RP 271(A) PRELIMINARY REPORT ON FANCAMP - HAUY AREA, ABITIBI-EAST COUNTY PROVINCE OF QUEBEC. CANADA

DEPARTMENT OF MINES

GEOLOGICAL SURVEYS BRANCH

PRELIMINARY REPORT

ON

FANCAMP-HAÜY AREA

ABITIBI-EAST COUNTY

BY

STANLEY W. HOLMES

QUEBEC 1952

P. R. No. 271 PRELIMINARY REPORT ON FANCAMP-HAY AREA ABITIBI-EAST COUNTY

by

Stanley W. Holmes

INTRODUCTION

Location

The Fancamp-Haify area, mapped by the writer during the summer of 1951, lies in Abitibi-East county, about 280 miles slightly west of north of Montreal and some 20 miles southwest of Chibougamau lake. It comprises an area of approx- imately 200 square miles, bounded by latitudes 49030' and 49045' and by longitudes 74030' and 74045'. It includes most of Fancamp and Hady townships, the eastern parts of Brongniart and Rasles, and narrow strips of Scott and Levy townships. The area is immediately west of the one mapped by Imbault (1) in 1950.

Means of Access

The cheapest and most convenient means of access to the area is via the St. Félicien-Chibougamau highway which passes about four miles east of the north- eastern corner of the map-area. From the highway, the area may be easily reached by either of two canoe routes. The easier of these, starting from Perron lake at mileage 121.4 on the highway, follows westward through Lauraent, La Dauversière, Le Royer and Chevrier lakes, in the Queylus area (2), to Fancamp lake in the south- eastern part of the present map-area. This route' is interrupted only by two por- tagg each about 1,000 feet long. The other route begins at mileage 129 on the highway and leads southwestward through Calmor and Chevrier lakes to Fancamp lake. Only three, well-cut portages, the longest three-quarters of a mile, break this route. Aerial transportation to the area is provided by several companies with bases conveniently located on Chibougamau or La Blanche lakes.

Topography

The map-area lies a few miles west of the height-of-land between the St. Lawrence River and James Bay drainage basins. The general elevation is ap- proximately 1,200 feet above sea-level. The area is gently rolling terrane, largely

(1) Imbault, P.E., Preliminary Report on the Queylus Area, Abitibi-East and Ro- berval Counties; Que. Dept. Mines, P.R. No. 250, 1951. (2) Imbault, P.E., op. cit.

M-2935

- 2

covered with glacial deposits except for a few hills along the northern and east- ern shores of Muscocho lake which rise about 150 feet above the lake level and may be seen for many miles around.

In the extreme northeastern corner of the map-area, as well as along the eastern shore of Fancamp lake and around Verneuil lake, drumlins and low drum- linoid hills are common, and the resulting topographical lineation is striking. In general, however, the areas underlain by granite are rolling and hummocky, whereas those underlain by volcanics are characterized by elongated low ridges.

About one-quarter of the map-area is covered by bodies of water which drain eventually into James bay.

GENERAL GEOLOGY

All the consolidated rocks seen in the area are Precambrian in age. They include: (1) a series of Keewatin-type flows containing numerous interbeds of tuffaceous and agglomeratic material; (2) a possibly younger group of feld- spathic sedimentaries, arkose, slates, coarse agglomerates, and conglomerates; (3) sills and bodies of basic to intermediate, composition intruding the rocks of the first two series; and (4) granitic and dioritic massifs intruding all the other types of rock.

Table of Formations

Recent CENOZOIC :.x_d Clay, sand, gravel Plei •cocene

Great unconformity

Verneuil granite Museocho granite Post-Keewatin Eau Jaune Lake complex: quartz diorite. diorite, feldspar porphyry

EARLY_ Intrusive contact PREC.ZO3RI.AN Gabbro. c? iorite Late- orost Intrusive contact Keewatin (7)P FeldsDar•-rf..ch sodzmentaries or tuffs, con- gL,;-3rate., aggi~.. xate, arkose, slate, • Keeuatin-tyre Basalt a. .. 3*x3.e5? ?e flcws, tu-`:f5, agglom- erate, r.ri..or be.:.:.c in„ ~ïves - 3 -

Keewatin-type Rocks

About three-quarters of the map-area is underlain by Keewatin-type vol- canic and pyroclastic rocks, with minor basic intrusives. Although commonly in- timately interbedded, these volcanic flows and pyroclastic rocks can be grouped, as shown on the accompanying map, into belts in which one type definitely predom- inates over the other. It should be kept in mind, however, that within the mapped belts of lavas there are many exposures of pyroclastics, and vice versa.

Volcanic Flows

Andesitic and basaltic lavas with minor basic intrusives and pyroclas- tics crop out in three main belts and in a very small zone in the extreme north- east corner of the map-area. The northernmost belt, ranging it width from three and a half miles to half a mile, trends east-southeast across the entire northern part of the area. Another belt, trending more or less northeast, occupies a tri- angular-shaped area (except for the Muscocho and Eau Jaune Lake intrusive bodies), with base along the western boundary of the map-area and apex at the northeast end of Muscooho lake. -The third large belt consists also of a triangular-shaped area with base along most of the southern boundary of the map-area and apex at Baker lake, about four miles to the north.

The rocks of the northernmost belt are mainly andesites and basalts with numerous thin tuffaceous horizons. The flows are highly altered and ones of intermediate composition predominate. These are light coloured rocks in which well-developed pillow structures are common. At many places the pillows have ve- sicular borders. The massive andesitic flows show, here and there, a porphyritic texture.

Pillowed and massive basalts predominate in the central belt in which little andesite was seen. Tuffs and coarse agglomerates are also abundant in this zone.

The rocks of the southernmost belt are similar to those of the northern one in that the assemblage consists of andesites and basalts, with andesitic flows in predominance. Minor tuffs also are found here.

The primary structures and textures of the lavas are, in general, fair- ly well preserved except in areas of shearing and in the vicinity of intrusive igneous masses.

Many of the pillowed flows were useful for top determinations, especial- ly in the basaltic lavas. A very irregular and jumbled type of pillow character- izes many of the intermediate flows, and, even though the pillows are well formed, top determinations are not possible in them. It is not uncommon to find that many of the pillows in the andesitic flows have had their central parts completely re- placed by lighter, more felsic material.

Pyroclastics

Rocks that are shown on the accompanying map as mainly pyroclastics underlie irregular bands of varying width between the three belts of,lavas and, -4 -

in places, between the lavas and other rock types. The pyroclastics can be di- vided into two main groups - fine- to medium-grained tuffs, and coarse agglomer- ates.

The tuffs, in places, display a well-developed banding or bedding, are well sorted,. and are probably water-lain. In many places, however, they are mas- sive and poorly sorted, and may easily be mistaken for massive flow rocks.

Tuffs of the first type crop out abundantly on the islands in the north- ern part of Fancamp lake where a series of well-banded tuffs strike northeast along the northern contact of the Verneuil stock.

The massive variety of tuff that shows no banding or bedding is found at many places throughout the map-area. Close examination of the rock usually reveals that it contains small angularrfelsic fragments which is the only crite- rion by which the rock is identified.

Coarse-grained agglomerates and fragmental rooks are seen at various places throughout the area but are best exposed on a small island in the north- eastern part of Muscocho lake. Here a large band of agglomerate containing well- sorted, rounded, cream-coloured fragments up to two inches in diameter is found interbedded with massive basalts. The fragments stand out in relief against a dark green groundmass, and all are slightly elongated. This agglomerate is ap- parently water-lain.

Another zone of very coarse agglomerate containing fragments up to twelve inches long and four wide is well exposed on the southern shore of Chico lake. On these outcrops the fragments, which appear to be felsic in composition, stand out in striking contrast with the darker groundmass.

Late- or Post-Keewatin (?) Sedimentary Rocks

Exposures of positively water-lain sedimentary rocks are found scat- tered in a two,.n1 a half mile wide, southeasterly trending belt in the northeast corner of the map-area.

These rocks belong to two main types, a fine- to medium-grained feld- spathic series,. and very coarse agglomerates and/or conglomerates.

The feldspathic series forms a usually well-bedded assemblage of typi- cal sedimentary appearance. The rocks are generally made up of acidic volcanic material and have a high content of feldspar with quartz in minor amount. They are probably for the most part water-lain tuffs. They vary from a light-weather- ing, aphanitic rook to a darker grey, medium-grained, feldspathic arkose. The aphanitic rock is probably a rhyolitic tuff, although it has, in places, the mas- sive appearance of an acidic flow.

Associated with this feldspathic series, although in lesser abundance, are bands of agglomerate or fragmental rocks. The fragments, which range up to four inches, consist for the most part of acidic and basic material and are set in a tuffaceous groundmass. - 5 -

Zones of boulder conglomerate up to 30 feet wide were found at several places within this series. The best exposures are seen along the portage that leads from the northeastern part of Muscocho lake to Merrill lake. Because of their irregular and discontinuous distribution within different horizons, they are thought to have been laid down intermittently during the deposition cf the feldspathic sediments. However, they appear to be most common at the base of the feldspathic series immediately above the Keewatin-type tuffaceous and fragmental volcanics.

These conglomerates are composed of granite boulders, up to eighteen inches in size, with a few boulders of basalt and felsic pebbles, all set in a tuffaceous matrix. The composition of the matrix suggests that the conglomerates were formed during periods of volcanic activity, contemporaneous with the forma- tion of the feldspathic sedimentary rocks. Most of the boulders have been stretched to several-times their original length and are oriented parallel to the strike of the formations.

Rocks of probable sedimentary origin crop out in a small wedge-shaped zone northwest of Fancamp lake. These rocks consist of a thick series of agglom- erates and tuffs, with interbedded arkose, slates and grit.

Late- or Post-Keewatin (?) Intrusive Rocks

As elsewhere in the Temis.oamian sub-province, the Keewatin-type vol- canic rocks of the area are intruded by numerous dioritic and gabbroic bodies, many, no doubt, genetically related to the lavas of the district.

Most of these bodies are in the form of sills or concordant lenticular masses and are too small to be shown on the accompanying map. One, however, is much larger and is mapped separately. It extends along the eastern border of the map-area from the northern part of Fancamp lake northward for some three and a half miles, and is apparently discordant with the adjacent formations.

These intrusive rocks are massive with the exception of some that have been sheared and metamorphosed into a talc-chlorite schist. On weathered surfaces they are usually light to dark brown with a few varieties altering to a rock with a white and green mottled surface. Most of these intrusives are medium-grained and have a somewhat talcose appearance on fresh surfaces.

Post-Keewatin Intrusive Rocks

Muscocho Stock

'A ten-square-mile, roughly circular, granitic body is thought to under- lie most of Muscocho lake and the large peninsula that separates the two arms of the lake. In places it forms low hummocky hills that rise gently above the sur- rounding' Country.

The granite of this body is made up essentially of quartz, hornblende, feldspar, and a little biotite. The rock appears to be fairly uniform in compo- sition and structure. It is medium.-grained and massive except at one place just - 6 -

north of Muscocho lake where, near its contact with schistose volcanic rocks, a poorly-defined banding has developed. Many inclusions of greenstone are found in the granite. They are unoriented and are generally recrystallized to hornblende schist.

The stook has steeply-dipping joints striking northeast and southeast. In the central part of the stock, flat--lying joints striking in a northwesterly direction are abundant. Hydrothermal minerals cover most of the joint surfaces. Numerous granitic and porphyritic dykes believed to be genetically related to the Muscocho granite cut the volcanics throughout the map-area.

Verneuil Stock

The Verneuil stock, in the southeastern part of the map-area, occupies a roughly-triangular area of approkimately thirteen square miles. The rock is essentially a quartz-biotite granite and is very uniform in composition throughout the whole stock. The granite is usually medium-grained and very massive. It contains-many inclusions of recrystallized volcanics, some of which have weathered out leaving small pockets.

There is evidence that the emplacement of the magma was at least par- tially controlled by a pre-intrusion fault that crosses the area in a northeast- erly direction causing the straightness of the northern contact of the stock.

The Verneuil stock has steeply-dipping joints striking north and north- west. The joints usually have a coating of hydrothermal minerals. A few aplitic dykes and barren quartz veins were observed cutting the granite.

Eau Jaune Lake Complex

This complex occupies some ten square miles in the southwestern part of the map-area. It underlies the southern part of Eau Jaune lake and extends southwestward across the western limit of the area.

The rock of the complex may be classed as hybrid, since many different facies make up the massif. The greater part of it, however, consists of medium- grained, fairly massive quartz diorite, grading in places into a fine-grained rock of the same type, or into a porphyritic variety in which well-developed feldspar phenocrysts occur in a groundmass of"dark aphanitic material, commonly with tra- chytic texture. The porphyritic facies is commonly found along the outer margin of the mass. It appears to be mainly a feldspathization contact phenomenon.

The fact that the complex varies considerably in composition from place to place suggests that the entire exposed mass is the outer contact _zone of a deeper-lying granitic body. This opinion is supported by an abundance within the complex of large remnants of country rock, usually in a recrystallized or partly assimilated state.

The complex may be genetically related to the Muscocho granite as sug- gested by the proximity of the two rock masses, and also by the similarity in composition between certain facies of the complex and the border facies of the Muscocho stock. 7

STRUCTURAL GEOLOGY

Folds

In the Keewatin-type lavas and pyroclastics, the schistosity seems ev- erywhere to be parallel to the flows and bedding.

In the southern half of the map-area these Keewatin-type rocks have a general northeasterly trend. Farther northward, however, the trend becomes east- erly, and, in the northernmost belt of pyroclastics, the bedding and schistosity strike somewhat south of east. In the belt of sedimentary rocks of the north- east corner of the map-area, the bedding and schistosity trend. southeasterly.

Some local divergencies in strike are attributable to the influence of some of the younger intrusive masses. One can readily notice, in particular, that the schistosity and bedding of the Keewatin-type rocks curve completely around the Muscocho stock. Likewise, in the narrow, southeast-trending belt of pyroclastics south of the Verneuil stock, the bedding strikes southeasterly par- allel to the outline of the granitic body.

Throughout the map-area the formations dip steeply to vertically, and it is evident that they have been tightly folded. The locations of the fold axes can, however, be little more than speculated upon.

At a number of places in the lavas, well-preserved pillows permit the determination of the direction in which the flows face. In the northern part of the northernmost belt of lavas, several determinations indicate that the flows here all face north and nearly uniformly dip vertically. Farther south, in the adjacent pyroclastics and also in the central belt of lavas, a number of top de- terminations were made, and these formations face southward. This evidence would seem to indicate the presence of an anticlinal fold, whose axis might run more or less eastward and southeastward through the northern belt of lavas. Some addi- tional support for this hypothesis was obtained from criteria (described below) suggesting that the belt of sedimentary rocks in the northeast part of the map- area occupies a synclinal structure. On one exposure of finely-banded sedimen- tary rock half a mile north of mile-post six of the Haily-Scott township line, well-preserved cross-bedding indicates that the tops of the beds are to the north. Along the Merrill Lake portage, coarse conglomerate beds give way northeastward to a finer-grained series of feldspathic sedimentary rocks. This, also, would seem to indicate that the beds here face north. This somewhat meagre evidence suggests that the sedimentary belt lies on the southern limb of a syncline, that is, on the northern limb of the anticline postulated above.

The V-shaped belt of pyroclastics opening outward in a west-southwest direction from its apex east of Muscocho lake suggests a plunging fold structure. If this were so, however, the formations on the limbs might be expected to have lower dips than the near-vertical positions they do occupy. The southward-facing beds just north of Muscocho lake would indicate a syncline plunging southwest- ward. Two miles north of Winchester lake, however, the beds were found to face south, which evidence is not in harmony with such a structure. On the other hand, an anticlinal structure plunging northeastward is not supported by the evidence available. - a -

Faults and Shears

A pronounced zone of faulting crosses the southern part of the map- area in a northeasterly direction. This is the Fancamp Lake fault which is clear- ly defined on the islands and shores of the northern part of Fancamp lake where outcrops are very abundant. In the drift-covered southwestern part of the area its presence is not marked by any well-defined structure, except possibly the alignment of several small lakes. On that section of Opawica river just off the boundary of the map-area to the southwest, there is a broad zone of intense shear- ing that is on strike with the fault passing through Fancamp lake. On this lake, the fault is indicated by two clearly-defined, nearly parallel zones, less than a mile apart, which are believed to merge into one at the western edge of the lake. These zones are marked by intense shearing, breociation, mylonitization, extensive dragging, and a well-defined topographic alignment. An iron-rich car- bonate is particularly abundant where the rocks have been highly sheared in zonas of strong movement along the faults. Where the brecciated rocks are cemented by this carbonate it has, in places, weathered out leaving a porous rusty-brown ma- terial. At several places on islands in Fancamp lake the tuffs have been pulver- ized into microbreccia or mylonite. Along the northwest shore of Baker lake, southwest of Fancamp lake, the tuffs are oriented in a northeasterly direction whereas on its southeastern side the formations strike southeasterly. Dragging and shearing indicate that there has been some movement here.

It is quite possible that the Fancamp Lake fault is the southwestern extension of the Taché Lake fault of the Chibougamau Lake region to the north- east, with which it lines up. If this assumption is correct, the country adja- cent to and between these two fault zones should be favourable for prospecting.

Another zone of faulting, striking parallel to the Fancamp Lake fault, is seen on Obatogamau river, just south of its outlet into Muscocho lake. It is marked on both sides of the river by brecciated basalt cemented with brown car- bonates along a belt of intense shearing.

Similar breccia is found along the outlet of Eau Jaune lake. At one place it is more than 50 feet wide and it has been seen at places along the strike es much as several thousand feet apart, which would seem to indicate that another important fault is marked here.

Numerous other small local zones of shearing were seen at various places throughout the area. Most of these are parallel to the regional trend, but a few cut across the structure. Many of them are mineralized with classy quartz and small amounts of sulphides.

ECONOMIC GEOLOGY General Statement

Since the fall of 1949, a considerable amount of staking and prospect- ing has been carried out in the map-area. This activity resulted from the rushes started in the Queylus area (1) to the east in 1949 and 1950. Interest was

(1) Imbault, P.E., op. cit. - 9 -

:increasedby the discovery, in 1950; of gold in a large zone of shearing about half a mile south of Chico lake. Almost all of Fancamp and Hatiy townships have been staked, as well as parts of the other townships of the map-area.

Previously however, in 1936, Noranda Mines, Limited, and McKay (Quebec) Exploration, Limited, carried on preliminary development work on several base metal showings on Eau Jaune lake, and considerable staking took place at that time.

There are two principal types of mineralization in the map-area - gold and base metal.

Gold

Within the present area, the most favourable host rock for gold min- eralization appears to be the tuffs, especially where they are sheared. At many places, sheared and crumpled tuffaceous bands are cut by quartz veins containing small amounts of sulphides, mainly pyrite, and the noses of small drag folds in the tuffs are, in many instances, occupied by veins or blebs of quartz. A local silicification of the adjacent wall rock usually accompanies this mineralization and, in some places, the silicified wall rock carries gold values. Tourmaline and a light brown carbonate, probably ankerite, are commonly associated with the quartz and sulphides, and most of the gold appears to be closely related to this tourmalinization and carbonatization.

The tuffaceous formations were apparently the most incompetent rocks and shearing and crumpling of them resulted in suitable channels for the passage of mineralizing fluids. The other rock types, especially the lavas, are, however, not necessarily unfavourable host rocks for gold deposits, and should not be over- looked by the prospector, especially where they are sheared and mineralized.

Description of Mining Properties Teck Exploration Company, Limited

This company holds several groups of claims around Fancamp lake. The first gold discovery in the map-area was made on one of these groups, at a .point about half a mile south of Chico lake (1)31. Some preliminary development work has been done on a mineralized zone at the contact between the Verneuil granite and a broad baud of tuffs and small basic sills. Trenching here has exnacsd sheared and crumpled-tuffs on the limbs of a small drag fold that has boon exten- sively mineralied, -especially at the nose, with quartz, tourmaline, carbonate, and some sulphides, mainly pyrite, with associated gold. An aplitic dyke, pre- mineralization in age and probably related to the Verneuil granite, cuts across the nose of this small drag fold.

Other trenches in the immediate vicinity show sheared, silicified and, in places, crumpled tuffs cut by small quartz veins carrying varying amounts of pyrite. Tourmaline and carbonates are not visible, however, and it seems that

Numbers within brackets correspond to showings indicated on the accompanying map. - 10 - most of the gold occurs in the mineralized wall rock, as the quartz veins are of the glassy, barren variety.

The second mineralized zone (2) on which the company has done devel- opment work is about 3,000 feet northwest of the original discovery. The showing is in a band of tuffs that has been much sheared along the strike. The shear zone is mineralized at different places for a length of about 4,000 feet, with widths up to 75 feet. A granitic dyke and a glassy white quartz vein have been injected along the shearing and the adjacent tuffs have been silicified and min- eralized with sulphides, mainly pyrite, with associated gold. Eight trenches have been put down at intervals across the strike of this zone.

Mining Corporation of Canada, Limited

This company holds a group of claims adjacent to and northeast of Teck Exploration Company's ground. Some preliminary development work has been done on a mineralized zone (3) that appears to be the extension of Teck Exploration's original showing (1).

A band of tuffs that parallels the contact with the Verneuil granite has been extensively sheared and crumpled. Quartz, abundant carbonates, tourma- line, and some sulphides have been deposited in the rock. Small gash veins.. of quartz with associated tourmaline and sulphides cut through zones of abundant carbonates. It appears that the gold mineralization is associated with these veins. The overall character of the mineralization is essentially the same as on the Teck Exploration's showing (1) where tourmaline is also present. In one pit, a feldspar porphyry dyke is seen intruding the tuffs which have been silici- fied and, in places, abundantly mineralized. This alteration has given the tuffs a dense massive appearance but their banding is generally well preserved despite their alteration and deformation.

Mining Corporation also holds another group of claims (6) in the north- ern part of the map-area along the eastern shore of Eau Jaune lake. Here, sheared andesites and tuffs are mineralized with quartz, tourmaline, carbonate, and some sulphides. The presence of gold associated with this mineralization has been reported.

Calmor Mines, Limited

This company holds a group of claims (7) near Eau Jaune lake, just east of those of Mining Corporation. The rocks of the property consist of a se- ries of sheared tuffs and andesites that have been silicified and mineralized with small amounts of sulphides carrying some gold. Several porphyry dykes in- trude the volcanics. The claims were staked at the close of summer, 1951, and only a small amount of work had been done at the time of the writer's visit.

Base Metals

The base metal mineralization of the area is generally found in the basaltic or gabbroic rocks. In the two occurrences studied in detail, barren quartz veins and granitic and porphyritic dykes were found in the zones of mineralization. The various deposits range in size from small rusty patches to large scale replacements of the country rock, some being up to 60 feet wide and hundreds of feet long.

Pyrrhotite, chalcopyrite and pyrite are the most common sulphides of these zones and they replace the country rock entirely or in part. A rusty cap or gossan, derived from oxidation of the sulphides, is an aid in prospecting for them.

Description of Mining Properties Noranda Mines, Limited

This company has done some preliminary development work on two base metal showings in the area. The larger of the two (4) is within a group of 15 claims or. a large island in the central part of Eau Jaune lake. The smaller (5), which is also within a group of 15 claims, is on a small island in the extreme northeastern part of Muscocho lake.

The main showing (4) is a sulphide replacement of massive basalt and gabbro at scattered intervals along their strike for approximately 5,000 feet. The mineralization, chiefly pyrrhotite with a little chalcopyrite, is very spot- ty, but in places forms lenses up to 30 feet wide. Some of the mineralized zones consist merely of disseminated sulphides whereas the replacement has been total in others. The sulphides weather readily and most of the deposits are capped with a rusty gossan. The mineralized rock is very dense and hard to break. This zone of sulphides lies on the contact between the Eau Jaune Lake complex and the Keewatin-type rocks, a fact which suggests that the mineralization is related to this intrusive. Apart from this contact zone, the only other apparent structural control is a minor local slicing of the massive basalt parallel to the strike of the flows.

The other showing (5) of the company is about 40 feet long and several feet wide, and shows a similar type of mineralization, that is, massive gabbro replaced by sulphides. At this showing, a small granitic body intrudes the gab- bro, and the sulphides are localized around this intrusive. The sulphides, main- ly chalcopyrite and pyrrhotite, occur either separately or together and replace the recrystallized gabbro in irregular small zones.

In 1948, the company carried out a stripping, trenching, and drilling program, along with some geophysical work, on the above-described properties. It appears that the results obtained did not warrant further development work at the time.

Recommendations

In addition to the property showings described above, some sulphide mineralization was noted here and there throughout the map-area. The writer be- lieves that further careful prospecting might result in the finding of other de- posits - either gold or base metal - of potential economic interest.