Highlights of Quaternary Geology Investigations in the Sturgeon-weir River Area near Flin Flon 1

I. McMartin 2 and J.E. Campbell 3

McMartin, I. and Campbell, J.E. (1994): Highlights of Quaternary geology investigations in the Sturgeon-weir River area near Flin Flon; in Summary of Investigations 1994, Saskatchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 94-4.

Quaternary geology investigations in the Sturgeon-weir River area, Saskatchewan, were initiated in 1992 under the NATMAP Shield Margin Project with the objectives of: mapping the surficial deposits at 1: 100 000 scale, studying the glacial history, and conducting a regional till sampling survey. Preliminary maps based on air­photo interpretation were completed in early 1992. Dur­ing the 1992 and 1993 summers, field work was carried out along the road network and on road-accessible lakes. During this past summer, field work was centred in two areas: 1) on the Paleozoic cover with air support, for regional till sampling and surficial mapping (63K-4 and -5; 63L-1,- 2, -7, -8, and -10), and 2) in the Mirond Lake area (63M·2). for detailed work along lake shore­lines. This report summarizes the Quaternary geological investigations carried out to date in the study area.

1 . Regional Setting

The Sturgeon-weir River area near Flin Flan straddles the Paleozoic-Precambrian boundary near the Manitoba­Saskatchewan border (Figure 1 ). The Precambrian Shield portion is underlain by parts of the Flin Flan and Kisseynew domains and the Hanson Lake Block of the Trans-Hudson Orogen (Macdonald, 1987). The Phanerozoic cover includes subhorizontal Paleozoic dolomitic rocks and minor sandstones at the base of the sequence (Kupsch, 1952).

The predominant ice flow direction across the study area is to the south-southwest, indicating that glacier ice was flowing from the Keewatin Sector of the Lauren­tide Ice Sheet (Figure 1 ). Following ice retreat, the en­tire study area was inundated by glacial Lake Agassiz. Most of the Saskatchewan River delta was built as Lake Agassiz drained from the area. Several reports comment on the history of deglaciation and the nature of surficial sediments in northern Saskatchewan. The most comprehensive studies include those by Elson (1967), Langford (1977), Teller and Clayton (1983), and Schreiner (1984).

The till cover on the Shield is generally thin (<3 m) and discontinuous, and is commonly found on the down-ice side of bedrock hills. Ice contact ablational and glacioflu­vial sediments are also prevalent, namely around Peli­can Narrows and Attitti Lake and along the

(1) Contribution to the NATMAP Shield Margin Project.

Sturgeon-weir River, where they form an extensive but rather thin cover. Over the Paleozoic rocks, the drift cover is more continuous and, in the most western part of the study area, commonly moulded into long drum­lins. Fine grained glaciolacustrine sediments form a dis­continuous veneer on the irregular topography, with thickest accumulations in the low areas between bed­rock highs on the Shield, or in low lying areas across the Paleozoic terrane.

Q Mesozoic sedimentary rock

j ·.· ·, '': ·J Paleozoic carbonate rock

PRECAMBRIAN

-

Greenstone belt & associated intrusions

LJ Granitic intrusions, gneiss & mlgmatite

NA TMAP SHIELD MARGIN AREA

STUDY AREA

/ Ice flow direction - Major moraine

150km

Figure 1 - Location map of study area within the NATMAP Shield Margin Project area showing regional ice flow trends and major moraines (taken, in part, from Klassen, 1983).

(2) Terrain Sciences Division, Geological Survey of Canada, 601 Booth St., Ottawa, Ontario, K1A OES. (3) Saskatchewan Research Council, 15 Innovation Blvd., Saskatoon, Saskatchewan, S7N 2X8.

Saskatchewan Geological Survey 137

2. Ice Flow Record

On the Shield, the bedrock is commonly striated, pol­ished, grooved or carved into roches moutonnees, with a predominant orientation of 196° (186° to 214°)(Figure 2). Local variations of this main ice flow are found around steep outcrops, along lakeshores, and in narrow valleys, which provide evidence of the strong influence the underlying topography had on this late glacial move­ment. On the Paleozoic cover, the dominant ice flow has three different components trending to the south­southwest (Figure 2): 1) in the west, drumlins parallel the main ice flow coming off the Shield, and trend 186° to 198° (Figure 3); 2) south of Amisk Lake, striae direc­tions curve towards the west, from 204° to 225°; and 3) in the Namew Lake area, striae deviate toward the south, from 211 ° to 192°. These variations in ice-flow trends across the flat plains are related to complex ice flow events that occurred in the adjacent areas, namely to the north in the Amisk Lake area (Henderson and Campbell, 1992), and to the east in the Cormorant Lake area (McMartin, 1994). These events resulted from the confluence of two major Late Wisconsinan ice lobes, the Hudson and Keewatin lobes, along the Shield boundary in the NATMAP Shield Margin Project area (McMartin, 1994).

A southeasterly ice movement (130° to 162°), which pre­dates the dominant flow, was recorded at a few sites on the Shield. This event can be related to an earlier flow found sporadically across the Cormorant Lake area (McMartin, 1994) and throughout north-central Manitoba (Nielsen and Groom, 1987). Rare, southwesterly ori­ented striae were also noted on the Shield (220° to 232°), some predating, and others postdating the domi­nant south-southwest ice flow. On the Paleozoic cover, an early westerly flow of Hudson Lobe ice is recorded as far west as Namew Lake (McMartin, 1994), possibly defining the western extension of this early movement. Late movements are also recorded south of Amisk Lake. One major movement which curves from 225° to 250° toward Cumberland Lake (Figure 4) is possibly re­lated to a major southwestward readvance documented west of The Pas Moraine (McMartin, 1994).

3. Drift Composition

At least two, and possibly three, till units, which are as­sociated with the last glacial expansion of the Lauren­tide Ice Sheet (Late Wisconsinan), have been identified in the Sturgeon-weir River area near Flin Flan. The tills in the study area have inherited most of their physical and lithological properties from erosion of two contrast­ing bedrock lithologies, "hard" Precambrian rocks and fine grained "soft" Paleozoic carbonates.

The lower and most pervasive unit consists of a locally derived till overlying striated bedrock recording the pre­dominant local ice flow direction towards the south­southwest or southwest. On the Shield, the till is sandy and non-calcareous, and has a variable clast composi­tion, closely related to bedrock lithologies found immedi­ately up-ice from sample sites. This unit forms a very discontinuous cover, with thickest accumulations on the

138

lee-side of bedrock knobs, where glacial sediments were deposited in temporary cavities under the ice (Hillefors, 1975). This unit has been detected in expo­sures and auger holes in the region by Schreiner ( 1984), and in the Amisk Lake area by Campbell (1988) and Henderson and Campbell (1992).

South of the Shield margin, this lower unit grades into a silty-sandy calcareous till, as the Shield load is quickly diluted by large quantities of Paleozoic debris. Regional variations in the colour, and possibly the carbonate con­tent of the till, are closely related to the underlying Pa­leozoic Formations. In fact, in the Namew Lake and Cumberland Lake areas, the till matrix abruptly be­comes yellowish-orange as it is carried onto the Stony

older

main

o 15 km

MDA area

Main Ice Movements

--~ younger

Figure 2 - Regional ice flow directions compiled from detailed mapping of ice flow indicators measured in the study area (102 sites). The Saskatchewan River delta and floodplain sediments appear in the southern part of the study area (dotted pattern). The Amisk Lake area near Flin Flon (MDA) is being studied by Henderson and Campbell (1992, this volume).

Summary of Investigations 1994

1991; Haidl, 1992). In the drumlins of the western part of the study area, the surface till is strongly cal­careous, silty-sandy, and com­monly grey to beige, reminiscent of the Red River Formation outcrop­ping up-ice from the drumlin field. In this area, the till composition ap­pears to be more distally derived.

A younger till was recognized at a dozen sites on the Paleozoic

Figure 3 • South-southwest-trending drumlins, in the middle background, occur in the Saskatchewan River floodplain. Aerial view is toward the southwest.

cover, overlying fine-grained glacio­lacustrine sediments or the lower till. This upper unit is clayey-sandy, weakly calcareous, and clast poor, reflecting the incorporation of the underlying glacial sediments which have been overridden. This unit was commonly found in the Cormo­rant Lake area, and is associated with a major readvance in Glacial

Figure 4 • Striated surface along the northern shore of Cumber­land Lake indicating ice flowing toward 250°. Note right end of compass needle points north.

Mountain Formation, and then reddish-orange on top of the Stonewall Formation. Both of these Lower Paleo­zoic formations are known to contain dolomitic and argil­laceous beds of brown to red (Kupsch, 1952; Bezys,

Saskatchewan Geological Survey

Lake Agassiz (Till #3, McMartin, 1994). In the study area, the extent of this unit on the Paleozoic terrane appears to be restricted east of the drumlin field, between Amisk Lake and Cumberland Lake, and possibly defines the western extension of the southwestward readvance.

On the Shield, an upper sandy-silty, non-calcareous diamicton exists at several sites, overlying the lower till, glaciolacustrine sediments, or capping an ice contact glaciofluvial sequence. This upper unit was also recog­nized in the surrounding areas by Schreiner (1984), Campbell (1988), and Henderson and Campbell (1992). Additional field work on the Shield will help to determine whether this diamicton represents the counterpart of the readvance till found south of Amisk Lake.

4. Drift Prospecting

A regional till sampling program was initiated in the study area as part of the NATMAP Shield Margin Pro­ject. A total of 162 till samples (3 to 4 samples per 100 km2) have been collected since 1992, mostly from hand-dug pits in the upper C horizon, and are analyzed for textural, petrological, and geochemical charac­teristics. Humus samples were also collected at the same sites for trace element analysis. The analytical methods are consistent with those used within the NAT· MAP Project (Nielsen, 1992, 1993; McMartin and Prin­gle, 1994; Henderson and McMartin, in press).

5. Acknowledgments

We are grateful to Robert Boucher, Marko Koprivnjak, Manfred Hebel, Barry Paquin, and Stephen Warner for their invaluable field assistance. Special thanks to Penny Henderson for discussions and comments, and to Tracy Barry for preparing the diagrams.

139

6. References Bezys, R.K. (1991): GS-14 stratigraphic mapping (NTS 63F,

63K) and core hole program 1991; in Manitoba Energy and Mines, Minerals Division, Report of Field Activities, 1991, p61 ·73.

Campbell_, J.E. (19~): Preliminary report-Quaternary geology and till geochemistry-East Amisk Lake area, Saskatche· wan; Sask. Resear. Counc., Rep. R-842-59-E-88.

Elson, J.A. (1967): Geology of Glacial Lake Agassiz; in Mayer­Oakes, W.J. (ed.), Life, Land and Water, Winnipeg, Univ. Manit. Press, p37-96.

Haidl, F.M. (1992): Correlation of outcrop and subsurface data from Lower Paleozoic strata, Cumberland Lake-Namew Lak~ ar~a. east-central Saskatchewan; in Summary of ln­vest1gat1ons 1992, Saskatchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 92-4, p213·219.

Henderson, P.J. and Campbell, J.E. (1992): Quaternary stud· ies in the Annabel Lake-Amisk Lake area (NTS areas 63L· 9 and -16 and part of 63K·12 and -13); in Summary of Investigations 1992, Saskatchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 92-4, p172·176.

Henderson, P.J. and McMartin, I. (in press): Mercury distribu· tion in humus and surficial sediments, Flin Aon, Manitoba, Canada; in Water, Air, Soil Pollution.

Hillefors, A. (1975): The stratigraphy and genesis of stoss- and lee~side moraines; Bull. Geol. lnstit. Univ. Uppsala, New Sanes vs, p139-154.

Klassen, R.W. (1983): Lake Agassiz and the late glacial history of northern Manitoba; in Teller, J.T. and Clayton, L. (eds.). Glacial Lake Agassiz, Gaol. Assoc. Can., Spec. Pap. 26, p97-115.

140

Kupsch, W.O. (1952): Ordovician and Silurian stratigraphy of east-central Saskatchewan; Sask. Dep. Miner. Resour., Rep. 10, 62p.

Langford, F.F. (1977) : Northern extent of Lake Agassiz in east­ern Saskatchewan; Can. J . Earth Sci., v14, p1286·1291 .

Macdonald, R. (1987): Update on the Precambrian geology and domainal classification of northern Saskatchewan; in Summary of Investigations 1987, Saskatchewan Geologi­cal Survey, Sask. Energy Mines, Misc. Rep. 87-4, p87-104.

McMartin, I. (1994): Ice flow events in the Cormorant Lake­Wekusko Lake area, Northern Manitoba; in Current Re· search, Pl. C, Geol. Surv. Can., Pap. 94-1C, p175-182.

McMartin, I. and Pringle, G. (1994): Regional kimberlite indica­tor mineral data and till geochemistry from the Wekusko Lake area, north-central Manitoba; Geol. Surv. Can., Open File Rep. 2844, 75p.

Nielsen, E. (1992) : Surficial geology mapping and glacial dis­persion studies as aids to geochemical exploration and mineral tracing in the Elbow Lake area (NTS 63K-15); in Manitoba Energy and Mines, Report of Activities, 1992, p52·55.

_ ___ (1993): Surficial geology and till geochemical sam­pling in the Naosap Lake area (NTS 63K·14); in Manitoba Energy and Mines. Report of Activities, 1993, p47·49.

Nielsen, E. and Groom, H.D. (1987): Glacial and late glacial history of The Pas area; in Schreiner, B.T. (ed.), The Qua­ternary between Hudson Bay and the Rocky Mountains, Xllth INQUA Congress, Ottawa, Excursion Guide C-13, Nat. Resear. Counc. Can., NRC 27533, 45p.

Schreiner, B.T. (1984): Quaternary geology of the Precambrian Shield, Saskatchewan; Sask. Energy Mines, Rep. 221 , 106p.

Teller, J.T. and Clayton, L. (eds.)(1983): Glacial Lake Agassiz; Geol. Assoc. Can., Spec. Pap. 26, 451p.

Summa,y of Investigations 1994