Moose River Basin: geology and mineral potential - Geology Ontario

Moose River Basin
quite irregular in this area and appears to be controlled by structural highs in
the underlying Devonian bedrock. North of Onakawana, Mesozoic sediments
have been encountered in the subsurface near Portage Island, immediately
downstream from the confluence of the Missinaibi and Mattagami Rivers. A
small lignite field, known as the Portage field, has been defined at this location.
Many geological maps of the Moose River Basin (e.g.Sanford et al. 1968; Rogers
et al. 1975) show Cretaceous sediments extending as far north as the Kwata
boahegan River. However, at the present time, no definite surface or subsur
face occurrences of Mesozoic sediments have been recorded northwest of the
Onakawana and Portage Island area.
Sporadic drilling between Onakawana and Kipling Township, 60 km to the
southwest, suggests that the Mesozoic sedimentary cover is more or less contin
uous between these regions. An exception is the Grand Rapids area where pre
viously mentioned Paleozoic and Precambrian inliers are covered only by Pleis
tocene sediments.
Abundant outcrops of quartz sands and carbonaceous clays of the Matta
gami Formation occur along the Mattagami River and Adam Creek in Kipling
Township (Telford et al. 1975; Norris et al. 1976). Adam Creek is used as a div
ersion channel for Ontario Hydro dams on the nearby Mattagami River. Since
1966, when this diversion channel was created, severe and rapid erosion of the
stream banks has produced excellent exposures of Pleistocene, Cretaceous, and
Devonian strata (Photos 2.2 and 2.5). The total thickness of the Cretaceous sed
iments cannot be estimated from the surface exposures. However, Ontario Geo
logical Survey drillhole 75-05 (Figure 2.7), situated on Waboose River in Acres
Township, only about 15 km west of the Mattagami River, penetrated about a
53 m thickness of Cretaceous sediments.
Farther north in McCausland Township, Ontario Geological Survey drill
hole 75-06 (Figure 2.8) revealed a complete Cretaceous section of about 86 m
thickness. The Aquitaine-Sogepet Hambly No. l petroleum exploration hole in
Hambly Township found a similar thickness of Mesozoic (probably Cretaceous)
sediments. Between Hambly and McBrien Townships no surface or subsurface
occurrences of Mesozoic sediments are known, but it seems most probable that
Mesozoic deposits are continuous along this southern margin of the Moose
River Basin. Drilling in Garden and Wright Townships during the fall of 1978
by the Ontario Geological Survey has confirmed the presence of Mesozoic sedi
ments in this extreme southern part of the basin (Telford and Verma 1978).
As summarized by Price (1978), there have been numerous reports of Meso
zoic sediments in the vicinity of Missinaibi and Coal Rivers (McBrien and Bur
stall Townships), both in riverbank exposures and shallow drillholes. Many of
the outcrops described by early workers (Keele 1920; McLearn 1927) cannot be
examined at present as they have been obscured by erosion and slumpage of the
riverbanks. However there is little doubt that Mesozoic sediments are present
at relatively shallow depths throughout this area. Between 1965 and 1970, Algocen
Mines Limited carried out an extensive drilling and sampling pro
gramme in the northeast part of McBrien Township and located considerable
thicknesses of Mesozoic (probably Cretaceous) quartz sands and kaolinitic
clays (Vos 1975). Algocen found a maximum thickness of 51 m of the sands and
clays although this did not represent a total thickness of the Mesozoic unit as
Paleozoic bedrock was not reached by the drilling (Smith and Murthy 1970).
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