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MINISTERE DE L'ÉNERGIE ET DES RESSOURCES ,B DIRECTION GENERALE DE L'EXPLORATION GÉOLOGIQUE ET MINERALE
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PYTHONGA LAKE AREA
J.H. Bourne
1970 DP-151 GM-28638 OPEN FILE MANUSCRIPT
Gouvernement du Québec
DEPARTMENT OF NATURAL RESOURCES
GEOLOGICAL EXPLORATION SERVICE
GEOLOGY OF PYTHONGA LAKE AREA
Preliminary report
by
James Bourne
PUBLIC
Ministère des Richesses Naturelles, Québec SERVICE DE LA DOCUMENTATION TECHNIQUE 2 5 MAI 1973 Date: ~ Quebec No GM: 1970 INTRODUCTION
The Lac Pythonga area lies between 76°00W•and 76°30'W, and between 46°15'N and 46°30'N, and includes Artois and }3eliveau
Townships as well as parts of Boureogne, Perche, Isle-De-Prance,
Angoumois, Egan, Souchette, Church and Aunis Townships. Maniwaki
Township, most of which also lies within the area delimited above, is an Indian Reservation and was not mapped. Thus the mapping covered a surface area of some 345 square miles.
LOCATION AND ACCESS
The Town of Maniwaki (population 9,000) is located approximately
1 mile east of the eastern boundary of the area. The geographic centre of the area, Turtle Lake, is 16 miles from Maniwaki by road.
There are two main access roads into the area,-: one from the
Town of Gracefield, and the other from,Maniwaki. Both Maniwaki and
Gracefield are located on the paved Provincial Highway #11, and are
84 and 57 road miles north of Hull respectively.
There are numerous bush roads which have been built and are maintained by the Canadian International Paper Company (C.I.P.)
C.I.P. Route 1.1-: Runs between Eagle Depot and Maniwaki, following the Eagle River for some 15 miles.
C.I.P. Route 12-: Goes to the northwest corner of the area, passing by Turtle Lake and several others.
C.I.P. Route 35-: Runs from Eagle Depot up the west shore of Lac Pythonga, and out of the area to the northwest: C.T.P. Route 36-: Runs southwest from route 35 and effectively côvers the southwest corner of the area.
In the southeastern part of the area the main access road runs into the interior' from Messines or Parley. In the northeast part of the area a well graded provincial road, (known locally as the Montcerf Road) has been built from Maniwaki.
Numerous secondary roadslead into the larger lakes. The following important lakes are all accessible by road.
Depot Lake Harding Lake
Doyle Lake Kingsbury Lake
Lac Pythonga Turtle Lake
Lac David Green Lake
Inman Lake Lac Cairine
Lac Hel'ene Petit Lac-Aux-Cedres
Lac Jean Grand. Lac-Aux-Cedres
An excellent road map of this area is available through the C.I.P. office in Maniwaki.
Drainaçse& Physiography
With the exception of a very few streams, all streams drain into the Eagle River. Several streams develop drainage areas of considerable size before they themselves empty into the Eagle River. The western part of the area is in large part drained by the Hibou and Turtle Rivers.
Relief in the area is less than 400' locally, usually in the order of 150'.Hills are for the most part rounded and valleys filled with glacial debris. 3
Two broad physiographic provinces can be outlined, the Gatineau
Valley which is in. general a broad sand-filled plain underlain by
•marble, and'the highlands to the west of it which form the hilly
hinterland and out of which drain all the major streams.
Elevations vary from a low of 550' in the extreme eastern part
of the area along the Desert River to a high of 1592' in the north-
western corner of the area east of Lac David. The average elevation
rises from 800' in the east to 1100' in the west.
GEOLOGIC COLUI4N
Tectonic Unit Dominant Category Number Lithology
Syn and Post- 11 quartz veins Grenville Orogeny 10 lamprophyre intrusive rocks 9 diabase 8 diorite 7 granite 6 pegmatite 5 white rock Grenville Group 4 biotite - feldspar gneiss metasedimentary 3 marble rocks pre - Grenville 2 calc - silicate Group basement rocks if amphabolite 1 o le garnet (sillimanite) gneiss p.,ld biotite gneiss ôlc hornblende - biotite gneiss üilb granite gneiss la green rock complex
0 m GEOLOGY - INTRODUCTION
In the legend the writer has placed the rock units inte different "tectonic categories". In 'so doing he is following the practice established by Wynne-Edwards (1966, 1969) of mapping in this part of the Grenville Province. The proof that this concept is valid could best be arrived at by obtaining a number of Rb-Sr whole rock age determinations from each tectonic category which would then set out a rough time sequence of events. No such project has been attempted for this part of Quebec. However, in adjacent parts of Ontario such an investigation is being conducted, (Krogh et al (1968); Davis et al
(1967, 1969)) and has established a geochronologic framework for the Grenville Province of Ontario. Baer (1969), on the . basis of large scale mapping in both Ontario and this area of
Quebec under consideration felt that a correlation of the rocki across the river into adjacent western Quebec was possible, and divided up the rocks of western Quebec into three "blocks" each of which is envisaged to he of different primary age. The contact between his "Algonkin" and "Gatineau" blocks passes through the Lac Pythonga area and should, therefore, divide the rocks into groups of different age which, following the terminology of Wynne-Edwards, are, here
called "tectonic categories" and are listed below,
Tectonic Rock Types'Involved Category