ISERHOFF RIVER AREA, ABITIBI-COUNTY PROVINCE of QUEBEC, CANADA Department of Mines Honourable C

RG 049(A) ISERHOFF RIVER AREA, ABITIBI-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 49 ISERHOFF RIVER AREA ABITIBI-EAST COUNTY by Jacques Claveau QUEBEC RÉDEMPTI PARADIS PRINTER TO HIS MAJESTY THE KING 1951 Ministère des Richesses naturelles du Ou'bec @.JE SERVICE DOCUMENTATION TEC 4 .► IL. TABLE OF CONTENTS Page INTRODUCTION 1 Location and access 1 Field work - 2 Acknowledgments 3 Previous work 3 GENERAL DESCRIPTION OF THE AREA 4 Physiography 4 Topography 4 Drainage 5 Climate 8 Timber 8 Game 9 GENERAL GEOLOGY 10 Table of formations 10 General statement 10 Volcanic-sedimentary series 11 Volcanic rocks 12 Hornblende gneiss 15 Sedimentary rocks 16 Structural interpretation of the series in the southern belt 20 Basic intrusive rocks 23 General statement 23 Basic rocks in the volcanic-sedimentary series 24 Anorthosite-gabbro complex 26 Tamprophyre and porphyrite dykes 29 Acidic intrusive rocks 30 General statement 30 Quartz diorite 31 Quartz syenite 32 Quartz leueodiorite 33 Pink granite 34 Pleistocene and Recent 3~ STRUCTURAL GEOLOGY 36 Folding and faulting 36 Shearing 40 ECONOMIC GEOLOGY 42 Recommendations 43 BIBLIOGRAPHY 44 AIXBABETICAL INDEX 46 MAP AND ILLUSTRATIONS Map No.853.— Iserhoff River area (in pocket) Plates Plate I-A.— Two young Indians, Senneterre. B.- Indian winter house, Waswaniiii lake. Plate II Iserhoff river in the middle part of its course. Plate III Iserhoff river in the lower part of its course. Plate IV — Imbault creek. Plate V — Looking up the Iserhoff River valley. Plate - VI-A. — Panoramic view looking north from a vantage point east of Imbault lake. B.— View of Baptiste lake. Plate VII-A.— View of Dalhousie mountains. B.— View 'of a typical hill in the Dalhousie mountains. Plate VIII-A.— View along the top of a syenitic hill. B.— Layeredanorthosite-gabbro complex, Dalhousie mountains. -II-- ISERHOFF RIVER AREA ABITIBI EAST COUNTY by Jacques Claveau INTRODUCTION Iodation and Access The Iserhoff River area, mapped by the writer during the summer of 1946, is in Abitibi East county, some 80 miles north of Sen- neterre, a town on the Quebec-Cochrane branch of the Canadian National railway. It is bounded on the east and west by longitudes 76°45'.and 77°00' West, respectively, on the north by latitude 49°45' North, and on the south by the southern boundary of Berthiaume:and Bergères townships, that is, an east-west line about four miles south of latitude 49°30'. This gives an area of some 235 square miles, with a length of about twenty-one miles in a north-south direction and width of eleven miles. The north-south centre-line coincides with the boundary between the following pairs of townships, from south to north, the first named in each case being to the west: Berthiaume and Bergères, Bourbaux and Vignal, and Dussieux and Meulande. The area mapped thus includes a little more than half the width of each of these townships, and from south to north it extends the full length of the four first named and takes in the southernmost mile of Dussieux and Meulande. The most direct canoe route from Senneterre to the area is by way of Bell river, Wedding river, Duplessis stream, the lower part of O'Sullivan river, the southwestern bay of Waswanipi lake, and Iserhoff river. The last-named flows eastward across the southern part of the map-area and empties into Waswanipi lake at a point four miles east of the eastern border of the sheet. .An alternative, though somewhat longer, canoe route is by way of Bell river, Mattagami lake, Waswanipi river, and Olga lake to Goéland lake. This gives access to the northern part of the area, whereas the route first described leads to the southern part. Travel by air affords a much simpler and very easy means of access to the area. Hydroplane service is available from Senneterre, and all suitable landing surfaces in the area, such as Ramsay bay and Baptiste lake, and those within a short distance of the area,. such as Waswanipi lake, are. well within one hour's flying time from Senneterre. - 2 - Most points within the southern half of the map-area, except the district centred about Baptiste lake and the chain of small lakes to the north, can be reached by way of Iserhoff river and one of its main tributaries, Imbault creek. During the earlier part of the summer, when waters are still fairly high, Iserhoff river is easily navigable up to a point two miles and a quarter due east of the western boundary of the area. The river has about ten short rapids within this navigable stretch. Its tributary, Imbault creek, is a small, narrow stream (Plate IV), very difficult to navigate owing to heavy growths of alders which partially choke it. It is navigable, nevertheless, for a mile and a quarter above its confluence with the Iserhoff, whence a portage, three and a quarter miles long, leads to another short navigable stretch through which Imbault lake can be reached. Baptiste lake, near the western boundary of'the area, is accessible only on foot or by air — the latter means was used by the writer's party. Trails were cut to allow travelling, partly by land and partly by water, from Baptiste lake through the chain of four lakes lying to the north, which route gives access to that part of the northern half of.the area not within easy reach of Ramsay bay. Most other points in the remainder of the northern half of the area may be reached conveniently either from the southwestern part of extensive Goéland lake, in the northeastern corner of the map- area, or from Ramsay bay, a long, narrow arm extending for some six miles westward from the south end of the lake. Of the many streams that flow into Goéland lake, and principally into Ramsay bay, four are major streams, and two of these are navigable over a considerable distance. That flowing north into the deep, narrow, south-trending arm along the south shore of Ramsay bay is navigable for two and a half miles above its mouth, whence a trail, a mile and a quarter long, leads southeastward to the east-west surveyed line along latitude 49835'30". North of Ramsay bay, the large stream flowing eastward into Goéland • lake was ascended by motor-driven canoe as far as its first small rapid, five miles from its mouth. It was not explored above this point, but it is believed to be navigable by small canoe for some additional distance upstream. Of the other two major streams, the one that flows northward into the eastern end of Ramsay bay is navigable for one mile from its mouth, and the other, which empties.into the head of Ramsay bay, is navigable for a little more than half a mile. Field Work For purposes of mapping, the area was covered systematic- ally by pace-and-compass land traverses run at intervals of approximate- ly half a mile and across the trend of the general structure. - 3 - Acknowledgments The base-map used for plotting the geology was a copy on a scale of half a mile to one inch of a part of the original plans used in the compilation of the Waswanipi sheet (32F) of the National .Topographic Series of the Department of Mines and Resources, Ottawa. Oblique aerial photographs, taken by the Royal Canadian Air Force, were used in the field and were of some help. Vertical aerial photographs became available later, during the preparation of the report. The Department of Lands and Forests, Quebec, provided maps and plans of the surveyed lines and major lakes in the area. The writer was very ably assisted in the field by Paul- Emile Imbault of McGill University, Frank Bussell of the same university, and Paul Emile Grenier of Laval University. The two canoemen, Philippe and Aimé Lebrun, and the cook, Georges Vigneault, discharged their respective duties in a very satisfactory manner. The efficient and courteous service of Canu9ian Pacific Air Lines and, in particular, of Pilot W.J. Davis, in charge of the Senneterre base, and Pilot Wally Smith, is gratefully acknowledged. Previous Work The earliest recorded geological work in the region is that of Robert Bell (1, 2g who surveyed the basin of Nottaway river in 1895 and 1896. J.A. Bancroft (3), in 1912, mapped certain portions . of the basins of the Aarricana and Nottaway, including Goéland lake. More recent geological surveys that embrace the area itself include' those of Cooke (4), Lang (5) in 1931, Norman (7) in 1935, Freeman (11, 12), and'Sproule (9, 10) in 1936. Geological work in adjoining areas includes that of Mackenzie (6) in 1935 in the region to the south, Douglas (8) in 1935 in the region to the southwest, and Freeman and Black (14) in 1940 in the adjacent area to the west. XNumbers in parenthesis refer to corresponding numbers in the bibliography, page 44. - 4 - GENERAL DESCRIPTION OF TILE AREA Physiography Topography The southern two-thirds of the map-area, with the excep- tion of the lower reaches of Iserhoff river, lie in the northeastern central part of a well-defined topographical unit, characterized by its relatively high elevation and marked relief, and extending over some 650 square miles of Abitibi East county. This unit, elongated along a northwest-southeast axis, is bounded in the northwest by Olga lake, in the northeast by Goéland, 1aswanipi, and Puskitamika lakes, in the south by Wedding river, and in the southwest by a portion of Bell river.

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