Project 1: La Ronge (East) and Hunter Bay (West) area Geological Survey of 73-P-2(W) and 73-P-3(E) by L. H. Forsythe

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1 - 3 - Project 1: La Ronge (East) and Hunter Bay (West) area Geological Survey of 73-P-2(W) and 73-P-3(E) by L. H. Forsythe The area is located on Lac La Ronge and bounded by latitudes 55 00'' to 55 15' north and longitudes ' to ' west. There is good access by Lac La Ronge to the islands and to parts of the Churchill River and Wapawekka Lake. Relief rarely exceeds 50 feet and many islands rise only 10 to 20 feet above the lake level. The Geo logical Survey of Canada has reported on t he area in Mcinnes (1910) and McLarty (1936). Saskatchewan Government wor k includes that of Mawdsley and Grout (1951) who geologically mapped the Stanley sheet northeast of the area here described and Padgham ( 1966, 1967) who surveyed the Wapawekka Lake Area to the southeast. For sythe, also for the Saskatchewan Geo l ogical Survey, has mapped to the north and west, the results of which are pr oduced i n several r eports produced since Map Units Mapping was carried out using the lithological units adopted i n t he Stanley (West) and Nemeiben Lake (East) areas (Forsythe, 1968, 1971). Exposed bedr ock in the area is mainly granitic, consist i ng of gr anite ( 16), gr anodiorite (15,16), quartz monzonite ( 16), and quartz-diorite (15) gneisses. Migmatised bands of hornblende gneiss (3), calc - silicate gneiss (4), amph i bolite (3) with associated meta-dior i te (14), metagabbro (14) and meta-pyroxenite (12) occur north of English Bay; between Nut Bay and Moysey Peninsula, on the islands south of Kidd Island to t he south of Bear Island; through Nelson, Pow and Grey-Noble, Cowan, Clark and Fox Islands, on Black Island, and around Adamson and Abrams Bays. There are many inclusions of similar rocks in the gr anitic terrain also, suggesting that the c omplex once was more extensive. Felsic to mafelsic biotite gneisses (7) also occur as migmatized i nclusions as well as i n a l ar ge zone of var iable width t o the northeast of Whitley Island between the Murphy, Brook and Freeman Islands, and similar r ocks occur i n the regi on of Abrams

2 - 4 - and Adamson Bays. Feldspathic quartzite (10) is abundant in the Howard Island to Quinlan Island area, Pegmatites (17) are widespread with large bodies (locally radioactive; trenched and drilled) occurring south of English Bay and in the Adamson-Abrams Bay country. Structure the area. Gneissose structures of various ages vary in prominence throughout Layers (designated So and Sl) in units 3, 4, 6, 7, and 10 and an (ortho?) gneissose structure (also possibly So and Sl) in units 14, 15 and 16 have been folded in later episodes into tight to isoclinal variabletrending structures of near upright to recumbent attitude. Poor- to welldeveloped axial plane foliation (Sl) commonly survives locally. A welldeveloped gneissose structure with a general northeasterly trend commonly masks old gneissose structure in the granitic gneisses and is probably axial planar to a prominent northeast fold trend. These northeasterly folds are commonly slightly deformed by northwest-trending'cross folds and locally by east and north-trending warps and rolls, but axial planar foliations do not appear to have been produced by these cross folds and warps. East of English Bay to the south of Bear Island there is overprinting by a northnorth-east fold trend and related axial planar foliation which is possibly the last folding episode in the area. This trend also occurs in the Abrams-Adamson Bays vicinity. The early folds are commonly associated with "b" lineation directions which produced boudins, rods, mineral streaks and mineral lineations. Later fold episodes have locally transposed these structures to various degrees, producing new "b" lineation elements. Shears of various trends were noted with dominant trends of azimuth , 035, 045, and 065. Trends of due north, 090 and 125 are locally prominent. Secondary foliations commonly occur paralleling these shears as also do other lineaments, some of which are faults. Padgham (1966, 1967) projected the Stanley fault south from Guncoat Bay, Churchill River to the west side of Nipekamew Bay, Lac La Ronge. By this projection the fault should pass east of Cowan and Fox Islands and west of Black and Wolf Islands, trending about 020 azimuth. The projected fault at Guncoat Bay

3 - 5 - is about 035. The aeromagnetic map 8190 G depicts a linear zone trending 020 which occurs between Nelson Island to just east of Black Island. The zone transects diverse northeasterly and east-north-easterly magnetic trends, which occur on both its flanks and it appears to die out in the vicinity of Guncoat Bay, although it is still seen to transect the 035 azimuth Stanley fault. Common shears of 020 and 035 were noted on Lac La Ronge so the Stanley fault may be transected by a later 020 azimuth fault zone. Economic Geology A uranium prospect south of English Bay was trenched and drilled by Westpol Explorations Limited in the mid-nineteen fifties. Radioactive zones over small areas occur in pegmatite and granite in a sporadic manner, mainly on and near Hot Point. Yellow bloom occurs in patches, commonly along joints, fractures, shears and near biotite aggregates. Uraninite, with possibly pitchblende is also reported. A nickel-copper prospect in mafic rock on Abrams Bay could not be evaluated because of poor weather and flooding of a trench by a rise in the Lac La Ronge water level. The country rock here is extensively rnigmatized and complexly folded. In some places throughout the area there are abundant mafic intrusives that commonly contain up to five per cent iron-sulphides. Pyrite and graphite occur in Unit 7 and 10 in a few localities. Geophysical investigations and diamond drilling have been undertaken this season in the northwest part of the area, north of English Bay by members of the La Ronge Horseshoe Mineral Evaluation project. References Forsythe, L.H. (1968): The Geology of the Stanley Area (West Half) (MacKay Lake Area); Sask. Dept. Min. Res. Rept. No.115, Part 1. (1971a): The Geology of the Nemeiben Lake Area (East Half) and the Geology of Mineral Deposits of the Stanley Area (West Half) and the Nemeiben Lake Area (East Half); Sask. Dept. Min. Res. Rept. No.115, Part 2.

4 - 6 - Forsythe, L H. (197lb): The G~ology of the Clam Lake Area (West Half); Sask. Dept. Min. Res. Rept. No (1972a): The Geology of the Clam Lake Area (East Half); Sask. Dept. Min. Res. Rept. No (1973): General Geology of the Lac La Ronge Region (73-P); in An Excursion Guide to the Geology of Saskatchewan, Sp. Pub. No.l, pp , F. Simpson Ed. (in press): The Geology of the Nemeiben Lake Area (West Half) and the La Range Area (West Half); Sask. Dept. Min. Res. Rept. No Mawdsley, J.B. and Grout, F.F. (1951): The Geology of the Stanley Sheet; Sask. Dept. Min. Res. Rept. No. 4. Mcinnes, W. (1910: Lac La Ronge District, Saskatchewan; Geol. Surv., Canada, Sum. Rept. 1909, p McLarty, D.M.E. (1936): Lac La Range Sheet West Half; Geol. Surv. Can. Map 357A with marginal notes. Padgham, W.A (1966): The Geology of the Guncoat Bay Area; Sask. Dept. Min. Res. Rept. No. 78. (1967): The Geology of the Wapawekka Lake Area (North Half); Sask. Dept. Min. Res. Rept. No Geol. Survey of Can., Geophysics Paper 8190, (1971): Aeromagnetic Map 8190G. Lac La Range, Sask;

Report of Activities 2003 Published by: Manitoba Industry, Economic Development and Mines Manitoba Geological Survey, 2003.

Report of Activities 2003 Published by: Manitoba Industry, Economic Development and Mines Manitoba Geological Survey, 2003. ERRATA: The publisher/department name in the bibliographic reference cited immediately