NORTH SHORE of the SAINT-LAWRENCE from AGUANISH to WASHICOUTAI BAY, SAGUENAY COUNTY PROVINCE of QUEBEC, CANADA Department of Mines Honourable C
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RG 043(A) NORTH SHORE OF THE SAINT-LAWRENCE FROM AGUANISH TO WASHICOUTAI BAY, SAGUENAY COUNTY PROVINCE OF QUEBEC, CANADA Department of Mines Honourable C. D. FRENCH, Minister A.-O. DUFRESNE, Deputy Minister GEOLOGICAL SURVEYS BRANCH I. W. JONES, Chief GEOLOGICAL REPORT 43 NORTH SHORE OF THE SAINT-LAWRENCE FROM AGUANISH TO WASHICOUTAI BAY SAGUENAY COUNTY by Jacques Claveau QUEBEC RÉDEMPTI PARADIS PRINTER TO HIS MAJESTY THE KING 1950 Ministère des Richesses naturel:es du Qu{bec 1 :iEIiVICE DOCUMENTATION TE~1i, tcà.3~: TABLE OF CONTENTS Page INTRODUCTION 1 Location of area 1 Means of access 1 Previous work 1 Field work 2 Acknowledgments 3 DESCRIPTION OF THE AREA 4 Topography 4 Vegetation 6 Settlements 6 Industry 7 TABLE OF FORPMATIONS 8 GENERAL GEOLOGY 9 PETROLOGY 13 Sedimentary rocks 13 Gneisses 14 Banded gneisses 14 Granitic gneiss 16 Quartz-dioritic gneiss 17 Basic rocks 19 Granitic intrusives 22 General statement 22 Gneissic granite with occasional augen facies 22 Microperthite granite 23 Small masses and dykes of pegmatite and granite 24 Prehnite rock 25 STRUCTURAL GEOLOGY 25 ORIGIN OF THE BASAL COMPLEX 28 Summary 31 GLACIAL GEOLOGY 32 ECONOMIC GEOLOGY 33 Fluorite 33 Graphite 33 Iron sands 33 Magnetite 35 Pyrite 35 CONCLUSIONS 36 MAP AND ILLUSTRATIONS Map No. 819.— Geology of the North Shore of the Gulf of St-Lawrence, Aguanish to Vashicoutai Bay...(in pocket) Plates I-A and B.— Terrace of Champlain age near Aguanish. II-A and B.—Terrace of Champlain age near Natashquan. III and IV.— Parts of the Natashquan terrace re-worked by the wind into dunes. V-A. —Aspect of the shore two miles east of Michon Village. B.—View near the entrance to Natashquan harbour. VI-A.—Western part of the village of Natashquan. B.—.Aspect of the shore near Kegashka. VII-A. — Mistassini harbour. B.—View near Cap Rouge point. VIII-A.--Inland topography as seen from near Musouaro. B.—Tidal flat. IX-A.—Aspect of the shore two miles east of Musquaro. B. — 'Sheeting' of granite, cairn, and triangulation station at Chicoutai point. X-A.—Entrance to Musquanousse river. B.—Entrance to Washicoutai bay. XI-A.— Paragneiss injected by pegmatite and quartz nodules. B.—Quartzite. XII-A.— Paragneiss granitized lit-par-lit. B.—Crumpled granitized paragneiss. XIII-A.— Thinly interbedded calcareous and quartzitic sedimentary rocks. B.—Crystalline limestone relict beds. XIV-A.—Crystalline limestone relict beds. B.—Banded gneiss. XV-A.—Banded gneiss. B.--Banded gneiss in contact with granite. XVI-A.—Granitic gneiss injected by thin ribbons of pegmatite. B.--Segmented dyke of 'black rock' in gneissic granite. XVII-A.—Splashy pattern of injection of pegmatite in a dyke of 'black rock'. B.—Nodular structure in dyke of 'black rock' cutting 'microperthite' granite. -II- XVIII-A. —Gneissic granite displaying 'augen' facies. B.--Pegmatite ribbons injected along foliation of gneissic granite. XIX-A.— Ptygmatic folding of a pegmatite ribbon in gneissic granite. B.—Cross-joints in granite. XX-A. --Cross-joints in granite. B. and C.—Feather-joints in gneissic granite. XXI-A. —Joint planes in granite tending to develop parallel to the foliation. B.— Rectangular jointing in 'microperthite' granite. XXII-A. —Rock surface well polished and grooved by the ice. B. — 'Crescentic gouges', a type of ice-marking on the rocks. XVIII --Photomicrographs. A.—Coronas around olivine crystals in olivine gabbro.X 30. B.— Anthophyllite schist. 0)(30. XXIV --Photomicrographs. -A.—Fluorite in 'microperthite' granite. X80. B.— Microperthite in granite of the same name. )(80. NORTH SHORE OF THE ST-LANBENCE AGUANISH TO PASHICOUTAI BAY SAGUENAY COUNTY By Jacques Claveau INTRODUCTION Location of Area This report describes the section of the north shore of the gulf of St-Lawrence between the village of Aguanish and Washicoutai bay, which was examined and mapped by the writer during the summer of 1944. Aguanish and Washicoutai bay are both at or near latitute 50°13'N. In a straight line they are some 55 miles apart, Aguanish at longitude 62°05'W. and Washicoutai bay at 60°53'W. Aguanish is about 515 miles below Quebec city and 90 miles nearly due east of Mingan village. Means of Access The only regular means of access to the area is the boat service maintained during the navigation season by the Clarke Steam- ship Company, Ltd. The boats have a fairly regular schedule during late spring and summer, but after mid-September the service becomes increasingly uncertain and it is discontinued in late fall or early winter, depending on the severity of the season. Chartered seaplanes or flying boats could be used, as many deep bays and island-sheltered waters offer excellent landing sites under normal weather conditions. Throughout the winter, a mail and passenger service to centres along the coast is maintained by Canadian Pacific Airlines. Previous Work The present investigation marks the first detailed geologic- al survey of the coast between Aguanish and Washicoutai bay and is an eastward continuation of the detailed investigation of the Precambrian - 2 - rocks of the coast between Mingan and Aguanish carried out by Longleyl in 1943. Richanison2, prior to 1863, visited the area and on the general map accompanying "Geology of Canada", published in 1863, the rocks along this part of the coast are classed under the very general terms "Laurentian granite and granite gneiss". De Puyjalon, in 18989 and 19004, described the area as under- lain by an assemblage of granitic gneisses, mica schists, and trap and basalt dykes. In the course of a rapid reconnaissance made in the fall of 1943 between Aguanish and Lobster bay, Longley5 noted a few scattered, small areas of schist and quartzite between Aguanish and Natashquan. Extensive deposits of magnetic iron sands that occur at the mouth of Natashquan river and that were mentioned in the literature as early as 18696 have been investigated from time to time. A partic- ularly thorough study, to which further reference will be made under the heading of Economic Geology, was carried out during the years 1911, 1912, and 1913 by the Mines Branch of the Federal Department of Mines. Field Work The maps used in the course of the work were the marine charts of the Canadian Hydrographic Service and the official survey maps of the coast and rivers,compiled by the Quebec Department of Lands and Forests. i Longley, W.W., North Shore of the St-Lawrence, Mingan to Aguanish, Saguenay County; Que. Dept. Mines, G.R. 42, Pt. I, 1950. 2Logan, (Sir) W.E., Geology of Canada, A Report of Progress Since its Commencement, p. IV and accomp. map; G.S.C., 1863. 3De Puyjalon, Henri, Monograph of the Minerals of the North Shore of the Gulf of St-Lawrence; Report of the Commissioner of Coloniz- ation and Mines of Quebec for 1898, pp. 269-270, 1899. 413e Puyjalon, Henri, Annex to the Report of the Inspector-General of Fisheries; Report of the Commissioner of Lands, Forests, and Fisheries of Quebec for 1900, pp.86-87, 1900. 6Longley, W.f., Aguanish to Lobster Bay, North Shore of the Gulf of St-Lawrence; Que. Dept. Mines, Special Report (unpublished), p.9, 1944. 6Hunt, T. Sterry, Report of Progress from 1866-1869, pp.265-267; G.S.C., 1870. - 3 - The marine charts were found indispensable for navigation and their excellence cannot be too highly praised. They are mercator projections on a scale of 1/69950, or one inch to 1.104 miles,. at latitude 50°05'N. The maps of the Department of Lands and Forests are polyconic projections on a scale of two inches to one mile. In the initial field work, traverses were made along the shore, using the pace-and-compass method of surveying. This method was soon abandoned, however, when it was found that, owing to the excellence of the available maps, one's position in the field could be very quickly ascertained by inspection of the map. A small draw- ing board, fifteen inches by eighteen inches, on which was tacked a tracing or sketch of the portion of the coast being surveyed, was carried along in the field. Rock outcrops were marked on the tracing or sketch as the observer walked along, and points at which special observations were felt necessary were marked by numbers corresponding to those used in the note-book in which the pertinent data were re- corded. Only very seldom was the shoreline so regular that easily recognizable landmarks were lacking. In cases of doubt as to position, the pace-counter and compass were used to re-trace the distance to a known point or to keep record until a conspicuous landmark was reach- ed. The use of aerial photographs, which were secured late in the season, permitted elimination of the pace-and-compass method and also of the tracings mounted on a board. The photographs were carried dur- ing the field work and, at each point of observation, a pin-hole was driven through the photograph. Numbers, written on the back of the prints adjacent to the pin-holes, served the same purpose as those used on the sketches. Four successive base camps were established across the area as the work progressed. A 40-foot motor-driven fishing-boat, owned by Walter Cormier of Havre St-Pierre, was permanently at the disposal of the party and was used for all necessary travelling. It was, how- ever, not well suited for the type of work for which it was required. A boat — which need not be much larger — fitted with living and working quarters for all members of the party would be more satisfac- tory. This would eliminate the necessity for shore camps, which are often very difficult to locate as the site must meet several require- ments.