biotite granodiorite gneiss of the Manitouwadge area (page i. — ) which is older than the biotite granodiorite gneiss of the Black-Pic Batholith. However, the massive hornblendic grano diorite phases in the White Lake area seem to be related to the younger Gowan Lake granodiorite indicating a similar young age for the hybrid rocks of the White Lake area. It seems probable that any of the granodiorite intrusive phases in the area may have been contaminated by mafic metavolcanic or metagabbroic material thereby producing mafic hornblendic hybrid phases. Since the compositions of these intrusiv-es are not vastly 1 Fragmental plutonic rock with more or less granitic cement. (AGI Glossary, Supplement, I960, p. 1 ) >c different, separation of the respective hybrids on a lithological basis would be very difficult. The modal analysis of a typical leucogranodiorite from the Dotted Lake Batholith is shown in Table "6,1, Sample No. 1^ . The essential constituents are quartz.sodic oligoclase, microcline, biotite and minor hornblende. Accessory sphene is present and a little secondary epidote is associated with the biotite and plagioclase. The grains are anhedral, inequigranular but usually coarse except for the accessory sphene which is fine grained and euhedral. The plagioclase is most commonly coarse ns grained, shows normal zoning and frequently exhibits myrm^kitic lobes adjoining microcline grains. The microcline is generally coarse and some grains appear to include some of the smaller oligoclase grains, while others appear to be interstitial to the plagioclase and quartz. The quartz grains are irregular in shape, coarse, and usually slightly strained. The biotite is dark brown, the hornblende dark green and the epidote is present as a dusty alteration in the cores of some plagioclase grains and associated with some of the biotite grains. The Dotted Lake leucogranodiorite is cut by a few thin scattered dikes of pegmatite and aplite and occasional quartz veins. Quartz veins are rare in the main mass of the batholith but in the area around Dead Otter Lake quartz veining is abundant. A possible explanation of the quartz vein distribution is that the leucogranodiorite in the Dead Otter Lake area is intruded into an anticlinal fold in the mafic metavolcanic formation and the quartz veins are concentrated in the crestal area of the » intrusi^ee. None of the veins examined contained visible mineralization. A few dikes of fine-grained hornblende grano- diorite intrude the leucogranodiorite in the Spider Lake area and numerous diabase dikes also cut the batholith. Silicic Dikes There are a large number and variety of intrusive silicic dikes and stocks in the area and for most of thsse it is difficult to show a direct relationship to any of the large plutons or batholiths. It is probable that early and late intrusive dikes are associated with each of the granitic plutons and batholiths in the area and many of these dikes from different sources could have similar compositions. It is not possible with the limited outcrop and the scale of mapping to separate all these. The widest variety in type of dike intrusive occurs in the mafic metavolcanic formation but quantitatively there is more intrusive dike material in the metasedimentary formation. The granodioritic plutons and batholiths are intruded by silicic dikes but in the younger of these, the tLate Silicic Int-rusi-v-e Rocks1, the dikes are few in number and almost entirely pegmatite and aplite. Dark grey feldspar (hornblende) porphyry dikes appear to be among the oldest silicic dikes in the area. Most exposures of this type of dike were found intruding the mafic and dacitic pillow lavas and pyroclastic formations along the C.P.R. spur line between Amwri Lake and Pinegrove Lake. On fresh surfaces these rocks are dark grey in colour, medium-/to fine-grained with ?*r white porphyritic feldspar grains wngimggup to 4 millimetres in size. The rock may be massive or foliated. Small hornblende phenocrysts are usually scattered among the feldspar phenocrysts and in some dikes these predominate. Individual dikes may be inhomogeneous having predominantly feldspar phenocrysts in one part and dominantly hornblende phenocrysts in another and less frequently parts of the dike are essentially non-porphyritic. The rock consists of quartz, calcic oligoclase, hornblende and biotite with accessory apatite and pyrite. The plagioclase and biotite are usually altered and secondary minerals include epidote, chlorite, carbonate and sericite. The plagioclase phenocrysts are euhedral to anhedral and many are zoned, often with oscillatory zoning. These dikes are intruded by light grey feldspar porphyry dikes and fine-grained, dark green syenodiorite dikes. Light grey feldspar porphyry dikes are found throughout C the mafic metavolcanic and pyrq^lastic formations in the area. Good exposures of this type of dike are found along the C.P.R. track in the same general area as the dark grey porphyry dikes. The light grey porphyry dikes are light grey to pink in colour massive to foliated, with a fine-grained quartzo-feldspathic matrix containing short dark biotitic danhffls and densely packed with light buff to white anhedral to euhedral feldspar pheno crysts up to 5 millimetres in size. These dikes are readily distinguishable from the dark grey porphyry dikes even when direct comparison is not possible as on the C.P.R. railway track. The light grey to pink colour is distinctive reflecting a lower mafic content, the phenocrysts are generally more abundant and exclusively feldspar, and hornblende is absent. The light grey porphyries consist essentially of quartz, oligoclase-albite, microcline, and biotite with accessory sphene, magnetite, pyrite and apatite. Both the microcline and plagioclase form phenocrysts and some of the plagioclase grains are slightly zoned. Altera tion of the plagioclase and biotite is common and secondary epidote, chlorite, and sericite are present. The coarser phases of the light grey porphyry resemble some of the medium to coarse-grained biotite granodiorite dikes, and the marginal phases of the biotite granodiorite of the Dotted Lake Batholith tend to be porphyritic and resemble the light grey porphyry. It seems probably that the light grey porphyry dikes are related to the biotite granodiorite of the batholith. A great many biotite granodiorite or granite dikes intrude the metavolcanic, pyroclastic and metasedimentary formations and the biotite granodiorite gneiss of the Black-Pic Batholith. These are generally white, light grey or pink in colour, they may be foliated or massive and vary in grain size from fine-grained to coarse-grained. These dikes are biotitic with a mafic content usually less than 10 percent and are probably related to the late silicxc plutonic intrusives xn the area but it is not possible, as stated above, to relate individual dikes to specific plutons. A small number of very fine-grained, dark green, mafic hornblendic dikes were found in the area. This type of dike was found in the C.P.R. railway cuts in the vicinity of Jenny Creek intruding metavolcanic rocks and dark grey feldspar porphyry dikes and also on the west side of No.6 Lake intru ding biotite granodiorite gneiss and biotite granodiorite dike rocks. These dikes were mapped initially as lamprophyre but in the No.6 Lake location they appeared to be associated with a coarser grained dark to light grey porphyritic (hornblende ) syenodiorite. Thin section examination indicates that the fine grained dark green dike rock consists of oligoclase-albite plagioclase, microciine, and hornblende with accessory sphene and pyrite and secondary biotite and chlorite alteration of the hornblende. The mafics total between 20 and 30 percent. The rock composition would thus appear to be syenodioritic. The porphyritic syenodiorite is composed essentially of the same zoned oligoclase, microciine and hornblende but has appreciably more biotite. The hornblende occurs as coarse grained phenocrysts in a fine-grained matrix of plagioclase and microciine. The biotite is present as long thin laths replacing the coarse hornblende grains and confined almost entirely to the hornblnede grains. Accessory sphene, zircon and apatite are plentiful and magnetite and secondary epidote are also present. The mafic content of the porphyritic phase is about 20 percent but the rock is much lighter in colour than the fine grained phase because of the porphyritic character of the mafics. All the dikes described above are apparently older than white to pink coloured, massive, fine-to medium-grained leucogranitic dikes which, for example, intrude the granodiorite gneisses around the junction of Highway No.614 and the C.P.R. track just south of Manitouwadge, and intrude the gneisses and other dike rocks exposed on the west side of No.6 Lake. These leucogranitic dikes contain between 2 to 5 percent fine-grained biotite peppered throughout the rock and quartz and plagioclase are also visible in hand specimen. Pegmatite and aplite dikes intrude the above leuco granitic dikes, the granodiorite gneiss of the Black-Pic Batholith and all the late silicic plutons and batholiths. It is probably that pegmatitic and aplitic phases are associated with several of the large intrusive plutonic masses in the area and Pye (1957) indicates at least two ages of pegmatite-aplite dikes. Relatively few pegmatite and aplite dikes occur in the late silicic plutonic intrusive masses and they are not very plentiful over much of the Black-Pic Batholith but in the northern part of the batholith between Manitouwadge, Gaffhook Lake and Twist Lake pegmatite and aplite dikes are abundant. The pegmatite and aplite may be white or pink in colour and single dikes may contain both white and pink rock. Pegmatites of similar appearance cut each other and cut aplites, and, likewise, aplites cut aplites and pegmatites, and single dikes were observed composed of both aplite and pegmatite. In some dikes the aplite and pegmatite material occur in layers parallel to the contacts and in others pegmatitic grains of feldspar and quartz are isolated in aplitic material. In some pegmatites the co[r/a!se—grained pertitic microcline feldspars are oriented perpendicular to the dike contacts and some of these are wedge- shaped, enlarging inwards from the dike contacts. These feldspar a.re grains range up to 9 inches in length. Good exposures of the pegmatites are found on the Ontario Paper Company road south of Morley Lake and along the Macutagon River just south of Gertrude Township. Many of the pegmatites and aplites are biotitic but the mafic content is usually less than 5 percent. No economically interesting minerals were noted in these dikes. A small number of other silicic intrusive bodies were found in the area. Among these are hybridized granodiorite, sheared muscovite dikes and augite syenite dikes. Two small bodies of the granodiorite were mapped, one an irregular, branching dike over 10 feet wide cutting mafic metavolcanic material on the west side of Highway No.614? just south of Summers Lake, and the other a small piug ©£ about 300 feet \n diameter containing much mafic material and intruding the mafic metavolcanic rocks about ^ mile east of Highway No.614 and 2000 feet north of Summers Lake. The rock contains about 30 percent mafic minerals and consists essentially of quartz, zoned oligoclase-andesine, microcline, hornblende and biotite with accessory sphene. Sericite, epidote and chlorite alteration products of the plagioclase and biotite are also present. The muscovite dikes were found only in the vicinity of the Von Klein Property east of Summers Lake. These rocks may be confused quite easily with the muscovitic metasedimentary and metarhyolitic gneisses in this region but they are distinguishable and chilled intrusive contacts were found on these dikes. The rock is medium-to coarse-grained and light grey to pearly white in colour. The rock may be massive but more commonly it is sheared into a strongly foliated rock with coarse Tquartz eyeT augen developed. Quartz,feldspar and muscovite are the only minerals apparent in hand specimen. In thin section the essential constituents were identified as quartz, albite and muscovite but in some parts of the dikes the albite seems to be completely replaced by muscovite, leaving only quartz and muscovite. A little pyrite is disseminated in the rock and minor chlorite is also present. Most of the muscovite in these dikes appears to have developed by replace ment and the original composition of these dikes is unknown. The augite syenite dikes were found intruding the porphyritic pillowed dacites on the east side of Pinegrove Lake and intruding the granodiorite gneiss just north of the Swede Lake Fault, west of Barehead Creek. The rock is often quite distinctive on weathered surface being pink with coarse, dark green hornblende spots. The fresh rock is grey to mauve in colour, fine-grained with medium-to coarse-grained euhedral to subhedral hornblende crystals densely, scattered throughout. The mafic content is between 15 and 20 percent. In thin section it was found that the phenocrysts consisted of augite clino- pyroxene rimmed or completely altered to green hornblende. These were set in a groundmass of highly altered, zoned albitic plagioclase and microcline with secondary epidote and greenish mica. Some dikes of similar appearjn/ajce but of finer grain and containing only hornblende were found cutting the Dotted Lake Batholith in the Spider Lake region and it is possible that these are the same type of dikes with no remnant pyroxene. These dikes are probably related to the Fourbay Lake Pluton but it is also possible that they relate to the Port Coldwell Alkalic Complex in the Marathon area. Diabase BifeeH There are many diabase dikes in the area and they intrude all the formations previously discussed in this report. The dikes are usually vertical to steeply dipping and although the strike attitudes of the dikes vary locally there are ^he *H*rce major strike trends. The dikes tend to strike approximately northwest, north-south or N35°E. The northwest-trending dikes seem to be the most consistent in attitude whereas there appears to be a range of attitudes between north-south and N35°E and examination of the dikes on the west side of White Lake suggests the possibility that some of the north-south trending dikes actually emanate from the N35°E dikes. Some of the larger northwest-trending and N35°E-trending dikes are apparent on O.D.H. - &.$.C* fnapf i aeromagnetic maps of the area (2156G, 2157G, 2158G, 2167G, 2168G and 2169G) as elongated magnetic ridges, particularly in the areas of granitic rocks. Some of these^however^are not apparent and there is usually little indication of the north- south dikes. Dikes have been traced within the area for more than 10 miles and aeromagnetic information suggests that they may extend for hundreds of miles. Widths of the dikes vary from a few inches to about 500 feet. Most of the diabase dikes are very similar in appearance. The typical rock is dark grey, medium-grained, equigranular, and massive, with characteristic diabasic texture. At dike contacts the diabase is invariably chilled to a black aphanitic rock containing a few scattered fine-grained phenocrysts of plagio- clase and clinopyroxene. In some of the wider dikes the interior parts are coarse-grained and mottled light greenish-grey and black in colour. In a few of the wider dikes, for example, the dike intruding the north end of the Fourbay Lake Pluton, irregular patches of red, granophyric, feldspar-rich diabase are present in the interior of the dike. Disseminated pyrite and pyrrhotite are very common accessories in the diabase and the rock weathers a very distinctive rusty brown to buff colour which makes it stand, out from the other rock types in the area. A few of the dikes in the area contain coarse, rounded to euhedral, yellowish phenocrysts of altered plagioclase up to 1 inch in size. These phenocrysts are not present throughout the entire dike so that one dike may in ^art be porphyritic and in part non-porphyritic. However, the few porphyritic dikes encountered all seemed to belong to the northwesterly-trending group so that in mapping a distinction was made between the porphyritic and non-porphyritic types. Essentially the diabase consists of felted mass of zoned, labradorite feldspar laths with interstitial augite. Quartz and granophyric material is present interstitially in all the diabases, porphyritic and non-porphyritic, examined under the microscope and is particularly evident in the coarse-grained phases of the diles. Accessory minerals include magnetite, ilmenite, pyrite and pyrrhotite. Secondary hornblende and uralite are major alteration products of the pyroxene with minor biotite and chlorite. The plagioclase is invariably altered extensively to sericite. All the dikes in the area would appear to be quartz diabase. A porphyritic (plagioclase) diabase dike in the vicinity of Cedar Lake,about 3 miles south of the map-area, has been dated by a Whole Rock, K-Ar analysis as 2320 million years old (Wanless et al, 1965). Another Whole Rock, K-Ar age determination on a diabase dike on Highway No.17 just north of Jackfish Bay, Lake Superior, and about 40 miles west of the map area, indicated an age for the dike of 1810 million years (Wanless et al, 1965). It is probable that among the many diabase dikes in the area there are several ages of dikes, However, since these are similar in appearance, are generally quartz diabases, and since the porphyritic texture is not a consistent feature in dikes showing this texture, it is unlikely that different ages of dikes can be separated in the field. It has been proposed (Fahrig et al, 1963) that in the Canadian Shield dikes of a particular age occur in swarms which conform generally to a particular strike direction and this appears to be a reasonable generalization. However, there are p(o/£bably sufficient exceptions to the generalization to prevent the application of an age to a specific dike solely on the basis of the dike attitude. In the Pic River area (Milne, I966) there are at least two X-shaped dikes, one with limbs trending north-south and northeast, and the other with limbs trending north-northeast and northwest, and in the present map- area there is a suggestion that some north-south dikes emanate from the northeast-trending dike on the west side of White Lake. Dikes in the Pic River and Black River map-areas generally conform to joint directions in the country rocks. Some of the dikes—;in-^hese—^o_.aneas_may„_coji£oxm^ country rocks. Some of the dikes in these two areas may conform predominantly to one joint direction in a particular location but the contact in fact zigyzags utilizing two joint directions in the country rocks, and it is conceivable that at some point along these dikes the emphasis may change from one joint direction to the other. One further difficulty in determining the age of a specific dike from its attitude is that although dike attitudes seem to be fairly consistent in granitic areas, in areas of metavolcanic rocks,for instance, where the structura trend of the metavolcanic formations is in the quadrant between northwest and northeast (see Pic River map-area, Milne, 1966), the diabase dikes tend to conform to the structural trends rather than to the jointing, and dikes may curve and vary from northwest to northeast. The diabase dikes are undoubtedly younger than all the fag C£t^7 6 S-/JZO other conoolidatred rocks in the area and dikes were found intruding all of the formations with the exception of the serpentinized peridotite bodies. The same feature was found in the Pic River area. The absence of dikes in the serpentinite is probably due to the non-friable character of the rock. Pleistocene and Recent Most of the Black River area is covered by glacial drift material and this seems to be of three principal types, which are: (l) glaciolacustrine sediments (varved clays and beach sands and gravels), (2) glaciofluvial sediments (sand and gravel esker ridges, and (3) glacial moraine. Thick deposits of the glaciolacustrine material appear to have the greatest areal extent within the map—area, underlying the wide Black and Macutagon River valleys and their tributary creeks and underlying the drainage areas of the Nama and Fourbay Creeks. The remainder of the area is generally higher with good rock exposure and only thin drift cover, usually bouldery clayey sand. Varved clays are exposed in the lower parts of the river banks along much of the Black and Macutagon Rivers and in the banks of Mobert, Barehead, Fourbay and Nama Creeks, around Agonzon Lake and occasionally along the C.P.R. railway tracks. The varves generally range in thickness from less than 4 inch to 1 inch but in one exposure on the Black River the total thickness of a light and dark layer was about 6 inches. In most of the sections examined the varves were exposed in the lower part of the river or creek bank and the total thickness of clay exposed rarely exceeded 10 feet. In some locations the varved clays have filled depressions between rock outcrops. An example of this can be seen on the C.P.R. railway track just north of the Ontario Department of Highways road maintainance camp. The railroad cuts expose varved clays and granodiorite gneiss in low ridges of about the same height. Throughout most of the river and creek valley areas the surface is sandy and in the river bank sections the varved clays are always overlain by bedded sands. The exposed thick nesses of the sands varies from 30 to 50 feet. The sands may grade down through silty and clayey sands into the varved clays, but in some sections the varved clay is overlain directly by coarse sand beds, with interspersed 1-foot thick pebble bands, and this in turn is overlain by well bedded fine-grained sands. The pebble bands are densely packed with well rounded pebbles, most of which are less than 1 inch in diameter. A few well rounded pebbles, generally less than 1 inch -d-iamotor but in a Sam eft *" ranging up to 22 inches, are usually scattered around on the A sandy surface of the ground and these pebbles are often of /tntes/py? C varieties of coralline or other limestone.-k^ny-Wi*.. Gravel is generally of minor importance in the glacio- lacustrine material but on Highway No.614, between the Ontario Department of Highways camp and No.6 Lake, a beach spit or bar containing a considerable amount of gravel, extends southwards from a high outcrop area south of Barehead Lake. The deposit is probably a bar rather than a spit as it is bounded on the east and south by varved clays exposed along the C.P.R. tracks, on the west and south by varved clays exposed in Barehead Creek, and on the north, between the bar and the Barehead Lake outcrop area, a depression just south of No.6 Lake is probably floored by clays and silts. Highway No.614 follows the top of the bar while the C.P.R. railway track follows the east base of the bar and is over a hundred feet below the level of the road. In the surfacd^ qaa-i^rires along Highway No.614 no bedding is apparent in the sedimentswhich consist of coarse sand and gravel and are relatively unsorted except for the absence of very fine and very coarse material. Pebbles and boulders are rounded to subrounded with the largest being about 1 foot in diameter and the majority about 1 inch in diameter. On the east side of the highway an excellent vertical section through the bar is exposed in a railway gravel quopry, serviced by a short spur line, about 7000 feet south of No.6 Lake. The west face of the quar-py xs over 100 feet high and is composed of well bedded e coarse sands and gravels. Some of the beds are graded with coarse sand at the base of the beds and pebbles up to 2 inch diameter in the upper part of the beds. The coarsest gravel beds occur near the top of the €fu-a-*»**y- face where there is 4 to 5 feet of gravels containing pebbles up to 6 inches in diameter. The beds trend approximately N30°E, roughly parallel to the elongation of the bar, and dip southeasterly towards the varved clays on railway tracks at about 3®°• A number of esker-like sand and gravel ridges occur in the area, mostly on the east side of the Black and Macutagon River valleys. Examples can be seen paralleling Twist Lake and some of the lakes between Twist Lake and the Macutagon River. Others occur paralleling the string of lakes just north of the mafic metavolcanic formation in the Dotted Lake region and another occurs about 1 mile west of Pinegrove Lake. These ridges tend to border the glaciolacustrine deposits flooring the Black and Macutagon River valleys and thereby parallel the borders of high outcrop area which rise above these deposits. Thus in Twist Lake aid Pinegrove Lake regions the ridges trend north- south to northeast, while in the region north of Dotted Lake the ridges trend nearly eastwest. Most of these ridges have A the sinuous and acute form of eskers and trapped kettle lakes are associated with them. They would therefore appear to be of glaciofluvial origin, and—pjaesumafoi-y—would—fre—older—than t^e^gXa-e-are3rarctxstT-±rre--"deposit-s. Some of the more rounded ridges might possibly be beach bars since they occur where o. the lacustrine clays and sands shelve off the outcrpp areas. The mafic metavolcanic formation in the south of the map-area has resisted erosion to a greater extent than the neighbouring rocks and as a result it forms high ridges standing above the general level of its surroundings. These mafic metavolcanic ridges are generally mantled by a thin cover of glacial till material consisting of brown clayey sand containing many large angular boulders. This type of material is exposed in pits along the Dead Otter Lake road. Similar material forms hummocky ridges in the area between Kaginu and Morley Lakes. These ridges are composed of many large angular boulders up to 5 feet in diameter in light ;ociEE2E§h^brown sandy clay. The ridges do not appear to have any particular form and probably represent till material dumped from a melting ice sheet. A thin cover of the same type of material covers much of the higher outcrop regions in the map-area. Throughout the area glacial striations range between S2QOw and S40°W indicating a general ice movement southwards at about S30°W. This is similar to the predominant direction of ice movement in the Pic River area (Milne, 196 ). As stated previously varved clays and sands are exposed in the Fourbay and Nama Creek valleys. The deposits in these areas are an extension of glaciolacustrine deposits filling the valley of the Pic River, and are similar to the Black River deposits. It has been pointed out by W.R. Farrand that "These quiet water sediments required high water levels in the lake Superior basin so that the Pic-White Otter system was drowned for a distance of more than 50 miles above its present mouth. The northernmost exposure of varves in the Pic area is 56 miles straingtline distance from the mouth of the A t- Pic and occurs at 1040-1050 feet above sea level." Thus the Pic and Black River varved clay deposits represent sedimentary deposition in the ria shoreline area of a large glacial lake which formerly occupied the Lake Superior basin. Recent materials are accumulating in swamps and lakes in the area. In addition the migratory nature of the Black and Macutagon River channels is evident from the meandering character of these rivers and the associated ox-bow lakes. Examination of air photographs, particularly in the area between Dotted Lake and Agonzon Lake, reveals the presence of numerous gullies bounded by levees within the Black River valley indicating that the surface sands and clays have been reworked by the river wandering about the valley floor. Structural Geology Folding The metavolcanic, pyroclastic and metasedimentary rocks of the Black River area have been highly metamorphosed and have undergone intense complex folding. Distinctive marker horizons are absent in the main fold areas and the number of reliable top determinations that could be made was very small*However on the basis of the information available it is possible to make a simple generalized interpretation. Top determinations were obtained from pillow structures and the few reliable observations recorded are restricted to the mafic metavolcanic formation southwest of Dead Otter Lake where south facings are indicated. There do not appear to be •fro, .be any major breaks between the metavolcanic, pyroclastic and metasedimentary formations. Southwards the mafic meta volcanic flows appear to be interbedded with the pyroclastic material which in turn grades southwards into the metasedimentary formation. It seems reasonable to infer from these few top determinations and the gradational relationships that these formations ave- younging- southward-s and represent a relatively uninterrupted depositional sequence beginning with mafic vulcanism which terminated with less extensive extrusion of acid and pyroclastic material succeeded finally by clastic sedimentation. The widening of the mafic metavolcanic formation between Highway No. 614 and Ravine Lake is interpreted as being Ik, The syncline northwest of Dotted Lake is less readily apparent than the anticlinal fold. No distinct lithological bands can be traced around the syncline and the axial trace shown on the map is *®3*y approximate. The presence of the fold is inferred from a change in dips from the north to south, northwest of Dotted Lake, and from minor folds northeast and northwest of Dotted Lake^ These minor folds are located near the north boundary of the mafic metavolcanic formation and indicate a syncline to the south. A //-diagram of the strike and dip attitudes northwest of Dotted Lake, indicates a possible fold axis trending S60°W and plunging between 40° and 60° southwest. Plunges measured directly from the minor folds vary between 23° and 85° southwest. The Dead Otter Lake anticline and Dotted Lake syncline have similar axial trends and plunges. Similarly trending folds on a slightly smaller scale are also indicated in the metavolcanic rocks between Roger Lake and Olga Lake. A west-plunging anticline and parallel syncline appear to be combined in a S-shaped drag fold on the east side of Roger Lake and#//-diagrams of these folds (*ii^ir-SS5lf4- indicated axial trends of about S75°W plunging between 15° and 20° west. These plunge are much shallower than in the folds west of Dead Otter Lake. Rocks of the metasedimentary formation are poorly exposed. In most exposures the foliation due .to orientation f/a£e$ of biotite g¥»spjk%8- in the rocks is parallel to the original bedding lamination but in at least two areas the bedding and foliation are not parallel. In conglomerate exposures on the trail between Theresa Lake and Etna Lake the foliation, marked by elongation of pebbles and orientation of biotite gsjaaaas., cuts across the bedding at an acute angle and the attitudes suggest that the exposures occur on the north side of a west- plunging synclinal fold trending approximately S75°W and plunging 40° west. Folding is also implied in the area south of Solong Lake by an outcrop on the south shore of the lake in which the pebble bands of conglomerate are cross cut at a steep angle by the fLaliatJrGii, Within the map-area visible folding of the metasedimentary beds was observed in only two outcrops, one on Highway No. 614 just north of East Barbara Lake and one on the west shore of East Barbara Lake at the north end. In these outcrops the style of folding is essentially similar and tightly isoclinal, slightly overturned to the south. Cleavage is developed parallel to the axial plane, paralleling the bedding on the fold limbs and cross- cutting on the noses of the folds. Excellent exposures of folds in the metasedimentary formation occur on Highway No. 17 about 4 miles south of the map^area, between the Highway No. 614 junction and Cigar Lake. A These exposures indicate that the metasediments have been subjected to intense shear folding which has produced tightly isoclinal, symmetrical similar folds. Cleavage is well developed in these folds and cuts across the metasedimentary bedding in the noses of the folds but the noses represent a very small part of the fold so that in most of the exposures the cleavage is parallel to the bedding. The mafic metavolcanic rocks are not strongly foliated and in particular around the hinges of folds the foliation is poorly developed. In most outcrops the foliation can be termed a gneissosity but locally, where mica is present, it becomes a schistosity. As far as can be determined the foliation has developed parallel to the original banding on the limbs of folds and this also seems to be true around the crest of the fold just west of Dead Otter Lake. However, in the area about 7000 feet north of No. 3 Lake the foliation appears to have developed at an acute angle to the original bedding. A few small scale folds were recognized in areas Usujefcett" of mafic metavolcanic rocks and in most of these the banding is folded into tight, similar folds with a cleavage developed parallel to the axial plane indicating that these are essentially shear slip folds, (r^'fc M>,//J Stretching and shearing have been quite severe, as witnessed by the stxi&aMp^rmit of pillows and agglomerate fragmentSjbut in general this shearing does not appear to have V/ est of been as intense around the crest of the major fold c^e^sad^n- Dead Otter Lake as on the limbs. Lineation marked by orientation of hornblende grains is developed in the mafic metavolcanic rocks and small scale folds and crenulations are sometimes exposed. A density plot of the plunge attitudes of all the lineations and small scale folds observed in the mafic metavolcanic and pyroclastic-acid metavolcanic formations was made on an equal area Schmidt Net (^^p^?^^,) and this indicates that there are two plunge maxima (1) S40°W, 47°SW. and (2) S24°E, 70°SE. Few plunge determinations could be made in the area of metasediments. On the Etna Lake trail the foliation and bedding attitudes indicate a westward plunge of about 40° but in the middle of the metasedimentary area around Highway No. 6l4j the plunges appear to be very gentle, ranging up to 10° east and west As noted above there are two major directions of lineation and drag fold plunge in the area. One of these, S40°W, 47°SW, is essentially parallel to the plunge directions of the folds described above. The presence of a second major plunge direction trending S24°E, 70°SE, at a steep angle to the plunge of the major folds, and the gently undulated east-west plunge of minor folds in the metasediments on Highway No. 6li+3 north of East Barbara Lake, suggested that the area had been affected by a second stage of folding. Examination of the regional structure however, reveals the following:- 1. The country rocks around the mapped portion of the Black-Pic Batholith all dip off the batholith, 2. Fold structures in the country rocks either plunge away from or parallel to the adjacent batholith contact^ 3. fioughly parallel fold trends occur in the Pic River (Milne, 196 }, Black River, and Manitouwadge (Pye, 1957) areas but the axial trend of the most intense folding is not the same in all these areas. For example, in the Black River area and the Manitouwadge area the axes of the major, more intensely folded folds, trend between east-west and southwest-northeast, approximately parallel to the batholith contacts in these areas, while in the Pic River area, where the batholith contact trends northerly, the more tightly folded folds trend roughly north-northeast, and the southwest-northeast trending folds are much more open. Thus the axis of most intense folding in the country rocks around the Black-Pic Batholith roughly parallels the adjacent batholith contact while the more gentle cross-folding plunges away from and trends at a steep angle to the batholith contact. 4. The Black-Pic Batholith appears to have a domical form (page S~f ) with essentially flat-dipping foliation near the centre of the mass. The foliation in the centre is %? With in fact gently undulated i-nt-o- flat-dipping open folds trending southwest-northeast and southeast-northwest (JSJg^fel).. These facts indicate that a genetic relationship exists between the folding of the country rocks and the form and folding of the Black-Pic Batholith. The two fold trends in the country rocks adjacent to the batholith must be contemporaneous since in a specific area the most intense folding is parallel to either one of the fold trends depending upon which one is more nearly parallel to the batholith contact in that area. The rocks of the Black River area are interpreted as lying on the south flank of an anticlinorium with the rocks of the.Manitouwadge area lying on the north flank, and the granodiorite gneiss of the Black-Pic Batholith occupying the core (See Fig7^*s&). Southwards from the Black River area it is believed by the writer that the metasedimentary rocks form a synclinorium, thus the mafic metavolcanic rocks which are known to outcrop south of Highway No. 17 are probably equivalent to the mafic metavolcanic rocks in the Black River area. The ductile fold behaviour of the country rocks, their high grade of metamorphism and the form of the Black-Pic Batholith (page S"? ) indicates that the intrusion of the granodiorite gneiss and the folding took place under deep to o seated catazonal conditions. The younger granodiorite-quartz monzonite plutons of Fourbay Lake, Gowan Lake, Bullring Lake, Musher Lake and Dotted Lake have produced minor secondary modifications of the folding. These later plutons have caused dilation of the country rocks. For example the Musher Lake Pluton appears to produce a sharp bend in the metasediments in the vicinity of Highway No. 614, and north of Dotted Lake the granodiorite has pried a thin band of mafic metavolcanic rocks away from the main mass. Intrusion of the younger plutons has been controlled to some extent by the earlier folding and by the contacts between mafic metavolcanic and quartzo-feldspathic gneisses. The V-shape of the Gowan Lake Pluton is essentially conformable to the country rock structure and the Dotted Lake Batholith conforms largely to the Dotted Lake anticlinal fold. Shearing is common at the contacts of the younger intrusive masses and is very apparent at the contacts of the Dotted Lake Batholith. A Crenulation, minor drag folding, muscovitic alteration and contact metamorphic effects may be present at the contacts of the younger plutons. However, the dominant country rock structures appear to have originated in association with the syntectonic intrusion of the Black-Pic Batholith. Faulting Outcrop evidence of faulting is very limited, marker horizons are rare, and the effects of folding are not always clear due to the limited outcrop in many parts of the area but a number of major faults have been interpreted and minor faulting is undoubtedly present. Minor faulting is well displayed in the band of muscovitic quartz-feldspar gneiss east of the Black River where there are three sets of faults, a dextral set trending N65°W, a sinWitral set trending N15°E and a set of strike faults parallel to the gneiss foliation. These faults show displacements varying between a few inches and a few feet. Similar small shear faults were found at a few locations in the mafic metavolcanic rocks, and examples can be seen at the south end of Theresa Lake. Major Faults Bullring Lake Fault Hematite-carbonate gouge filled shear planes of this fault outcrop on Highway No. 614 about 1000 feet south of the map boundary. In the outcrop the fault cuts granodiorite of the Bullring Lake Pluton and red hematitic alteration of the granodiorite extends outwards for up to half a mile on either side of the fault. The fault strikes approximately N60°W, cross-cutting the metasedimentary and metavolcanic formations in the vicinity of the Black River and can be traced west- northwestwards to a small lake about 6000 feet north of Gowan Lake where the granodiorite of the Gowan Lake Pluton is stained hematitic red and cut by a stockwork of small barren quartz veins. A small right hand offset along the fault is suggested by the mafic metavolcanic band west of the Black River and this would conform with the small scale faulting noted in the muscovitic quartz-feldspar gneiss just 1 mile northeast of the fault. However outcrop is very poor in this area due to the extensive Pleistocene deposits. Phil Lake Fault This fault strikes almost parallel to the Bullring Lake Fault trending N65°W. The presence of the fault is inferred from the presence of a lineament observed on aerial photographs and indications of a right-hand offset in the mafic metavolcanic band on the west side of Phil Lake. The fault seems to terminate against the Jenny Creek Fault in the east and disappears under thick drift cover to the west. Pinegrove Lake Fault„ This fault is one of the most extensive in the area. It trends N50°W and extends., at least3 from Pinegrove Lake in the east•northwestwards through Swede Lake and the Fourbay Lake Pluton to beyond the west limit of the map sheet. The fault is apparent on aerial photographs as a strong lineament which extends northwestwards well beyond the map-area. Indications of the fault in outcrop are seen northeast of Fourbay Lake at the north end of Lineal Lake and in the small lakes to the east. In these areas the granodiorite gneiss of the Black-Pic Batholith and the granodiorite of the Fourbay Lake Pluton are extensively reddened and cut by red vein alteration. In addition the mafic metavolcanic rocks at the north end of Pinegrove Lake are fractured and sheared and in the vicinity of the junction of Barehead Creek with the Black River a projection of the mafic metavolcanic formation has undergone a right hand strike separatidn of about 6000 feet. The Pinegrove Lake Fault joz appears to continue on the east side of the Jenny Creek Fault producing right-handed offset of the pyroclastic-acid metavolcanic formation just east of Summers Lake. Jenny Creek Fault This fault crosscuts the metavolcanica pyroclastic and metasedimentary formations. Where the fault cuts the metavolcanic formation it trends roughly north-south but the trend swings to south-southwest where it cuts the metasediments. The fault parallels Jenny Creek which lies in a well-defined lineament. The lineament more or less forms a pass through the area of high mafic metavolcanic ridges and has been utilized in the contruction of Highway No. 614. The presence of the fault is indicated by the juxtaposition of the acid metavolcanic and mafic metavolcanic rocks on opposite sides of Highway No. 614 in the vicinity of Pinegrove Lake3 by the apparent offset of the pyroclastic-acid metavolcanic formation in the vicinity of Phil Lake' and by the fracturing and hematitic and epidotic alteration of the mafic metavolcanic and granitic dikes in the railroad cuts north of Phil Lake. To the north and south the fault disappears beneath thick drift cover. A south-southwest trending fault3 similar in trend to the south part of the Jenny Creek Fault has been interpreted about halfway between Pinegrove Lake and the Black River. The presence of this fault is inferred from the presence of a lineament observeable on aerial photographs and from the interpretation of outcrop and aeromagnetic information (see O.D.M.-£.-;•<-. aeromagnetic map 216BG). 10 + White Lake Fault This fault is apparent as a lineament on air photographs and trends southwest across the northwest corner of White Lake. Faulting is inferred from the abrupt termination of the mafic metavolcanic formation at the lineament and a sharp swing in the gneissic foliation. J^r the southwest, between Etna Lake and Buie Lake the fault plane appears to be occupied by a wide diabase dike. This diabase may occupy the fault plane to the ca. northwest also but there are no exposures. In the south part of the area two other small faults have been postulated, one just east of No. 3 Lake and one on the /fk north side of Dotted Lake. East of No. 3 Lake a fault is believed to lie in a north-northeast trending gully. The pyroclastic-acid metavolcanic formation contacts swing sharply or are offset in the vicinity of the gully and some mafic metavolcanic flows interbedded with the pyroclastic rocks appear to terminate at the gully. Geophysical investigations (p*P>M, A ile No. 63.169$) on the von Klein Property suggest that other small faults may be' present in this region. On the north side o.p.rf. - GS>C* of Dotted Lake aeromagnetic information (map 2168G) suggests that the mafic metavolcanic rocks are faulted and outcrop distribution in the region tends to support this. However outcrop in the region is very poor and there are no apparent lineaments so that location of the fault is very speculative. There are a number of diabase dikes in the area and the attitude of the inferred fault is based on the assumption that the diabase dikes tend to follow a major fracture direction in the region. A number of lineaments are indicated in the map-area and many of these are in the areas of granodiorite gneiss. It was not possible to determine if these lineaments represented faults, due to the reconnaissance nature of the mapping and absence of marker horizons in these areas. One small fault has been interpreted in the northeast corner of the map-area paralleling No. 5 Lake. This fault is postulated on the basis of the foliation attitude in the locality, the sheared and fractured nature and widespread red hematitic alteration of the granodiorite gneiss. Some shear zones are indicated in the biotite granodiorite north^and east of Theresa Lake. In these shear zones the normally massive granodiorite is strongly foliated and occasionally mylonitic and it is possible that some of these shears actually represent large faults -wMe-hr•&•*"f wu.uld I'tiquix'c detailed mapping to/trace ttrgmr* Examining the regional fault distribution it is apparent that the Pinegrove Lake Fault is essentially parallel to the major northwest-trending Runnalls Lake Fault in the Pic River area (Milne, 196 ) and the Mose Lake Fault in the Manitouwadge area (Pye, 1957) and in unmapped areas very extensive northwest- trending lineaments are relatively common. The west-northwest trend of the Bullring Lake and Phil Lake Faults is similar to the trend of the Fallen Lake, Veronica Lake and Sprucetop Lake Faults of the Pic River area and although this trend is close to that of the northwest faults it seems to represent a different, less extensive fault set. Extending the comparison of the /o Black River area faults with other faults in the region^ the Jenny Creek Fault may relate to the north-south trending Cadawaja, Clinger and Fox Creek Faults and the White Lake Fault to the northeast-trending Nama Creek Fault of the Manitouwadge area. Information in the Black River area is not sufficient to determine the relative ages of these different fault sets but information from the Manitouwadge area (Pye, 1957) and the very persistent nature of the northwest-trending faults suggest that these may be the youngest in the region. Diabase dikes appear to haveAutilised many of the fault planes. /*> Economic Geology Introduction Until recently probQecting in the area has been very limited but over the last few years the similarity of the rock formations, and its proximity, to the Manitouwadge mining camp and the potential mining area around Marathon, has brought it increasing attention and at the present time much of the southern part of the area is covered by staking. A certain amount of assessment work, including geological and geophysical reports and diamond drillhole logs, has been submitted to the Ontario Department of Mines. Reports are on file at Toronto in the Mining Lands Branch office, and reports and drill logs are filed with the resident geologist in Port Arthur. The company names,type of information, year reported and file number are listed below. Company Name Year Type of Information File No. Mclntyre Porcupine Mines Ltd. 1963 Geological Survey 63-1210 Geophysical Survey 63-1210 Drilling Port Arthur Carravelle Mines Ltd. 1965 Geological and 63.E6 Geophysical Interpretation 1966 Geophysical Survey 63-I698 Irish Copper Mines Ltd. I966 Geophysical Survey 63-1716 T ^ 108 Stratigraphic Considerations in Mineral Exploration In the Pic River, Manitouwadge and Black River areas the predominantly pillowed character of the metavolcanic rocks and well bedded nature of the tuffs attest to their accumulation under subaqueous conditions, and their association with essentially metagreywacke-type sediments is characteristic of a eugeosynclinal depositional environment. Mapping at the present time is insufficiently complete to permit direct correlation of the different formations but it is probable that there is more than one period of mafic vulcanism represented in the region and possibly there is repetition of a number of volcanic- sedimentary depQsifcional cycles. i?or- exuuiple, i'Ax- rriafM.c metavolcanic formation in the Pic River area appears to be underlain by a pyroclastic-silicic metavolcanic formation (Milne 196 ) whereas the mafic metavolcanic formations in the Manitouwadge (Pye 1957) and Black River areas are overlain by metasedimentary and pyroclastic- silicic metavolcanic formations- On the basis of the presently known structure it is believed by the writer that the Manitouwadge and Black River formations are essentially equivalent in age and belong to a single volcanic- sedimentary cycle. The biotite-quartz-feldspar paragneisses and mafic metavolcanic rocks of the Black River area are similar in appearance and composition to the metasedimentary and metavolcanic rocks in the Manitouwadge area. There are differences however. Unlike the Manitouwadge area iron formation is relatively rare in the Black River area, conglomerates are present in the lower section of the metasedimentary formation, and a pyroclastic-silicic metavol canic formation occurs between the mafic and metavolcanic and 109 metasedimentary formations. These differences are believed by the author to be due to facies changes and to the restrict ion of the mafor centres of volcanic extrusion to the south ern region between Marathon and White Lake. In the Black River area, the pyroclastic-acid metavol- canic farmation is of limited extent east-west, and it grades into metasedimentary material to the west so that the mafic metavolcanic formation in the -eastern and western parts of the area abuts the metasedimentary formation. It is believed that the pyroclastic-silicic metavolcanic formation is simi larly restricted in the north-south direction so that in the Manitouwadge area the metasediments lie directly upon the ma fic metavolcanic formation. In all probability the base of the metalogically to the base of the similar formation in the Man itouwadge area. Sedimentary material may have accumulated in the Manitouwadge area at a time of waning mafic volcanism and during expulsion of silicic volcanic and pyroclastic material and general absence of volcanic material in the wide belt north of Manitouwadge may not be due solely to deep downfolding of the volcanic material beneath the metasediments, but may be largely due to the thinning and disappearance of the volcanic material to the north. The relative scarcity of iron formation in the Black River area, compared with Manitouwadge, may be due to the fact that conditions for accumulation have been more unsettled in the no. immediate vicinity of the sources of volcanic extrusion, and possibly to the coarse clastic type of sedimentation occurring in the Black River area as indicated by the presence of conglomerates. Th-e—p-r-es-ette-e—o-f—appr"eTT±abie—strlphrd-es—in—t he- Black—River^±r'orr^o"rmatTo f acn-es-^irf-f^r'eirge^^ the.qp and the ^-an-v^mf-a^ge -djz&¥r-~£omia1?to¥irr> The little iron formation found in the Black River area is in part banded magnetite-quartz but abundant pyrite and pyrrhotite are present and the iron formation is in part slaty. The iron formation occurrences on the yon Klein Property appear to be very local features and in one occurrence the thin iron formation appears to be underlain by tuff and overlain by a thin mafic flow which is interbedded in the predominantly pyroclastic formation. The sulphides in the iron formation may be replacement material but it is possible that sulphide facies iron formation is present. The iron formation in the Manitouwadge area (Pye 1957) is metamorphosed to banded magnetite-amphibole-quartz and garnet-amphibole-epidote-magnetite- quartz mineral assemblages and these mineral facies tend to indicate that the original iron formation belonged essentially to the oxide and iron silicate facies (James 1955)• The occurrence of oxide and iron silicate facies of iron formation in a predominantly sedimentary rock formation, as at Manitouwadge, and of the banded magnetite and sulphide facies with volcanic formations is typical of the eugeosynclinal Algoma Type iron formation (Gross 1965). In the Manitouwadge area the copper-zinc-lead orebodies /// are generally associated with muscovite-quartz schists, and iron formation or related rocks (Pye 1957). They seem to occur near the same stratigraphic level within t he metasedimentary formation and comparing these orebodies with similar types in other areas (McAllister 1959; Hutchinson 1965; Roscoe 1965; Richards 1966; Vokes 1966) it is possible that they are of an age and origin similar to the rocks in which they occur. Age determinations on the Manitouwadge orebodies (Davis et al 1965) and on the neighbouring metasediments (Lowdon 1961) indicate that these have similar metamorphic ages. Iron formation and muscovitic schists are present in the contemporaneous metavol- canic-metasedimentary formations in the Black River area and it is possible therefore that similar sulphide bodies are also present. Descriptions of Mineral Showings Fairservice Occurrence (l) A zinc occurrence was discovered in 1957 by B. Fairservice of Manitouwadge who operates the trap line in the Dotted Lake-Mobert Creek area. The occurrence is located in mafic metavolcanic rocks about 400 feet east of the old lumber company dam on the north arm of Dotted Lake. There are a number of small pits scattered around the area in rusty zones in the volcanic rocks and in white porphyritic (quartz and feldspar) dikes which contain disseminated pyrite. At the main occurrence there is a shallow pit about 4 feet square with two other smaller pits about 5 and 10 feet to the west. A leucocratic //:> porphyry (quartz, feldspar) dike strikes N70°E across the south end of the main pit and about 22 feet north of the dike a rusty, horizontally striated, shear plane trends N70°E through mafic metavolcanic hornblende gneiss and dips about 8l°S. Between the shear plane and the porphyry dike and* north of the shear plane for about 2 feet the rock is a very coarse-grained rusty weathering garnetiferous amphibolite containing much disseminated magnetite and light coloured amphibole. North of the shear zone the garnetiferous rock grades into the normal dark green medium-grained hornblende gneiss of the area. On the south side of the shear plane and within 1 foot of it, 3 to 4 irregular stringers of massive black sphalerite up to 1 inch in thickness, trend roughly parallel to the shear plane. The sphalerite stringers disappear quickly to the east and west. They are absent in the small pit about 10 feet west of the main pit and were not seen in outcrops just east of the pit. About 50 feet east of the main pit the garnetiferous material thins to about I2 feet, and about 75 feet east of the pit both the garnetiferous material and the shear plane peter out into rusty, typical metavolcanic hornblende gneiss cut by a few thin rusty quartz stringers. Except for a little disseminated pyrite in the mafic metavolcanic rocks and leucocratic porphyry dikes no other mineralization was observed in the surrounding rocks. n the spring of 1965 about 170 claims were staked covering the Fairservice occurrence and most of the metavolcanic d rocks north and west of Dotte^ Lake. These claims were optioned to Irish Copper Mines Ltd. and in May 1965 an electromagnetic and magnetometer survey was flown over the claim area. The /n. electromagnetic survey indicated one good conductor and a few very minor conductors but none over the zinc showing loca tion. Ground checking of the airgeophysical survey was carried out by the company in the late summer of 1965- Kusins Occurrence (2) A lead-zinc occurrence was discovered by R. and W. Kusins in I963 as a result of geochemical soil sampling. The occurrence is about 1500 feet north and 3000 feet west of the mouth of Amwri Creek at the Black River. It can be reached by a poorly marked trail starting on the west side of the Black River opposite the mouth of the creek about 4500 feet north of Amwri Creek. The occurrence is on the northwest side of a low ridge and occurs in mafic metavolcanic laminated hornblende gneiss which is bounded on the southeast by siliceous and migmatitic meta- sedimentary or metapyroclastic material and on the northwest by hornblende-biotite granodiorite of the Gowan Lake Pluton. It is believed by the writer that a major west-northwest trending fault lies about 1000 feet south of the showing (see Map No. and 0/?St->/-t''e i/c & In I964 T. and W. Kusins held five claims in the area, Nos. T.B.104950 to 104954 inclusive, and the occurrence is just within claim T.B.104951 about 650 feet south of the No.4 post. At the time the occurrence was examined there were four pits and a plan of these is shown in Pisrtre M>j<. The countryrock around the pits is mafic metavolcanic, laminated hornblende gneiss. Pits Nos. 1, 2 and 3 expose a rusty gossan zone about 1-foot thick, overlying a rusty, silicified pyritic zone up to 6 feet wide which parallels the foliation of the country rock, trending N55°E and dipping about 50°NW. The three pits cover a strike length of about 100 feet. The pyritic silicified zone was not found in outcrops a short distance east of the No.3 pit and west of the No.l pit the zone disappears beneath a swamp. The light grey to white silicified zone contains disseminated pyrite throughout and in addition seams of massive pyrite up to 8 inches thick parallel the trend of the zone. Thin seams of massive pyrite, about l/8 inch thick, a±s=» These cress cis fftf'^f /*yni'?e cross+cut the silicified zone and the wide pyrite searns,th-at strike about N65°W, and this is parallel to a major ^oint direction in the surrounding country rocks. In parts of pits Nos. 2 and 3 disseminated galena and sphalerite are mixed with the disseminated pyrite. A grab sample taken from the No.2 pit by T. and ¥. Kusins and submitted to the Laboratory Branch, Ontario Department of Mines contained 1.93 per cent zinc, 0.94 per cent lead, 0.64 ozs. per ton silver, and traces of copper and gold. The No.4 pit is about 65 feet south of the other three and exposes a second zone, about 22 feet wide, composed of quartzo-feldspathic sericitic schist with 1/16 inch pyrite layers paralleling the foliation of the schist. No galena or sphalerite were observed in this pit. As stated previously a major fault trending N65°W is believed to be about 1000 feet south of the occurrence. Near the occurrence the metavolcanics are fractured. In an outcrop about 60 feet south of the No.l pit the metavolcanic rock is cut by a zone of brecciated metavolcanic material striking N70°W and about 150 feet south and slightly west of the pit the metavolcanic rocks are highly fractured and the fractures filled with carbonate and occasionally minor galena. The mineraliza tion in the area may be related to faulting, however, as was stated above, the main pyrite seams and silicified zone are cross-cut by thin possibly remobilized, pyrite seams which trend N65 W parallel to the main fault and joint direction in the country rock. This suggests that the silicified zones and main pyrite seams originated before the fracturing. This showing was examined in 1963 by geologists of The Mining Corporation of Canada Ltd. and Willroy Mines Ltd. before trenching was done and the disseminated sphalerite- galena found. The showing was later examined in 1965 by geologists of The Consolidated Mining and Smelting Company of Canada Ltd. (now Cominco Ltd.). i/^on Klein Occurrences (3) A number of occurrences of copper-nickel and copper- lead-zinc mineralization were found in the area east and south east of No.3 Lake by C. Von Klein and in 1962 a block of 52 claims enclosing these occurrences was optioned to Mclntyre Porcupine Mines Ltd. At the time the property was examined by Mclntyre Procupine Mines Ltd. there were four main occurrences. A geological map of the claim area was prepared by the mining company in 1962 and the occurrences numbered from 1 to 4. The same system of numbering is used in the following descriptions. II (e Occurrence No. 1 This occurrence is located on the south side of the Dead Otter Lake road about 2 mile east of No.3 Lake, on a roughly east-west stretch of road (see rSste "'3 ). A pit has been blasted in the outcrop. The mineralization consists of pyrite with minor chalcopyrite and pyrrhotite disseminated in a coarse-grained dark green amphibolite4 a^d==b^laBq5s==€«P*ih« N^.^^gr<5u-p="^iien:tijaja^^ . The amphibolite is in contact to the south with a siliceous garnetiferous gneiss exhibiting thin contorted lamination and containing small, and possibly rotated, mafic inclusions. -Cc/ The mineralizafedban amphibolite is invaded by stringers of quartzo-feldspathic material emanating from the siliceous gneiss and although very little of the contact is exposed the mineral ized amphibolite is thought to be an extra large inclusion rafted in the siliceous gneiss which is probably welded tuff material. A chip sample over a 2-foot section submitted for assay by E.G. Pye, Resident Geologist, Ontario Department of Mines, Port Arthur indicated a content of 0.42 per cent copper and 0.18 per cent nickel. Occurrence No. 2 ^his occurrence, sometimes referred to as the main occurrence, is exposed 1000 feet south and 300 feet east of the No.l occurrence. Mineralization here appears to be similar to that in the No.l Occurrence. Pyrite,chalcopyrite and pyrrhotite are disseminated in a large irregularly shaped mass of coarse-grained, dark green amphibolite which is in contact with a rhyolite breccia at the only place where the contact is exposed. Exposures are limited but the amphibolite is interpreted by the writer as a large block rafted in a rhyolite breccia plug. The matrix of the rhyolite breccia is faintly foliated, very fine-grained and light pink in colour with abundant silvery flecks of muscovite throughout, and consists of muscovite, quartz and alkalic feldspar with minor biotite, chlorite, apatite and epidote. The matrix cements together a great many angular, mafic, hornblendic fragments and rhyolite blocks and the breccia is intruded by younger granitic dikes (Photo Two, 2-foot section, chip samples were taken from this occurrence by E.G. Pye, Resident Geologist, Port Arthur, and assayed 0.33 and 0.31 per cent copper and 0.17 and 0.41 per cent nickel sra ^ciCr-tM^ x Occurrence No. 3 This occurrence is about 350 feet south of No.3 Lake and 4 mile west of the Dead Otter Lake road. Mineralization consists of finely disseminated pyrite and pyrrhotite with a trace of chalcopyrite in a rusty shear zone about 22 feet wide in a biotitic quartzite or metagreywacke containing thin mafic hornblende layers. The shear zone is essentially parallel to the foliation in the country rock, striking N65 E and dipping about 80°N. A strike length of about 15 feet is exposed and the shear seems to die out at the west end. The mineralization is similar to that seen in the silicified zones in Kusins m occurrence. No assays are available on this material. Occurrence No. 4 This occurrence is in the mafic metavolcanic rocks just north of the contact with the pyroclastic-acid metavolcanic rocks, and about 850 feet west and 300 feet north of the No.l occurrence. Mineralization occurs as thin irregular stringers containing pyrite, pyrrhotite and chalcopyrite with occasional sphalerite and galena in a zone of fractured mafic metavolcanic rock about 5 feet wide. The fracture zone trends roughly east-west and dips about 85°S. While examining this showing another small pit was found on the north side of a small creek, about 250 feet east and 160 feet north, in similarly fractured and mineralized mafic metavolcanic rocks. J)$& -<~^.—---^ A Horizontal Loop E-M and Magnetometer ground geophy U sical survey was carried out by Mclntyre Procupine Mines Ltd., also in 1962, and six electromagnetic conductive zones were outlined. These are shown on «Pi£r,fc.eA/0 ^ . Four of these were A weak conductors and the other two<>^aefi'6&—en*d—r=a, were of moderate strength. Zones A and B seem to be at the contacts of "thin mafic flows within the predominantly pyroclastic-a-e-ird metavolcanic rocks and zone C at the main contact between the latter rocks and mafic metavolcanic rocks. The remaining zones all seem to be within the mafic metavolcanic rocks. Zones B and C were trenched (•^Piafcs®' ^and £"), and the results of assayed samples from these trenches are shown in &a&3*e "*?-tf6;', //? Mclntyre Porcupine Mines Ltd. drilled 28 diamond- drill holes. Most of this drilling was concentrated around occurrences No.2 and 4 while the electromagnetic conductive zones were investigated with a few very short holes. The drilling indicated that there was no immediate downward extension of the mineralization at occurrences No.l and 2. Drilling on occurrence No.4 indicated continued weak mineralization at depth with a second weakly mineralized copper-zinc zone a short distance north of the main zone, and a short hole drilled on conducting Zone F indicated a narrow pyrite-pyrrhotite minera lized zone with traces of chalcopyrite. No further work was done by Mclntyre Porcupine Mines Ltd. and the option on the claims was dropped. In 1963 C. von Klein did some further prospecting in the area and located two additional mineralized occurrences. •^he exact location of these showings is not known but it is believed that the small pit found while examining occurrence No.4 (page/^') is the No.5 showing mentioned in the 'Report on the Pulfa Group of Claims' by V.Wierzbicki (File N0.63.E6). In I964 Carravelle Mines Ltd. gained control of a large block of claims designated as the Pulfa Group consisting originally of 134 claims but later increased to 274 claims, and including the von Klein claims and a large number of claims to the east and west. C. von Klein carried out further prospecting in the area during the summer of 1964 for the company and in August I964 T. Garczynski collected soil and water samples for geochemical analysis. In November I964 a preliminary evaluation 12.0> based on photogeological, geophysical and all other available information (File N0.63.E6) recommended that an airborne geophysical survey be made of the claim group. In July, I965 an airborne magnetometer and Induced Pulse Transient (input) electromagnetic survey was flown over the area. The results of 0. &. /y • this survey (File No.63.1693) indicated several well defined A groups of electromagnetic anomalies, trending essentially parallel to the country rock structure, and generally within the pyroclastic-acid metavolcanic rocks or the mafic metavolcanic rocks immediately adjacent to them. These anomalous zones did not occur over the four main occurrences examined by Mclntyre Porcupine Mines Ltd. It was concluded that these groups of anomalies were potentially more interesting than the main surface occurrences and that they should be further investigated. Geological mapping, ground geophysical surveys and drilling were recommended. In April, 1966 Carravelle Mines Ltd. announced (Carravelle Mines Ltd. Annual Report I965) that an agreement had been made with Falconbridge Nickel Mines Ltd. to carry out zj f - further work on the property. ;/ -' o^*-*'' "-^^""^ During mapping of the area a number of other small \ 1 .'A'?** 1 ,.-«' mineralized occurrences were located but the majority of these .^)>- -•-''rl,''-i( f appeared to contain only pyrite. Most of these consist of narrow, rusty, pyritic shear zones in mafic metavolcanic rocks most commonly striking parallel to the foliation in the country rock. Examples of this type can be seen around the shores of Theresa Lake, on the firetower trail from Dead Otter Lake and on the east side of the Dead Otter Lake road about a mile '£/ northwards from the von Klein No.l occurrence. One band of extensive pyrite mineralization which is not of this type is exposed over a distance of about 9^000 feet between the Black River and the Amwri Lake road, west of No.2 Lake. The pyrite occurs as disseminations, streaks and small lenses in a distinctive band of quartzo-feldspathic muscovite paragneiss in contact with a band of pillowed mafic metavolcanic rocks to the north. It is believed that some drilling was done in 1962 on this pyritic gneiss just south of the Amwri Lake road but no information is available. Two other occurrences were found which are—o-f*-*th*e* No. 2 group—d-escrib ed—in—~the,~int r odu:c1fi~5*n""( pa g eT^™-)-.—-Tlxese ife«o-&c«u.i,reB&es resemble the von Klein No.l and 2 occurrences in that the host rock is similar but they occur in quite different environments. One of these occurrences is in a railroad cut at the north end of East Barbara Lake and appears to consist entirely of abundant pyrite disseminated throughout a coarse grained, dark green, amphibolitic metagabbro sheet intruding the metasedimentary country rock. The second occurrence is in a road cut on the Ontario Paper Company road about 2 mile northeast of Morely Lake. The host rock is a coarse-grained, biotitic, amphibolitic metagabbro, presumably isolated in the granodiorite gneiss of the Black-Pic Batholith, however the amphibolite outcrop is the only one for a considerable distance and no contacts were seen. The metagabbro is cut in outcrop by several thin mineralized fractures containing pyrite but in loose blocks of this material blasted from the outcrop for road IL2L fill small pods of almost massive sulphides occurred in the amphibolite adjacent to the fractures. These pods were up to 4 inches in diameter and contained pyrite, pyrrhotite and chalcopyrite. A trace of an entirely different type of mineraliza tion was noted in an outcrop of garnetiferous metagabbro located on the Ontario Paper Company road about 1^ miles east of the south end of Agonzon Lake. This metagabbro is intruded by the granodiorite gneiss of the Black-Pic Batholith and is cut by late, rusty weathering fractures. The fractures are coated with very minute cubes of pyrite and widely disseminated very fine molybdenite grains. This was the only location within the area where molybdenite was observed. r\ & The mineralized showings in the Black River area seem to fall into three main groups^ (1) mineralization occurring in shear and fracture zones in mafic metavolcanic rocks and sometimes containing minor zinc, lead-zinc or copper-lead-zinc values in addition to pyrite3 (2) mineral ization occurring as stringers^ pods or disseminations in massive amphibolitic metagabbro and sometimes containing significant copper-nickel values in addition to pyrite3 and (3) strata-bound disseminations and stringers of pyrite in muscovite-quartz-feldspar gneiss. The Fairservice and Kusins showings and the mineralized shear zones around Theresa Lake /e-3 belong to the No. 1 group while both the No. 1 and No. 2 types are found on the von Klein Property. The mineralization northeast of Morley Lake and at the north end of East Barbara Lake is of the No. 2 type. Investigations on the von Klein Property have indicated that the amphibolite type copper-nickel mineralization (No. 2 type above) is restricted to the amphibolite which occurs as small isolated blocks, and the Morley Lake and East Barbara Lake also appear to be quife local. However the fact that sulphide mineralization is present in the same rock type in at least three different environments; isolated in a rhyolite breccia, rafted in the granodiorite gneiss of the Black-Pic Batholith and intruding the metasedimentary gneiss, suggests that the mineralization in the amphibolite may be syngenetic. Therefore the masses of intrusive amphibolitic metagabbro in the area may be worthy of detailed study. The No. 1 type mineralized fracture and shear zones contain minor amounts of economically interesting minerals. It is possible that the anomalous electro-vmagnetic zones outlined by Carravelle Mines Limited are related to this type since both the anomalies and the shear and fracture zones trend parallel to the rock formations and occur near the contacts between mafic metavolcanic flows and pyroclastic rocks. Some of the anomalies are quite extensive and therefore may contain significantly more valuable mineralization. The No. 3 type of occurrence in the Black River area contained only pyrite where examined but of the three types it occurs in an environment most closely resembling that of the Manitouwadge ore bodies. The mineralization occurs in a horizon of muscovite, quartzo-feldspathic metasediment very similar lithologically to the muscovite-quartz schists of the Manitouwadge area. This mineralization extends over a considerable strike length, much of it unexposed, and on the basis of its similarity to Manitouwadge occurrences, detailed examination would seem to be justified. /x :> Sc tc c. f'r J &c 'fc rv >< cc S •B-ibl- iogr.aph.y- Bartley, M. W. and Page, T. W. 1957: A geological report on the Hemlo Area, Thunder Bay District, Ontario; Department of Industrial Development, Canadian Pacific Railway. Davis, G. L., Tilton, G. R., Aldrich, L. T., Hart, S. R., and Steiger, R. H. 1965: Geochronology and Isotope^Geology; Annual Report of the Directi-e«- Geophysical Laboratory (1964-1965), Carnegie Institution pp. 165-171'. Fahrig, W. F. and Wanless, R. K. 1963: Age Significance of Diabase Dyke swarms of the Canadian Shield: Nature, Vol. 200, No. 4910, 934. Farrand, ¥. R. 196 : Former Shorelines in Western and Northern Lake Superior Basing University of Michigan Ph.D., Mic. 60-6866. University Microfilms Inc., Ann Arbor, Michigan. Fyffe, W. S., Turner, F. J. and Verhoogen, J. 1959: Metamorphic Reactions and Metamorphic Facies} Geological Society of America. Memoir 73- Gross, G.A. 1965: Geology of Iron Deposits in Canada, Vol. 1 General Geology and Evaluation of Iron Depositsj Geol&g-i-e-a-i Survey o# Canada, Economic Geolog'y Report No. 22. Hutchinson, R. W. 1965: Genesis of Canadian Massive Sulphides Reconsidered by Comparison to Cyprus Deposits; Canadian Mining and Metallur gical Bulletin. Vol. 5$, No. 64I, pp. 236- 300. James, H. L. 1955: Zones of Regional Metamorphism in the Precambrian of Northern Michigan; Bull. of the Geological Society of America Vol. 66, No. 12, Pt. 1, pp. 1455-14SS. Lowdon, J. A. 1961: Age Determinations by the Geological Survey of Canada Report 2. Isotopic Agesj Geol.egieai Survey—o£ Canada. Paper 6l-17v p. 607 "^ > > McAllister, A. L. I960: Massive Sulphide Deposits in New Brunswick*, Canadian Mining and Metallurgical Bulletin,Vol. 63, pp. 50-60. Milne, V. G. 1964: Geology of the Flanders Lake Area: Ontario Depajrtmo-nt, e£ Mines Geologioa-l Repeat, No. 21. J 196 : Geology of the Cirrus Lake-Bamoos Lake Area. Ontario Departflie-ftt. ef Mines, Gee/. (2cpf- Pye, E. G. 1957: Geology of the Manitouwadge Areaj Ontario Department, of Mines, Afm-uai—R-eport. Vol. 66, ft. 8. (.PobUWcd i^feo). Richards, S. M. 1966: The Banded Iron Formations at Broken Hill, Australia and their relationship to the Lead-Zinc Orebodies;Economic Geology, Vol. 61, pp. 72-96. Roscoe, S. M. 1965: Geochemical and Isotopic Studies, Noranda and Matagami Areas: The Canadian Mining and Metallurgical Bull.. Vol. 58, No. 641, pp. 965-971. ' Thomson, J. .E. -.—ID ^isVricT o£ (hunger DA.y ^ 1931: Geology of the Heron Bay Area^A Ontario Depa^fefaent. ef Mines, Aagu^l-ReporI, Vol. 40. ft. 2, pp. 21-39. 1932: Geology of the Heron Bay-White Lake Area; Ontario Department.-e€ Mines, A-nnua-1 Repopfes^ Vol; 41, H. 6, pp. 34-47. {.?M;$^d ^'53). /?/ Wanless, R. K., Stevens, R. D., Lachanche, G. R,, and Rimsaite, R. Y. H. 1965: Age Determinations and Geological Studies, Pt. 1 - Isotopic Ages, Report 5 J Geol&gi-eair- Survoy o£ Canada, Paper 64-17 (Pt. 1). ft* 4/e. 2. s* TO -BUck fioer- fl^<\. \&> 33- I i:(t> •1*r V£ / -/•••' ••• Tr*ib 31 «0 V «*-• tfH/t4*J#4-f>Y'-X* 4 Vitpa. *~(jf$ -forty »J<»^UI*NU ^„- /.?3 # 778. 10+9S* TT-S- *0<+?« fit _ froo. CH. - 6*»e* t1o*Troci f* Jk 3cAt'sf'w/jL*/-f'f><.) /A*W'M «/W^ kornkl'K<(< • «•/«. Hco I" = l&S-r' ^ 3 3 w /« w 3 o o 1 ft I I I 1 d <* 3 1 t 1 1 1 1 5 V "V. 3 ^ i I c5 • v5 N vX <2 1 ? 1 3 D' <0 0» 7 ^ 5 3.? a 6^° v. c o ft >*> o "5 "57 v I V >5 4 1? ft SI N 5 A. s A. A 5 A. 1 & 1 <0 4J£ * 4 "* X V) ^ «- k ONTARIO DEPARTMENT OF MINES PRELIMINARY GEOLOGICAL MAP No. P. 332 BLACK RIVER AREA NORTHWEST PART DISTRICT OF THUNDER BAY Scale 1 inch to ½ mile N.T.S. Reference: 42D/16, 42E/1 , 42C./13, 42F/4 G.S.C.-O.D.M. Aeromagnetic Maps: 2157C, 215SG, 2163C, 2169c. LEGEND FOR P. 332 - P. 335 PHANEROZOIC CENOZOIC PLEISTOCENE AND RECENT Varved clay, silty sand, sand and gravel Unconformity PRECAMBRIAN MARGINAL MOTES PROTEROZOIC KEWEENAWAN Introduction: The area lies between latitudes 48°45' and 49°07' and longi• tudes 85º32' and 86°05' in the District of Thunder Bay. The eastern limit 8a - Diabase (dikes) of the area follows the west boundaries of Bryant, Atikameg and McGill 8b - Porphyritic diabase (dikes) townships and the west limit is marked by the east boundary of Township 75 and corresponds to the east boundaries of preliminary maps Nos. P. 233 and Intrusive Contact P.235. Highway No. 614 to Manitouwadje runs north-south through the centre of the area and the southern limit of the map is about 4 miles north of the ARCHEAN junction between this highway and Trans Canada Highway No. 17. The northern POST-TECTONIC CRANITIC ROCKS limit of the area corresponds to the southern limit of the Manitouwadge Area Map No. 1957-8. 7a - Biotite granite 7b - Biotite granite (dikes) The Black River meanders roughly south-southwest through the 7c - Feldspar porphyry (dikes) centre of the area and lies in a relatively wide low valley floored by 7d - Leucocratic biotite granite (dikes) thick deposits of glaciolacustrine varved clays and silty sands with coarse 7e - Aplite and pegmatite (dikes) sands and minor gravels. The rocks underlying the area west of the Black 7f - Muscovite granite (dikes) River and north of Mobert Creek are predominantly granitic. These granites 7g - Lamprophyre are well exposed and high bare ridges are common. The trend of these 7h - Hematitized, albitized granite ridges is controlled by the gneissosity and jointing and northeast-southwest 7k - Xenolithic granite trending valleys have been accentuated by glacial scouring. In the Black River 6a - Hornblende-biotite quartz monzonite valley, Nama Creek valley, Wabikoba Lake and south White Lake areas drift 6b - Porphyritic biotite-quartz monzonite cover is thick and rock exposures are few and scattered while in the area 6c - Augite quartz monzonite between the Black River and Theresa and Dotted Lakes high bare ridges of 6d - Biotitic augite quartz monzonite metavolcanic rocks are separated oy large areas of low swampy ground. In 6e - Hybrid diorite this latter region the granitic areas in particular are poorly exposed and 6f - Hornblende-feldspar porphyry (dikes) swampy. 6g - Augite syenite(dikes) 6h - Hematitized, albitized quartz monzonite The eastern half of the area is accessible via Highway 17 and White Lake, Highway No. 614, Dead Otter Lake road, Ontario Paper Co. Intrusive Contact truck road and the Black River. The western half and northeastern corner GRANITIC GNEISSES are accessible via a number of lakes suitable for float plane landings. The nearest airbase is at White River which is approximately 40 miles east- 5a - Hornblende-biotite granite gneiss southeast of the area. ! 5b - Biotite granite gneiss 5c - Feldspar augen gneiss Mineral Exploration: Since the discovery of the orebodies in the Manitou• 5d - Migmatite wadge area in 1953 the whole district generally has been regarded with : 5e - Xenolithic granite gneiss interest. Claims have been staked and restaked at various times, mostly 5f - Hybrid granite gneiss along a belt extending northeast from Valley Lake to Dead Otter Lake. 5g - Hematitized, albitized granite gneiss Extensive new staking was done in the spring of 1965 in the area north, south, and west of Dotted and Dead Otter Lakes. In 1965 most of the ground Intrusive Contact between Dotted Lake, Theresa Lake and the Black River was covered by staking. MAFIC AND ULTRAMAFIC INTRUSIVE ROCKS In 1962 McIntyre Porcupine Mines Ltd. surveyed and drilled a 52 claim area enclosing the Von Klein (No.3) copper-nickel showing just east of Summers 4a - Amphibolitic metagabbro Lake on Highway No. 614. In 1963, some drilling was done by Mining Corpo• 4b - Serpentinite ration of Canada Ltd. in the area between Amwri Lake and the Black River 4c - Gabbro about ½ to 1 mile east of the river and in late 1963 T. and W, Kusins un• 4d - Talcose rock (dikes) covered a lead-zinc showing (No.2) between the Black River and Valley Lake, 4e - Anorthositic gneiss about ¾ mile west of the river. The Kusins showing was examined in 1965 by Cominco. In January 1966 Caravelle Mines Ltd. held a large block of Intrusive Contact more than 100 claims enclosing the Von Klein copper-nickel showing and extending from Theresa Lake in the east to Highway No. 614 on the west, south METASEDIMENTARY ROCKS of Dead Otter Lake. Also, Irish Copper Mines Ltd. held two blocks of claims 3a - Conglomerate and finely laminated north of Dotted Lake enclosing a zinc showing (No.4) staked by B. Fairservice.- greywacke Both companies flew geophysical surveys during the summer of 1965 and follow- 3b - Pyritic and (or) muscovite-quartz-feldspar up work is continuing. gneiss 3c - Biotite-quartz-feldspar paragneiss 3d - Feldspathized or migmatitic metasediments General Geology: The northern half and western parts of the area are under• or tuff lain essentially by granite gneisses and younger massive granitic rocks 3e - Garnet-biotite schist intruding these gneisses. The younger massive granitic rocks (6) have a 3f - Kyanite-garnet-quartz-feldspar gneiss relatively high magnetic response and the general outline of intrusions of 3g - Meta-arkose this material can be determined from aeromagnetic maps (Maps 2157G, 2158G, and 2168G). In the southeast quarter of the area east of the Black River, INTERMEDIATE TO SILICIC METAVOLCANICS, the rocks consist of a folded series of biotite-quartz-feldspar paragneisses, PYROCLASTIC ROCKS AND METASEDIMENTS conglomerates, hornblendic metatuffs and metavolcanic hornblende gneisses intruded by serpentinite, amphibolitic metagabbro, and massive granitic 2a - Porphyritic dacite (flows) rocks. The metasedimentary and metavolcanic rocks extend as a narrow 1 ½ 2b - Dacite flow breccia mile wide belt from south of Valley Lake, northeastwards to Highway No. 614 2c - Pillow lava where the belt swings east and widens to about 6 miles due to folding of 2d - Rhyolite breccia the metavolcanic rocks on the north side of the belt. These rocks strike 2e - Metarhyolite 2f - Intermediate to silicic welded tuff eastwards between Highway No. 614 and Theresa Lake and then swing southeast or flow breccia through White Lake to Highway No. 17. The flow rocks are predominantly 2g - Agglomerate, tuff, greywacke mafic hornblendic gneisses of formerly pillowed basaltic or andesitic 2h - Iron formation character. Porphyritic dacite pillow lavas occur west of the railroad track 2j - Biotite gneiss around Pinegrove Lake and dacitic flow breccia, rhyolite breccia, metarhyo-- 2k - Migmatite lite, tuff and agglomerate are exposed south of the amphibolitic metavolca• nic rocks, east and southwest of Summers Lake. Iron formation, which gives MAFIC TO INTERMEDIATE METAVOLCANIC ROCKS rise to a strong magnetic anomaly is exposed on the northwest side of the mafic metavolcanic ridge between Amwri Lake and the Black River and on the la - Medium-to fine-grained, massive and southeast side of this metavolcanic ridge, a band of pyritic muscovitic meta- gneissic amphibolite arkose extends from west of the Black River east to Phil Lake. The pyro- lb - Medium-to coarse-grained, massive and gneissic amphibolite clastic facies terminate just east of Theresa Lake and the mafic metavolcanic lc - Laminated hornblende gneiss rocks then lie in contact with conglomeratic metasediments to the south. 1d - Pillow lava The metasedimentary and metavolcanic rocks are intruded by granites, meta- le - Hematitized, epidotized metavolcanic rock gabbroic amphibolite sheets, serpentinite lenses and feldspar porphyry, 1f - Migmatite . amphibolitic, and dacite dikes. Large lenticular bodies of serpentinite are exposed at three locations; on the northeast shore of Dotted Lake, at the north end of Theresa Lake, and in Spruce Bay on the west side of White SYMBOLS FOR P. 332 - P. 335 Lake. All these bodies give rise to marked magnetic anomalies (Map 2168G). The youngest rocks in the area appear to be the diabases which form dikes Muskeg or swamp. Strike and dip of intruding all the previously mentioned formations. schistosity. River, creek, stream, Structure: The metasedimentary-metavolcanic belt of rocks represents the R = rapids; F = falls. southern limb of a roughly east-northeast trending anticlinorium. The south Strike of vertical side of the belt consists of metasediments and in this section the anticlinal schistosity. limb is slightly overturned to the south. The metavolcanic section on the Railway. north side of the belt is thickened by repetition caused by folding about Strike and dip of gneissosity. an east-northeast trending anticline centred on Dead Otter Lake and a para• llel syncline lying on the north side of Dotted Lake. These folds plunge Electric power transmission westwards, the plunge being about 20° near Roger Lake and steepening west• line. Strike of vertical wards to almost vertical at Highway No. 614. At the north contact of the gneissosity. metasedimentary-metavolcanic belt the foliation of the granite gneisses Highway. dips steeply south beneath the metavolcanic rocks but progressing north• wards the dips gradually shallow until, about 2 miles north of the contact Horizontal gneissosity. the dips are very shallow and in many places horizontal. The flat dip of Trail, portage, winter road. the foliation persists northwards to within 3 miles of Manitouwadge where Stratiform foliation, dip the foliation starts to dip predominantly north between 30° and 70°, unknown. beneath the metavolcanic rocks of the Manitouwadge syncline. Glacial striae. Economic Geology: The biotite-quartz-feldspar paragneisses of the Black Lineation (plunge known, River area are similar in appearance and composition to the metasedimentary Drift features. plunge unknown). gneisses of the Manitouwadge area. Unlike the Manitouwadge area, however, iron formation is relatively rare and was found in only two localities; one Small rock outcrop. between Amwri Lake and the Black River, close to the granite contact and Drag-folds. (Arrow indicates the other in the region of the Von Klein copper-nickel showing (No.3). direction of plunge). Both these occurrences contain pyrite and pyrrhotite. The most economically Boundary of rock outcrop. interesting feature in the area is a band of predominantly pyroclastic Wide shear zone. material, associated with some siliceous metasedimentary and intermediate to acid flow rocks, which extends from midway between Valley Lake and the Geological boundary, defined Black River, east-northeastwards for about 6 miles to Highway No. 614, Fault, indicated or assumed. just south of Summers Lake, then eastwards to north of Musher Lake and southeast to Theresa Lake. The rocks in this band are characteristically Geological boundary, garnetiferous hornblende metatuffs and agglomerates, siliceous biotite approximate. Lineament. gneisses, and muscovite gneisses frequently high in pyrite. The lead-zinc showing of T. and W. Kusins (No.2) is in metavolcanic hornblende gneiss Geological boundary, assumed. at the southwest end of this band. Silicified, pyritic, northeast-trending Location of mining property. zones occur in the hornblende gneiss and in one of these, small pods of sphalerite and galena occur with the pyrite. T. and W. Kusins report that Geological boundary as indi• Building. a grab sample gave on analysis 1.93 per cent zinc, 0.94 per cent lead and cated by geophysical data. O.64 oz. silver per ton. A major fault trending N65°W is believed to occur about 1,000 feet southwest of the showing. Gravel pit. Strike and dip; direction of top unknown. The Von Klein copper-nickel occurrences (No.3) are located Drill hole, inclination about halfway along the pyroclastic band about 1½ miles northwest of unknown. Musher Lake. The rocks in the vicinity of the showings are acid to inter• Strike and vertical dip; mediate flow rocks, breccias and pyroclastic rocks intruded by dacitic direction of top unknown. feldspar porphyry, biotite granite, muscovite granite and talcose ultra- Network of quartz veins. basic dikes There are several sulphide showings and, in what appear to be the two richest zones, chalcopyrite-pyrrhotite-pyrite mineralization seems Direction in which lava flows to be confined to two separate, large blocks of coarse-grained amphibolite; face as indicated by shape of Sulphide mineralization. one apparently is rafted in a rhyolite breccia (2d) plug and the other is pillows. in rhyolite or acid welded tuff (2fg). Mineralization in the surrounding Magnetic attraction. muscovite-biotite gneisses is minor. Some other showings with coppcr-nickel Synclinal axis. values occur in shear zones in the mafic pillow lavas (la) and garnetiferous agglomerates (2g) on the north side of the pyroclastic band. A geological Dikes. map of a 52-claim block was prepared by Mclntyre Porcupine Mines Ltd. in Anticlinal axis. 1962 and some drilling was done at that time. The drilling was concentrated mainly on the two main surface showings and this indicated little continuity Direction of plunge of fold Firetower. to the mineralized amphibolite blocks. A number of electromagnetic anoma• axis, crest line or trough lies unrelated to the two main showings were noted but these were examined line. only superficially. In 1965 Caravelle Mines Ltd. outlined several more electromagnetic anomalies and considered that these might relate to .he shear zone type of mineralization 0.1 the property. This investigation is MINERAL OCCURRENCES REFERENCE continuing. Cu Copper Pb Lead cp Chalcopyrite py Pyrite A small zinc showing (No.4) was located by B. Fairservice in mo Molybdenite po Pyrrhotite the mafic metavolcanic hornblende gneisses north of Dotted Lake and this Ni Nickel Zn Zinc prooerty was under examination by Irish Copper Mines Ltd. in 1965. The showing consists of 3 or 4 seams of massive sphalerite up to 1 inch in width in a short rusty shear zone up to 4 feet wide and about 50 feet long. No LIST OF PROPERTIES other mineralization was noted in the locality except for minor pyrite in 1. Mining Corporation of Canada Ltd. (1962). some quartz feldspar porphyry dikes which intrude the hornblende gneisses. 2. Kusins property (Cominco 1965). 3. Von Klein property (Mclntyre Porcupine Mines Ltd. 1962; Traces of mineralization were noted in three other localities. Carabclle Mines Ltd. 1065)- On Highway No. 614 and on the railroad track opposite the north end of East 4. Fairservice property (Trish Copper Mines Ltd. 1905). Barbara Lake a narrow band of massive and laminated metagabbro is inter- layered with the paragneiss. Disseminated pyrite is noticeable in the coarse-grained metagabbro on the railroad track and on Highway No. 614. SOURCES OF INFORMATION The laminated metagabbro outcrop on the east side of the road is cut by a thin 1-inch to 4-inch seam of black earthy weathered material containing Geology by V.G. Milne and assistants 1964, 1965. pvrite. A second small showing was located on the Ontario Paper Company Assessment file No. 63-1210, Ontario Dept. Mines. road opposite the north end of Morely Lake. The road cuts through a small Ontario Dept. Mines, Vol. XXXI, 1932, pt. 6 outcrop of amphibolite metagabbro in a generally drift-covered area. The Ontario Dept. Mines, Vol. LXVT, 1957, pt. 8. amphibolite contains a little disseminated pyrite and is cut by scattered Geological Report on the Hemlo area, Dept. of Industrial Development, thin rusty fractures containing occasional small blebs of pyrite. On the Canadian Pacific Railway, 1957. west side of the road a loose block blasted from the outcrop shows local shearing along a rusty fracture and associated with this a small 4 to Base map from maps of Forest Resources Inventory, Ontario Department of 6-inch diameter pod of massive pyrrhotite, chalcopyrite and pyrite. The Lands and Forests, with additional information by V.G. Milne. third locality is a small outcrop of game t if erous amphibolite 0.1 the Ontario Paper Company road east of the south end of Agoazoa Lake Widely scattered, thin, rusty pyrite-coated fractures cut the rock and locally a Issued 1966. thin veneer of molybdenite coats the fractures. ONTARIO DEPARTMENT OF MINES PRELIMINARY GEOLOGICAL MAP No. P. 331 BLACK RIVER AREA NORTHEAST PART DISTRICT OF THUNDER BAY Scale 1 inch to ½ mile N.T.S. Reference: 42C/13, 42F/4 G.S.C.-O.D.M. Aeromagnetic Maps: 216SG, 2169G. LEGEND FOR P. 332 - P. 335 PHANEROZOIC CEN0ZOIC PLEISTOCENE AND RECENT Varved clay, silty sand, sand and gravel Unconformity MARGINAL NOTES PRECAMBRIAN PROTEROZOIC Introduction: The area lies between latitudes 48º45' and 49°07' and longi• KEWEENAWAN tudes 85°32' and 86°05' in the District of Thunder Bay. The eastern limit of the area follows the west boundaries of Bryant, Atikameg and McGill 8a - Diabase (dikes) townships and the west limit is marked by the east boundary of Township 75 8b - Porphyritic diabase (dikes) and corresponds to the east boundaries of preliminary maps Nos. P. 233 and P. 235- Highway No. 614 to Manitouwadge runs north-south through the centre Intrusive Contact of the area and the southern limit of the map is about 4 miles north of the junction between this highway and Trans Canada Highway No. 17. The northern ARCHEAN limit of the area corresponds to the southern limit of the Manitouwadge Area Map No. 1957-8. POST-TECTONIC GRANITIC ROCKS 7a - Biotite granite The Black River meanders roughly south-southwest through the 7b - Biotite granite (dikes) centre of the area and lies in a relatively wide low valley floored by 7c - Feldspar porphyry (dikes) thick deposits of glaciolacustrine varved clays and silty sands with coarse 7d - Leucocratic biotite granite (dikes) sands and minor gravels. The rocks underlying the area west of the Black 7e - Aplite and pegmatite (dikes) River and north of Mobert Creek are predominantly granitic. These granites 7f - Muscovite granite (dikes) are well exposed and high bare ridges are common. The trend of these 7g - Lamprophyre ridges is controlled by the gneissosity and jointing and northeast-southwest 7h - Hematitized, albitized granite trending valleys have been accentuated by glacial scouring. In the Black Rive 7k - Xenolithic granite valley, Nama Creek valley, Wabikoba Lake and south White Lake areas drift 6a - Hornblende-biotite quartz monzonite cover is thick and rock exposures are few and scattered while in the area 6b - Porphyritic biotite-quartz monzonite between the Black River and Theresa and Dotted Lakes high bare ridges of 6c - Augite quartz monzonite metavolcanic rocks are separated by large areas of low swampy round. In 6d - Biotitic augite quartz monzonite this latter region the granitic areas in particular are poorly exposed and 6e - Hybrid diorite swampy. 6f - Hornblende-feldspar porphyry (dikes) 6g - Augite syenite (dikes) The eastern half of the area is accessible via Highway 17 6h - Hematitized, albitized quartz monzonite and White Lake, Highway No. 614, Dead Otter Lake road, Ontario Paper Co. truck road and the Black River. The western half and northeastern corner Intrusive Contact are accessible via a number of lakes suitable for float plane landings. GRANITIC GNEISSES The nearest airbase is at White River which is approximately 40 miles east- southeast of the area. 5a - Hornblende-biotite granite gneiss 5b - Biotite granite gneiss Mineral Exploration: Since the discovery of the orebodies in the Manitou• 5c - Feldspar augen gneiss wadge area in 1953 the whole district generally has been regarded with 5d - Migmatite interest. Claims have been staked and restaked at various times, mostly 5e - Xenolithic granite gneiss along a belt extending northeast from Valley Lake to Dead Otter Lake. 5f - Hybrid granite gneiss Extensive new staking was done in the spring of 1965 in the area north, 5g - Hematitized, albitized granite gneiss south, and west of Dotted and Dead Otter Lakes. In 1965 most of the ground between Dotted Lake, Theresa Lake and the Black River was covered by staking. Intrusive Contact In 1962 McIntryre Porcupine Mines Ltd. surveyed and drilled a 52 claim area MAFIC AND ULTRAMAFIC INTRUSIVE ROCKS enclosing the Von Klein (No.3) copper-nickel showing just east of Summers Lake on Highway No. 614. In 1963, some drilling was done by Mining Corpo- 4a - Amphibolitic metagabbro ration of Canada Ltd. in the area between Amwri Lake and the Black River 4b - Serpentinite about ½ to 1 mile east of the river and in late 1963 T. and W. Kusins un• 4c - Gabbro covered a lead-zinc showing (No.2) between the Black River and Valley Lake, 4d - Talcose rock (dikes) about ¾ mile west of the river. The Kusins showing was examined in 1965 4e - Anorthositic gneiss by Cominco. In January 1966 Caravelle Mines Ltd. held a large block of more than 100 claims enclosing the Von Klein copper-nickel showing and Intrusive Contact extending from Theresa Lake in the east to Highway No. 614 on the west, south of Dead Otter Lake. Also, Irish Copper Mines Ltd. held two blocks of claims METASEDIMENTARY ROCKS north of Dotted Lake enclosing a zinc showing (No.4) staked by B. Fairservice. Both companies flew geophysical surveys during the summer of 1965 and follow- 3a - Conglomerate and finely laminated greywacke up work is continuing. 3b - Pyritic and (or) muscovite-quartz-feldspar gneiss General Geology: The northern half and western parts of the area are under• 3c - Biotite-quartz-feldspar paragneiss lain essentially by granite gneisses and younger massive granitic rocks 3d - Feldspathized or migmatitic metasediments or tuff intruding these gneisses. The younger massive granitic rocks (6) have a 3e - Garnet-biotite schist relatively high magnetic response and the general outline of intrusions of 3f - Kyanite-garnet-quartz-feldspar gneiss thjs material can be determined from aeromagnetic maps (Maps 2157G, 2158G, 3g - Meta-arkose and 2168G). In the southeast quarter of the area east of the Black River, the rocks consist of a folded series of biotite-quartz-feldspar paragneisses, INTERMEDIATE TO SILICIC METAVOLCANICS, conglomerates, hornblendic metatuffs and metavolcanic hornblende gneisses PYROCLASTIC ROCKS AND METASEDIMENTS intruded by serpentinite, amphibolitic metagabbro, and massive granitic rocks. The metasedimentary and metavolcanic rocks extend as a narrow 1 2 2a - Porphyritic dacite (flows) mile wide belt from south of Valley Lake, northeastwards to Highway No. 614 2b - Dacite flow breccia where the belt swings east and widens to about 6 miles due to folding of 2c - Pillow lava the metavolcanic rocks on the north side of the belt. These rocks strike 2d - Rhyolite breccia eastwards between Highway No. 614 and Theresa Lake and then swing southeast 2e - Metarhyolite through White Lake to Highway No. 17. The flow rocks are predominantly 2f - Intermediate to silicic welded tuff or flow breccia mafic hornblendic gneisses of formerly pillowed basaltic or andesitic 2g - Agglomerate, tuff, greywacke character. Porphyritic dacite pillow lavas occur west of the railroad track 2h - Iron formation around Pinegrove lake and dacitic flow breccia, rhyolite breccia, metarhyo-- 2j - Biotite gneiss -lite, tuff and agglomerate are exposed south of the amphibolitic metavolca• 2k - Migmatite nic rocks, east and southwest of Summers Lake. Iron formation, which gives rise to a strong magnetic anomaly is exposed 0:1 the northwest side of the MAFIC TO INTERMEDIATE METAVOLCANIC ROCKS mafic metavolcanic ridge between Amwri Lake and the Black River and on the southeast side of this metavolcanic ridge, a band of pyritic muscovitic meta- la - Medium-to fine-grained, massive and arkose extends from west of the Black River east to Phil Lake. The pyro- gneissic amphibolite clastic fades terminate just east of Theresa Lake and the mafic metavolcanic lb - Medium-to coarse-grained, massive and rocks then lie in contact with conglomeratic metasediments to the south. gneissic amphibolite lc - Laminated hornblende gneiss The metasedimentary and metavolcanic rocks are intruded by granites, meta- 1d - Pillow lava gabbroic amphibolite sheets, serpentinite lenses and feldspar porphyry, le - Hematitized, epidotized metavolcanic rock amphibolitic, and dacite dikes. Large lenticular bodies of serpentinite 1f - Migmatite are exposed at three locations; on the northeast shore of Dotted Lake, at the north end of Theresa Lake, and in Spruce Bay on the west side of White Lake. All these bodies give rise to marked magnetic anomalies (Map 2168G). SYMBOLS FOR P. 3,32 - P. 335 The youngest rocks in_the area appear to be the diabases which form dikes intruding all the previously mentioned formations. Muskeg or swamp. Strike and dip of Schistosity. Structure: The metasedimentary-metavolcanic belt of rocks represents the River, creek, stream, southern limb of a roughly east-northeast trending anticlinorium. The south R = rapids; F = falls. Strike of vertical side of the belt consists of metasediments and in this section the anticlinal schistosity. limb is slightly overturned to the south. The metavolcanic section on the north side of the belt is thickened by repetition caused by folding about Railway. an east-northeast trending anticline centred on Dead Otter Lake and a para• Strike and dip of gneissosity. llel syncline lying on the north side of Dotted Lake. These folds plunge westwards, the plunge being about 20° near Roger lake and steepening west• Electric power transmission wards to almost vertical at Highway No. 614. At the north contact of the line. Strike of vertical metasedimentary-metavolcanic belt the foliation of the granite gneisses gneissosity. dips steeply south beneath the metavolcanic rocks but progressing north• Highway. wards the dips gradually shallow until, about 2 miles north of the contact Horizontal gneissosity. the dips are very shallow and in many places horizontal. The flat dip of the foliation persists northwards to within 3 miles of Manitouwadge where Trail, portage, winter road. the foliation starts to dip predominantly north between 30° and 70°, Stratiform foliation, dip beneath the metavolcanic rocks of the Manitouwadge synclinc. unknown. Glacial striae- Economic Geology: The biotite-quartz-feldspar paragneisses of the Black Lineation (plunge Known, River area arc similar in appearance and composition to the metasedimentary Drift features. gneisses of the Manitouwadge area. Unlike the Manitouwadge area, however, plunge unknown). iron formation is relatively rare and was found in only two localities; one between Amwri Lake and the Black River, close to the granite contact and Small rock outcrop. Drag-folds. (Arrow indicates the other in the region of the Von Klein copper-nickel showing (No.3). direction of plunge). Both these occurrences contain pyrite and pyrrhotite. The most economically interesting feature in the area is a band of predominantly pyroclastic Boundary of rock outcrop. material, associated with some siliceous metasedimentary and intermediate Wide shear zone. to acid flow rocks, which extends from midway between Valley Lake and the Geological boundary, defined Black River, east-northeastwards for about 6 miles to Highway No. 614, just south of Summers Lake, then eastwards to north of Musher Lake and Fault, indicated or assumed. southeast to Theresa lake. The rocks in this band are characteristically Geological boundary, garnetiferous, hornblende metatuffs and agglomerates, siliceous biotite approximate. Lineament. gneisses, and muscovite gneisses frequently high in pyrite. The lead-zinc showing of T. and W. Kusins (No.2) is in metavolcanic hornblende gneiss at the southwest end of this band. Silicified, pyritic, northeast-trending Geological boundary, assumed. Location of mining property. zones occur in the hornblende gneiss and in one of these, small pods of sphalerite and galena occur with the pyrite. T. and W. Kusins report that Geological boundary as indi• Building. a grab sample gave on analysis 1.93 per cent zinc, 0.94 per cent lead and cated by geophysical data. 0.64 oz. silver per ton. A major fault trending N65°W is believed to occur about 1,000 feet southwest of the showing. Gravel pit. Strike and dip; direction The Von Klein copper-nickel occurrences (No.3) are located of top unknown. about halfway along the pyroclastic band about 1½ miles northwest of Drill hole, inclination Musher Lake. The rocks in the vicinity of the showings are acid to inter• unknown. mediate flow rocks, breccias and pyroclastic rocks intruded by dacitic Strike and vertical dip; feldspar porphyry, biotite granite, muscovite granite and talcose ultra- direction of top unknown. basic dikes. There are several sulphide showings and, in what appear to be Network of quartz veins. the two richest zones, chalcopyrite-pyrrhotite-pyrite mineralization seems Direction in which lava flows to be confined to two separate, large blocks of coarse-grained amphibolite; face as indicated by shape of Sulphide mineralization. one apparently is rafted in a rhyolite breccia (2d) plug and the other is pillows. in rhyolite or acid welded tuff (2fg). Mineralization in the surrounding muscovite-biotite gneisses is minor. Some other showings with copper-nickel Magnetic attraction. values occur in shear zones in the mafic pillow lavas (1a) and garnetiferous Synclinal axis. Agglomerates (2g) on the north side of the pyroclastic band. A geological map of a 52-claim block was prepared by McIntyre Porcupine Mines Ltd. in Dikes. 1962 and some drilling was done at that time. The drilling was concentrated Anticlinal axis. mainly on the two main surface showings and this indicated little continuity to the mineralized amphibolite blocks. A number of electromagnetic anoma• Direction of plunge of fold Firetower. lies unrelated to the two main showings were noted but these were examined axis, crest line or trough only superficially. In 1965 Caravelle Mines Ltd. outlined several more line. electromagnetic anomalies and considered that these might relate to the shear zone type of mineralization on the property. This investigation is MINERAL OCCURRENCES REFERENCE continuing. Cu Copper Pb Lead A small zinc showing (No.4) was located by B. Fairservice in cp Chalcopyrite py Pyrite the mafic metavolcanic hornblende gneisses north of Dotted Lake and this mo Molybdenite po Pyrrhotite property was under examination by Irish Copper Mines Ltd. in 1965. The Ni Nickel Zn Zinc showing consists of 3 or 4 seams of massive sphalerite up to 1 inch in width in a short rusty shear zone up to 4 feet wide and about 50 feet long. No LIST OF PROPERTIES other mineralization was noted in the locality except for minor pyrite m some quartz feld3par porphyry dikes which intrude the hornblende gneisses. 1. Mining Corporation of Canada Ltd. (1962). 2. Kusins property (Cominco 1965). Traces of mineralization were noted in three other localities. 3. Von Klein property (Mclntyre Porcupine Mines Ltd. 1962; On Highway No. 614 and on the railroad track opposite the north end of East Carabelle Mines Ltd. 1965). Barbara Lake a narrow band of massive and laminated metagabbro is inter- 4. Fairservice property (Irish Copper Mines Ltd. I965). layered with the paragneiss. Disseminated pyrite is noticeable in the coarse-gained metagabbro on the railroad track and on Highway No. 614. The laminated metagabbro outcrop on the east side of the road is cut by a SOURCES OF INFORMATION thin 1-inch to 4-inch seam of black earthy weathered material containing Geology by V.G. Milne and assistants 1964, 1965. pyrite. A second small showing was located on the Ontario Paper Company Assessment file No. 63-1210, Ontario Dept. Mines. road opposite the north end of Morely Lake. The road cuts through a small Ontario Dept. Mines, Vol. XXXI, 1932, pt. 6 outcrop of amphibolite metagabbro in a generally drift-covered area. The Ontario Dept. Mines, Vol. LXVI, 1957, pt. 8. amphibolite contains a little disseminated pyrite and is cut by scattered Geological Report on the Hemlo area, Dept. of Industrial Development, thin, rusty fractures containing occasional small blebs of pyrite. On the Canadian Pacific Railway, 1957. west side of the road a loose block blasted from the outcrop shows local shearing along a rusty fracture and associated with this a small 4 to Base map from maps of Forest Resources Inventory, Ontario Department of 6-inch diameter pod of massive pyrrhotite, chalcopyrite and pyrite. the Lands and Forests, with additional information by V.G. Milne. third locality is a small outcrop of garnetiferous amphibolite on the Ontario Paper Company road east of the south end of Agoazoa Lake. Widely scattered, thin, rusty pyrite-coated fractures cut the rock and locally a Issued 1966. thin veneer of molybdenite coats the fractures. ONTARIO DEPARTMENT OF MINES PRELIMINARY GEOLOGICAL MAP No. P. 334 BLACK RIVER AREA SOUTHWEST PART DISTRICT OF THUNDER BAY Scale 1 inch to ½ mile N.T.S. Reference: 42D/16, 42C/13 G.S.C.-O.D.M. Aeromagnetic Maps: 2157G, 2168G. LEGEND FOR P. 3.32 - P. 335 PHANEROZOIC CENOZOIC PLEISTOCENE AND RECENT Varved clay, silty sand, sand and gravel Unconformity PR ECAMBRIAN MARGINAL NOTES PROTEROZOIC KEWEENAWAN Introduction: The area lies between latitudes 48°45' and 49°07' and longi• tudes 85°32' and 86°05' in the District of Thunder Bay. The eastern limit 8a - Diabase (dikes) of the area follows the west boundaries of Bryant, Atikameg and McGill 8b - Porphyritic diabase (dikes) townships and the west limit is marked by the east boundary of Township 75 and corresponds to the east boundaries of preliminary maps Nos. P. 233 and Intrusive Contact P.235- Highway No. 614 to Manitouwadge runs north-south through the centre of the area and the southern limit of the map is about 4 miles north of the ARCHEAN junction between this highway and Trans Canada Highway No. 17. The northern limit of the area corresponds to the southern limit of the Manitouwadge Area POST-TECTONIC GRANITIC ROCKS Map No. 1957-8. 7a - Biotite granite 7b - Biotite granite (dikes) The Black River meanders roughly south-southwest through the 7c - Feldspar porphyry (dikes) centre of the area and lies in a relatively wide low valley floored by 7d - Leucocratic biotite granite (dikes) thick deposits of glaciolacustrine varved clays and silty sands with coarse 7e - Aplite and pegmatite (dikes) sands and minor gravels. The rocks underlying the area west of the Black 7f - Muscovite granite (dikes) River and north of Mobert Creek are predominantly granitic. These granites 7g - Lamprophyre are well exposed and high bare ridges are common. The trend of these 7h - Hematitized, albitized granite ridges is controlled by the gneissosity and jointing and northeast-southwest 7k - Xenolithic granite trending valleys have been accentuated by glacial scouring. In the Black River 6a - Hornblende-biotite quartz monzonite valley, Nama Creek valley, Wabikoba Lake and south White Lake areas drift 6b - Porphyritic biotite-quartz monzonite cover is thick and rock exposures are few and scattered while in the area 6c - Augite quartz monzonite between the Black River and Theresa and Dotted Lakes high bare ridges of 6d - Biotitic augite quartz monzonite metavolcanic rocks are separated by large areas of low swampy ground. In 6e - Hybrid diorite this latter region the granitic areas in particular are poorly exposed and 6f - Hornblende-feldspar porphyry (dikes) swampy. 6g - Augite syenite (dikes) 6h - Hematitized, albitized quartz monzonite The eastern half of the area is accessible via Highway 17 and White Lake, Highway No. 614, Dead Otter Lake road, Ontario Paper Co. Intrusive Contact truck road and the Black River. The western half and northeastern corner GRANITIC GNEISSES are accessible via a number of lakes suitable for float plane landings. The nearest airbase is at White River which is approximately 4° miles east- 5a - Hornblende-biotite granite gneiss southeast of the area. 5b - Biotite granite gneiss 5c - Feldspar augen gneiss Mineral Exploration: Since the discovery of the orebodies in the Manitou• 5d - Migmatite wadge area in 1953 the whole district generally has been regarded with 5e - Xenolithic granite gneiss interest. Claims have been staked and restaked at various times, mostly 5f - Hybrid granite gneiss along a belt extending northeast from Valley Lake to Dead Otter Lake. 5g - Hematitized, albitized granite gneiss Extensive new staking was done in the spring of 1965 in the area north, south, and west of Dotted and Dead Otter Lakes. In 1965 most of the ground Intrusive Contact between Dotted Lake, Theresa Lake and the Black River was covered by staking. MAFIC AND ULTRAMAFIC INTRUSIVE ROCKS In 1962 McIntyre Porcupine Mines Ltd. surveyed and drilled a 52 claim area enclosing the Von Klein (No.3) copper-nickel showing just east of Summers 4a - Amphibolitic metagabbro Lake on Highway No. 614. In 1963, some drilling was done by Mining Corpo• 4b - Serpentinite ration of Canada Ltd. in the area between Amwri Lake and the Black River 4c - Gabbro about ½ to 1 mile east of the river and in late 1963 T. and W. Kusins un• 4d - Talcose rock (dikes) covered a lead-zinc showing (No.2) between the Black River and Valley Lake, 4e - Anorthositic gneiss about ¾ mile west of the river. The Kusins showing was examined in 1965 by Cominco. In January 1966 Caravelle Mines Ltd. held a large block of Intrusive Contact more than 100 claims enclosing the Von Klein copper-nickel showing and extending from Theresa Lake in the east to Highway No. 614 on the west, south METASEDIMENTARY ROCKS of Dead Otter Lake. Also, Irish Copper Mines Ltd. held two blocks of claims 3a - Conglomerate and finely laminated north of Dotted Lake enclosing a zinc showing (No.4) staked by B. Fairservice. greywacke Both companies flew geophysical surveys during the summer of I965 and follow- 3b - Pyritic and (or) muscovite-quartz-feldspar up work is continuing. gneiss 3c - Biotite-quartz-feldspar paragneiss 3d - Feldspathized or migmatitic metasediments General Geology: The northern half and western parts of the area are under• or tuff lain essentially by granite gneisses and younger massive granitic rocks 3e - Garnet-biotite schist intruding these gneisses. The younger massive granitic rocks (6) have a 3f - Kyanite-garnet-quartz-feldspar gneiss relatively high magnetic response and the general outline of intrusions of 3g - Meta-arkose this material can be determined from aeromagnetic maps (Maps 2157G, 215SG, and 2168G). In the southeast quarter of the area east of the Black River, INTERMEDIATE TO SILICIC METAVOLCANICS, the rocks consist of a folded series of biotite-quartz-feldspar paragneisses, PYROCLASTIC ROCKS AND METASEDIMENTS conglomerates, hornblendic metatuffs and metavolcanic hornblende gneisses intruded by serpentinite, amphibolitic metagabbro, and massive granitic 2a - Porphyritic dacite (flows) rocks. The metasedimentary and metavolcanic rocks extend as a narrow 1 ½ 2b - Dacite flow breccia mile wide belt from south of Valley Lake, northeastwards to Highway No. 614 2c - Pillow lava where the belt swings east and widens to about 6 miles due to folding of 2d - Rhyolite breccia the metavolcanic rocks on the north side of the belt. These rocks strike 2e - Metarhyolite 2f - Intermediate to silicic welded tuff eastwards between Highway No. 614 and Theresa Lake and then swing southeast or flow breccia through White Lake to Highway No. 17. The flow rocks are predominantly 2g - Agglomerate, tuff, greywacke mafic hornblendic gneisses of formerly pillowed basaltic or andesitic 2h - Iron formation character. Porphyritic dacite pillow lavas occur west of the railroad track 2j - Biotite gneiss around Pinegrove Lake and dacitic flow breccia, rhyolite breccia, metarhyo-- 2k - Migmatite lite, tuff and agglomerate are exposed south of the amphibolitic metavolca• nic rocks, east and southwest of Summers Lake. Iron formation, which gives MAFIC TO INTERMEDIATE METAVOLCANIC ROCKS rise to a strong magnetic anomaly is exposed on the northwest side of the mafic metavolcanic ridge between Amwri Lake and the Black River and on the la - Medium-to fine-grained, massive and southeast side of this metavolcanic ridge, a band of pyritic muscovitic meta- gneissic amphibolite arkose extends from west of the Black River east to Phil Lake. The pyro• lb - Medium-to coarse-grained, massive and gneissic amphibolite clastic facies terminate just east of Theresa Lake and the mafic metavolcanic 1c - Laminated hornblende gneiss rocks then lie in contact with conglomeratic metasediments to the south. 1d - Pillow lava The metasedimentary and metavolcanic rocks are intruded by granites, meta- 1e - Hematitized, epidotized metavolcanic rock gabbroic amphibolite sheets, serpentinite lenses and feldspar porphyry, 1f - Migmatite amphibolitic, and dacite dikes. Large lenticular bodies of serpentinite are exposed at three locations; on the northeast shore of Dotted Lake, at the north end of Theresa Lake, and in Spruce Bay on the west side of White SYMBOLS FOR P. 332 - P. 335 Lake. All these bodies give rise to marked magnetic anomalies (Map 2168G). The youngest rocks in the area appear to be the diabases which form dikes Muskeg or swamp. Strike and dip of intruding all the previously mentioned formations. schistosity. Structure: The metasedimentary-metavolcanic belt of rocks represents the River, creek, stream, southern limb of a roughly east-northeast trending anticlinorium. The south R = rapids; F = falls. Strike of vertical side of the belt consists of metasediments and in this section the anticlinal schistosity. limb is slightly overturned to the south. The metavolcanic section on the Railway. north side of the belt is thickened by repetition caused by folding about Strike and dip of gneissosity. an east-northeast trending anticline centred on Dead Otter Lake and a para• llel syncline lying on the north side of Dotted Lake. These folds plunge Electric power transmission westwards, the plunge being about 20° near Roger Lake and steepening west• 1 ine. Strike of vertical wards to almost vertical at Highway No. 614. At the north contact of the gneissosity. metasedimentary-metavolcanic belt the foliation of the granite gneisses dips steeply south beneath the metavolcanic rocks but progressing north• Highway. wards the dips gradually shallow until, about 2 miles north of the contact Horizontal gneissosity. the dips are very shallow and in many places horizontal. The flat dip of Trail, portage, winter road. the foliation persists northwards to within 3 miles of Manitouwadge where the foliation starts to dip predominantly north between 30° and 70°, Stratiform foliation, dip unknown. beneath the metavolcanic rocks of the Manitouwadge syncline. Glacial striae. Economic Geology: The biotite-quartz-feldspar paragneisses of the Black Lineation (plunge known, River area are similar in appearance and composition to the metasedimentary Drift features. plunge unknown). gneisses of the Manitouwadge area. Unlike the Manitouwadge area, however, iron formation is relatively rare and was found in only two localities; one Small rock outcrop. between Amwri Lake and the Black River, close to the granite contact and Drag-folds. (Arrow indicates the other in the region of the Von Klein copper-nickel showing (No. 3). direction of plunge). Both these occurrences contain pyrite and pyrrhotite. The most economically Boundary of rock outcrop. interesting feature in the area is a band of predominantly pyroclastic Wide shear zone. material, associated with some siliceous metasedimentary and intermediate to acid flow rocks, which extends from midway between Valley Lake and the Geological boundary, defined Black River, east-northeastwards for about 6 miles to Highway No. 614, Fault, indicated or assumed. just south of Summers Lake, then eastwards to north of Musher Lake and southeast to Theresa Lake. The rocks in this band are characteristically Geological boundary, garnetiferous hornblende metatuffs and agglomerates, siliceous biotite approximate. Lineament. gneisses, and muscovite gneisses frequently high in pyrite. The lead-zinc showing of T. and W. Kusins (No.2) is in metavolcanic hornblende gneiss Geological boundary, assumed. at the southwest end of this band. Silicified, pyritic, northeast-trending Location of mining property. zones occur in the hornblende gneiss and in one of these, small pods of sphalerite and galena occur with the pyrite. T. and W. Kusins report that Geological boundary as indi• Building. a grab sample gave on analysis 1.93 per cent zinc, 0.94 per cent lead and cated by geophysical data. 0.64 oz. silver per ton. A major fault trending N65°W is believed to occur about 1,000 feet southwest of the showing. Gravel pit. Strike and dip; direction of top unknown. The Von Klein copper-nickel occurrences .(No.3) arc located Drill hole, inclination about halfway along the pyroclastic band about 1½ miles northwest of unknown. Musher Lake. The rocks in the vicinity of the showings are acid to inter• Strike and vertical dip; mediate flow rocks, breccias and pyroclastic rocks intruded by dacitic direction of top unknown. feldspar porphyry, biotite granite, muscovite granite and talcose ultra- Network of quartz veins. basic dikes. There are several sulphide showings and, in what appear to be the two richest zones, chalcopyrite-pyrrhotite-pyrite mineralization seems Direction in which lava flows to be confined to two separate, large blocks of coarse-grained amphibolite; face as indicated by shape of Sulphide mineralization. one apparently is rafted in a rhyolite breccia (2d) plug and the other is pillows. in rhyolite or acid welded tuff (2fg). Mineralization in the surrounding muscovite-biotite gneisses is minor. Some other showings with copper-nickel Magnetic attraction. values occur in shear zones in the mafic pillow lavas (la) and garnetiferous Synclinal axis. agglomerates (2g) on the north side of the pyrociastic band. A geological Dikes. map of a 52-claim block was prepared by Mclntyre Porcupine Mines Ltd. in Anticlinal axis. 1962 and some drilling was done at that time. The drilling was concentrated mainly on the two main surface showings and this indicated little continuity Direction of plunge of fold Firetower. to the mineralized amphibolite blocks. A number of electromagnetic anoma• axis, crest line or trough lies unrelated to the two main showings were noted but these were examined line. only superficially. In 1965 Caravelle Mines Ltd. outlined several move electromagnetic anomalies and considered that these might relate to the shear zone type of mineralization on the property. This investigation is MINERAL OCCURRENCES REFERENCE continuing. Cu Copper Pb Lead cp Chalcopyrite py Pyrite A small zinc showing (No.4) was located by B. Fairservice in mo Molybdenite po Pyrrhotite the mafic metavolcanic hornblende gneisses north of Dotted Lake and this Ni Nickel Zn Zinc property was under examination by Irish Copper Mines Ltd. in 1965. The showing consists of 3 or 4 seams of massive sphalerite up to 1 inch in width in a short rusty shear zone up to 4 feet wide and about 50 feet long. No LIST OF PROPERTIES other mineralization was noted in the locality except for minor pyrite in 1. Mining Corporation of Canada Ltd. (1962). some quartz feldspar porphyry dikes which intrude the hornblende gneisses. 2. Kusins property (Cominco 1965). 3. Von Klein property (Mclntyre Porcupine Mines Ltd. 1962; Traces of mineralization were noted in three other localities. Carabelle Mines Ltd. 1965). On Highway No. 614 and on the railroad track opposite the north end of East 4. Fairservice property (Irish Copper Mines Ltd. 1965). Barbara Lake a narrow band of massive and laminated metagabbro is inter- layered with the paragneiss. Disseminated pyrite is noticeable in the coarse-grained metagabbro on the railroad track and on Highway No. 614. SOURCES OF INFORMATION The laminated metagabbro outcrop on the east side of the road is cut by a thin 1-inch to 4-inch seam of black earthy weathered material containing Geology by V.G. Milne and assistants 1964, 1965. pyrite. A second small showing was located on the Ontario Paper Company Assessment file No. 63-1210, Ontario Dept. Mines. road opposite the north end of Morely Lake. The road cuts through a small Ontario Dept. Mines, Vol. XXXI, 1932, pt. 6 outcrop of amphibolite metagabbro in a generally drift-covered area. The Ontario Dept. Mines, Vol. LXVI, 1957, pt. 8. amphibolite contains a little disseminated pyrite and is cut by scattered Geological Report on the Hemlo area, Dept. of Industrial Development, thin rusty fractures containing occasional small blebs of pyrite. On the Canadian Pacific Railway, 1957. west side of the road a loose block blasted from the outcrop shows local shearing along a rusty fracture and associated with this a small 4 to Base map from maps of Forest Resources Inventory, Ontario Department of 6-inch diameter pod of massive pyrrhotite, chalcopyritc and pyrite. The Lands and Forests, with additional information by V.G. Milne. third locality is a small outcrop of garnetiferous amphibolite on the Ontario Paper Company road east of the south end of Agoazoa Lake. Widely scattered, thin, rusty pyrite-coated fractures cut the rock and locally a Issued 1966. thin veneer of molybdenite coats the fractures. ONTARIO DEPARTMENT OF MINES PRELIMINARY GEOLOGICAL MAP No. P. 335 BLACK RIVER AREA SOUTHEAST PART DISTRICT OF THUNDER BAY Scale 1 inch to ½ mile N.T.S. Reference: 42C/13 G.S.C.-O.D.M. Aeromagnetic Map: 2168G. LEGEND FOR P. 33 2 - P. 335 FHAN EROZOIC CENOZOIC PLEISTOCENE AND RECENT Varved clay, silty sand, sand and gravel Unconformity MARGINAL NOTES PRECAMBRIAN PR0TEROZOIC Introduction The area lies between latitudes 48°45' and 49°07' and longi- KEWEENAWAN tudes 85°32' and 86°05', in the District of Thunder Bay. The eastern limit of the area follows the west boundaries of Bryant, Atikameg and McGill 8a - Diabase (dikes) townships and the west limit is marked by the east boundary of Township 75 8b - Porphyritic diabase (dikes) and corresponds to the east boundaries of preliminary maps Nos. P. 233 and Intrusive Contact P.235. Highway No. 614 to Manitouwadge runs north-south through the centre of the area and the southern limit of the map is about 4 miles north of the ARCHEAN junction between this highway and Trans Canada Highway No. 17. The northern limit of the area corresponds to the southern limit of the Manitouwadge Area POST-TECTONIC GRANITIC ROCKS Map No. 1957-8. 7a - Biotite granite 7b - Biotite granite (dikes) The Black River meanders roughly south-southwest through the 7c - Feldspar porphyry (dikes) centre of the area and lies in a relatively wide low valley floored by 7d - Leucocratic biotite granite (dikes) thick deposits of glaciolacustrine varved clays and silty sands with coarse 7e - Aplite and pegmatite (dikes) sands and minor gravels. The rocks underlying the area west of the Black 7f - Muscovite granite (dikes) River and north of Mobert Creek are predominantly granitic. These granites 7g - Lamprophyre are well exposed and high bare ridges are common. The trend of these 7h - Hematitized, albitized granite ridges is controlled by the gneissosity and jointing and northeast-southwest 7k - Xenolithic granite trending valleys have been accentuated by glacial scouring. In the Black River valley, Nama Creek valley, Wabikoba Lake and south White Lake areas drift 6a - Hornblende-biotite quartz monzonite 6b - Porphyritic biqtite-quartz monzonite cover is thick and rock exposures are few and scattered while in the area 6c - Augite quartz monzonite between the Black River and Theresa and Dotted Lakes high bare ridges of 6d - Biotitic augite quartz monzonite metavolcanic rocks are separated by large areas of low swampy ground. In 6e - Hybrid diorite this latter region the granitic areas in particular are poorly exposed and 6f - Hornblende-feldspar porphyry (dikes) swampy. 6g - Augite syenite (dikes) The eastern half of the area is accessible via Highway 17 6h - Hematitized, albitized quartz monzonite and White Lake, Highway No. 614, Dead Otter Lake road, Ontario Paper Co. Intrusive Contact truck road and the Black River. The western half and northeastern corner are accessible via a number of lakes suitable for float plane landings. GRANITIC GNEISSES The nearest airbase is at White River which is approximately 40 miles east- 5a - Hornblende-biotite granite gneiss southeast of the area. 5b - Diotite granite gneiss 5c - Feldspar augen gneiss Mineral Exploration: Since the discovery of the orebodies in the Manitou• 5d - Migmatite wadge area in 1953 the whole district generally has been regarded with 5e - Xenolithic granite gneiss interest. Claims have been staked and restaked at various times, mostly 5f - Hybrid granite gneiss along a belt extending northeast from Valley Lake to Dead Otter Lake. 5g - Hematitized, albitized granite gneiss Extensive new staking was done in the spring of 1965 in the area north, south, and west of Dotted and Dead Otter Lakes. In 1965 most of the ground Intrusive Contact between Dotted Lake, Theresa Lake and the Black River was covered by staking. In 1962 McIntyre Porcupine Mines Ltd. surveyed and drilled a 52 claim area MAFIC AND ULTRAMAFIC INTRUSIVE ROCKS enclosing the Von Klein (No.3) copper-nickel showing just east of Summers 4a - Amphibolitic metagabbro Lake on Highway No. 614. In 1963, some drilling was done by Mining Corpo• 4b - Serpentinite ration of Canada Ltd. in the area between Amwri Lake and the Black River 4c - Gabbro about ½ to 1 mile east of the river and in late 1963 T. and W. Kusins un• 4d - Talcose rock (dikes) covered a lead-zinc showing (No.2) between the Black River and Valley Lake, 4e - Anorthositic gneiss about ¾ mile west of the river. The Kusins showing was examined in I965 by Cominco. In January 1966 Caravelle Mines Ltd. held a large block of Intrusive Contact more than 100 claims enclosing the Von Klein copper-nickel showing and extending from Theresa Lake in the east to Highway No. 614 on the west, south METASEDIMENTARY ROCKS of Dead Otter Lake. Also, Irish Copper Mines Ltd. held two blocks of claims north of Dotted Lake enclosing a zinc showing (No.4) staked by B. Fairservice. 3a - Conglomerate and finely laminated Both companies flew geophysical surveys during the summer of 1965 and follow- greywacke 3b - Pyritic and (or) muscovite-quartz-feldspar up work is continuing. gneiss 3c - Biotite-quartz-feldspar paragneiss General Geology: The northern half and western parts of the area are under• 3d - Feldspathized or migmatitic metasediments lain essentially by granite gneisses and younger massive granitic rocks or tuff intruding these gneisses. The younger massive granitic rocks (6) have a 3e - Garnet-biotite schist relatively high magnetic response and the general outline of intrusions of 3f - Kyanite-garnet-quartz-feldspar gneiss this material can be determined from aeromagnetic maps (Maps 2157G, 21586. 3g - Meta-arkose and 2168G). In the southeast quarter of the area east of the Black River, INTERMEDIATE TO SILICIC METAVOLCANICS, the rocks consist of a folded series of biotite-quartz-feldspar paragneisses, PYROCLASTIC ROCKS AND METASEDIMENTS conglomerates, hornblendic metatuffs and metavolcanic hornblende gneisses intruded by serpentinite, amphibolitic metagabbro, and massive granitic 2a - Porphyritic dacite (flows) rocks. The metasedimentary and metavolcanic rocks extend as a narrow 1 ½ 2b - Dacite flow breccia mile wide belt from south of Valley Lake, northeastwards to Highway No. 614 2c - Pillow lava where the belt swings east and widens to about 6 miles due to folding of 2d - Rhyolite breccia the metavolcanic rocks on the north side of the belt. These rocks strike- 2e - Metarhyolite eastwards between Highway No. 614 and Theresa Lake and chen swing southeast 2f - Intermediate to silicic welded tuff through White Lake to Highway No. 17. The flow rocks are predominantly or flow breccia mafic hornblendic gneisses of formerly pillowed basaltic or andesitic 2g - Agglomerate, tuff, greywacke 2h - Iron formation character. Porphyritic dacite pillow lavas occur west of the railroad track 2j - Biotite gneiss around Pinegrove Lake and dacitic flow breccia, rhyolitc breccia, metarhyo— 2k - Migmatite lite, tuff and agglomerate are exposed south of the amphibolitic metavolca• nic rocks, east and southwest of Summers Lake. Tron formation, which gives MAFIC TO INTERMEDIATE METAVOLCANIC ROCKS rise to a strong magnetic anomaly is exposed on the northwest side of the mafic metavolcanic ridge between Amwri Lake and the Black River and on the la - Medium-to fine-grained, massive and southeast side of this metavolcanic ridge, a band of pyritic muscovitic meta- gneissic amphibolite arkose extends from west of the Black River east to Phil Lake. The pyro- lb - Medium-to coarse-grained, massive and clastic facies terminate just east of Theresa Lake and the mafic metavolcanic gneissic amphibolite rocks then lie in contact with conglomeratic metasediments to the south. 1c - Laminated hornblende gneiss The metasedimentary and metavolcanic rocks are intruded by granites, meta- 1d - Pillow lava gabbroic amphibolite sheets, serpentinite lenses and feldspar porphyry, 1e - Hematitized, epidotized metavolcanic rock amphibolitic, and dacite" dikes. Large lenticular bodies of serpentinite 1f - Migmatite are exposed at three locations; on the northeast shore of Dotted Lake, at the north end of Theresa Lake, and in Spruce Bay on the west side of White SYMBOLS FOR P. 332 - P. 335 Lake. All these bodies give rise to marked magnetic anomalies (Map 2168G). The youngest rocks in the area appear to be the diabases which form dikes Muskeg or swamp. Strike and dip of intruding all the previously mentioned formations. schistosity. \ Structure: The metasedimentary-metavolcanic belt of rocks represents the River, creek, stream, southern limb of a roughly east-northeast trending anticlinorium. The south R = rapids; F = falls. Strike of vertical side of the belt consists of metasediments and in this section the anticlinal schistosity. limb is slightly overturned to the south. The metavolcanic section on the Railway. north side of the belt is thickened by repetition caused by folding about an east-northeast trending anticline centred on Dead Otter Lake and a para• Strike and dip of gneissosity. llel syncline lying on the north side of Dotted Lake. These folds plunge Electric power transmission westwards, the plunge being about 20° near Roger Lake and steepening west• 1 ine. Strike of vertical wards to almost vertical at Highway No. 614. At the north contact of the gneissosity. metasedimentary-metavolcanic belt the foliation of the granite gneisses dips steeply south beneath the metavolcanic rocks but progressing north• Highway. wards the dips gradually shallow until, about 2 miles north of the contact Horizontal gneissosity. the dips are very shallow and in many places horizontal. The flat dip of Trail, portage, winter road. the foliation persists northwards to within 3 miles of Manitouwadge where Stratiform foliation, dip the foliation starts to dip predominantly north between 30° and 70°, unknown. beneath the metavolcanic rocks of the Manitouwadge syncline. Glacial striae. Economic Geology: The biotite-quartz-feldspar paragneisses of the Black Lineation (plunge known, River area are similar in appearance and composition tot the metasedimentary Drift features. plunge unknown). gneisses of the Manitouwadge area. Unlike the Manitouwadge area, however, iron formation is relatively rare and was found in only two localities; one between Amwri lake and the Black River, close to the granite contact and Small rock outcrop. Drag-folds. (Arrow indicates the other in the region of the Von Klein copper-nickel showing (No.3). direction of plunge). Both these occurrences contain pyrite and pyrrhotite. The most economically Boundary of rock outcrop. interesting feature in the area is a band of predominantly pyroclastic material, associated with some siliceous metasedimentary and intermediate Wide shear zone. to acid flow rocks, which extends from midway between Valley Lake and the Geological boundary, defined. Black River, east-northeastwards for about 6 miles to Highway No. 614, Fault, indicated or assumed. just south of Summers Lake, then eastwards to north of Musher Lake and southeast to Theresa Lake. The rocks in this band are characteristically Geological boundary, garnetiferous hornblende metatuffs and agglomerates, siliceous biotite approximate. Lineament. gneisses, and muscovite gneisses frequently high in pyrite. The lead-zinc showing of T. and W. Kusins (No. 2) is in metavolcanic hornblende gneiss at the southwest end of this band. Silicified, pyritic, northeast-trending Geological boundary, assumed. Location of mining property. zones occur in the hornblende gneiss and in one of these, small pods of sphalerite and galena occur with the pyrite. T. and W. Kusins report that Geological boundary as indi• Building. a grab sample gave on analysis 1.93 per cent zinc, 0.94 per cent lead and cated by geophysical data. 0.64 oz. silver per ton. A major fault trending N65°W is believed to occur about 1,000 feet southwest of the showing. Gravel pit. Strike and dip; direction The Von Klein copper-nickel occurrences (No.3) are located of top unknown. about halfway along the pyroclastic band about 1½ miles northwest of Drill hole, inclination unknown. Musher Lake. The rocks in the vicinity of the showings are acid to inter• Strike and vertical dip; mediate flow rocks, breccias and pyroclastic rocks intruded by dacitic direction of top unknown. feldspar porphyry, biotite granite, muscovite granite and talcose ultra- basic dikes. There are several sulphide showings and, in what appear to be Network of quartz veins. the two richest zones, chalcopyrite-pyrrhotite-pyrite mineralization seems Direction in which lava flows to be confined to two separate, large blocks of coarse-grained amphibolite; face as indicated by shape of Sulphide mineralization. one apparently is rafted in a rhyolite breccia (2d) plug and the other is pillows. in rhyolite or acid welded tuff (2fg). Mineralization in the surrounding muscovite-biotite gneisses is minor. Some other showings with copper-nickel Magnetic attraction. values occur in shear zones in the mafic pillow lavas (la) and garnetiferous Synclinal axis. agglomerates (2g) on the north side of the pyroclastic band. A geological Dikes. map of a 52-claim block was prepared by McIntyre Porcupine Mines Ltd. in Anticlinal axis. 1962 and some drilling was done at that time. The drilling was concentrated mainly on the two main surface showings and this indicated little continuity Firetower. to the mineralized amphibolite blocks. A number of electromagnetic anoma• Direction of plunge of fold lies unrelated to the two main showings were noted but these were examined axis, crest line or trough only superficially. In 1965 Caravelle Mines Ltd. outlined several more line. electromagnetic anomalies and considered that these might relate to the shear zone type of mineralization on the property. This investigation is MINERAL OCCURRENCES REFERENCE continuing. Cu . Copper Pb Lead cp Chalcopyrite py Pyrite A small zinc showing (No.4) was located by B. Fairservice in mo Molybdenite po Pyrrhotite the mafic metavolcanic hornblende gneisses north of Dotted Lake and this Ni Nickel Zn . Zinc property was under examination by Irish Copper Mines Ltd. in I965. The showing consists of 3 or 4 seams of massive sphalerite up to 1 inch in width in a short rusty shear zone up to 4 feet wide and about 50 feet long. No LIST OK PROPERTIES other mineralization was noted in the locality except for minor pyrite in some quartz feldspar porphyry dikes which intrude the hornblende gneisses. 1. Mining Corporation of Canada Ltd. (1962). 2. Kusins property (Cominco 1965). 3. Von Klein property (Mclntyre Porcupine Mines Ltd. 1962; Traces of mineralization were noted in three other localities. Carabelle Mines Ltd. 1965). On Highway No. 614 and on the railroad track opposite the north end of East 4. Fairservice property (Irish Copper Mines Ltd. 1965). Barbara Lake a narrow band of massive and laminated metagabbro is inter- layered with the paragneiss. Disseminated pyrite is noticeable in the coarse-grained metagabbro on the railroad track and on Highway No. 614- SOURCES OF INFORMATION The laminated metagabbro outcrop on the east side of the road is cut by a thin 1-inch to 4-inch seam of black earthy weathered material containing Geology by V.G. Milne and assistants 1964, 1965. pyrite. A second small showing was located on the Ontario Paper Company Assessment file No. 63-1210, Ontario Dept. Mines. road opposite the north end of Morely Lake. The road cuts through a small Ontario Dept. Mines, Vol. XXXI, 1932, pt. 6 outcrop of amphibolite metagabbro in a generally drift-covered area. The Ontario Dept. Mines, Vol. LXVI, 1957, pt. 8. amphibolite contains a little disseminated pyrite and is cut by scattered, Geological Report on the Hemlo area, Dept. of Industrial Development, thin, rusty fractures containing occasional small blebs of pyrite. On the Canadian Pacific Railway, 1957- west side of the road a loose block blasted from the outcrop shows local shearing along a rusty fracture and associated with this a small 4 to Base map from maps of Forest Resources Inventory, Ontario Department of 6-inch diameter pod of massive pyrrhotite, chalcopyrite and pyrite. The Lands and Forests, with additional information by V.G. Milne. third locality is a small outcrop of garnetiferous amphibolite on the Ontario Paper Company road east of the south end of Agonzon Lake. Widely scattered, thin, rusty pyritc-coated fractures cut the rock and locally a Issued 1966. thin veneer of molybdenite coats the fractures.