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The map-area lies in the mining camp (District of Algoma) about half-way between Sudbury and Sault Ste, Marie and about 20 miles north of the Trans Canada Highway (Prov, Hwy, No. 17)« The town of Elliot Lake^ serving the uranium mines of the district, lies in the southern part of the township. Access to Elliot Lake from Hwy. 17 is via Hwy. 108,

The area was included In Collins (19^5) report on the North ^ Shore of Lake Huron. Mapping (1 inch to 4 mile) was carried out by Abraham (I956), and was completed by Robertson in I963. Adjacent areas have been mapped by Ont, Dept^ Mines (McDowell 1957: Robertson, i960, 1961, 1962, 1963a, 1963b). Roscoe (1957, 1958) and Pienaar ONTARIO DEPARTMENT OF MINES (1958) of the Geological Survey of Canada have also carried out considerable work in the area. Much information has been published PRELIMINARY GEOLOGICAL MAP No. P. 193 by the staff of mining companies (C.I.M.M.), TOWNSHIP 149 General Geology

The regional geology is shown on 0„D^M, map 2032 (Robertson 1963a)c DISTRICT O F ALGOMA The exposed rocks belong to three main units; (1) the Algoman- Keewatin basement (2) the Huronian sedimentary rocks and (3) the Keeweenawan (Nlpissing-type) basic intrusions. Pleistocene and Scale I Inch to 1/4 Mile Recent sands, gravels, and swamp deposits locally cover the bedrock. N.T.S. Reference 41 J/7 The oldest Precambrian rocks exposed are Keewatin (?) volcanic rocks with minor pyroclastlcs and metasedimentary rocks including O.D.M. Aeromognetic Map 45 quartzite, greywackci and lean iron formation. These outcrop in the southeast corner of the map-area but are known to underlie the Huronian throughout the northeast half of the township.

The Keewatin (?) rocks are intruded by and included in the Algoman granites. The latter are grey to pink, massive to gneissic granodiorite to granite. These underlie the Huronian in the southwest ^ half of the township. A grey to pink porphyritic granodiorite lies south of Elliot Lake.

After the intrusion of granitic rocks the region was eroded to a peneplane; remnants of the soils and weathered rocks of this period are locally preserved.

Huronian sedimentation began with coarse-grained sediments derived largely from weathered granite. Uranlferous quartz-pebble conglomerate of the Lower Mlssissagl Formation was deposited in local channels and depressions. Major uranium deposits formed in the Nordic channel of the Elliot Lake trough; the location of this depression was apparently controlled by the underlying granite-greenstone contact^ ^ Conglomerates, quartzltes, slltstones, and limestones, all derived from the northwest and deposited in cold shallow water, make up the various formations of the Bruce Group, The upper formations of the Bruce Group are normally cut out by an unconformity but are exposed near Crotch Lake, Cyclic sedimentation is evident. The Bruce Group is overlain unconformably by the Gowganda Formation of the Cobalt Group, It is a heterogeneous assemblage of conglomerates, quartzltes, greywackes, and slltstones; the lower part may have formed under glacial or subglacial conditions^ The Bruce and Cobalt groups are well-exposed in road cuts on Hwy, IO8.

The above-mentioned rocks were folded about a synclinal axis trending slightly south of east and lying just north of the Townships ^ I49-I5O, boundary. Large irregular sill-like diabase bodies were intruded into ^tenslonal' areas of the fold. Some faults and joints were developed parallel to the bedding and parallel to the axial plane of the fold. Others strike north, northwest, or northeasts Data available on structure Indicate that the fold formed as the result of a north—south compression. During relaxation of the compressive forces fractures were intruded by quartz diabase. In previous reports this diabase has been generally correlated In age with the Keweenawan diabase but it Is of the Nipissing type; recent age determinations show that it is much older than the Keweenawan period. Local 'albitlzation, chloritlzatlon, and minor sulphide mineralization may be associated with the diabase Intrusions.

Pleistocene glaciation removed the soil and resulted in the deposition of sand and gravel, particularly in the south central part of the area. Several large pits were opened during the construction of Elliot Lake and development of the surrounding area.

Economic Geology

Extensive prospecting was carried out, mainly for uranium, in the period 1953-1957; a great deal of drilling was done in the - township, A zone containing uranlferous quartz-pebble conglomerates of ore grade was delineated near the base of the Lower Mississagi Formation to the east of Elliot^Lake, The zone strikes northwest- L southeast and is apparently controlled by basement structure and is / also parallel to the current direction as shown by structures preserved in the rock (McDowell, 19 57). The total length of the ore zone in the direction of the channel is 19,000 feet and the lateral extent varies from 4,400 feet to 6,000 feet (Derry, I960),

^The conglomeratefa consist of well-rounded, well-sorted quartz pebbles in a matrix of quartz, feldspar, and sericlte, and have a pyrite content of 15-25 percent, Monazlte and zircon are characteristic , heavy minerals^ Brannerlte and uraninlte are found as submicroscopic ^ grains in the matrix. Thuchollte is found locally. Individual conglomerate bands a few feet in width may assay as high as 20 lbs, or more, U30g to the ton but over mining widths of the order of 9 feet to 30 feet the average grade Is 2-3 lbs. U^Og per ton. It is generally believed that the deposits are of placer origin but that some modification and redistribution of the uranium minerals took place after deposition.

Mineral Production

Uranium production was begun at the in 1956; the Buckles, Stanleigh, Lacnor, and Mllllken mines were in production by early 1958ii The Buckles orebody was mined out by October 1958^ The was taken over by Preston Mines Ltd. and closed in I960, The Lacnor mine was closed in I96O following the formation of Mines Ltd. The Milllken and Nordic mines owned by Rio Algom Mines Ltd, were in production in 1963o The production from the Mllllken mine until July 1964 is being stockpiled. The Nordic mine is expected to remain in production until 1971i.

Total uranium (U30g) production and value of production for companies operating in the Blind River - Elliot Lake district to the end of 1962 is given below. Tons Value $ 1955-1960 2,264,404 1955-1959 44^649,075 Algom I956-I96I 4,173,327 1956-1959 70,404,220 Algom Nordic mine* 1957-1962 6,358,280 1957-1959 75,009,554 Northspan Uranium Mines Ltd,1957-1958 2,579,578 1957-1958 46,944,994 / Spanish American mine 1959 42,341 1959 767,922 { ' 1959-1961 2,851,244 1959 26,538,609 ^'^^ Lacnor mine* 1959-1960 2,026,350 1959 28,659,982 Milliken Lake mine 1958-1962 4,932,947 1958-1959 33,515,870 Rio Algom Mines Ltd, I96O-I962 232,110,000 (merger of above) Stanleigh mine* 1958-1960 2,495,725 1958-1960 52,862,976 Stanrock mine 1958-1962 4,819,537 1958-1962 91,021,869 Can Met mine 1957-1960 1,996,856 1957-1960 37,590,792 1957-1962 10,397,282 1957-1962 206,287,387 TOTAL 44,937,871 944,373,387 *Mine located in Twp. 149 The total production from Township 149 to the end of 1962 was 17,3 million tons; this is slightly less than 2/5 of the total production of the camp. In 1962 the Nordic mine produced 1,113,400 tons and the produced 958,390 tons for a revenue to Rio Algom Mines Ltd. of $46,096,000.

Selected Bibliography ^

Abraham, £^M^ 1956: Preliminary map of Townships 149 and 150; Ontario Dept^ Mines, map No, P, 1 .

C.I.M.M. 1957' Mining, metallurgy and geology in the Algoma uranium area; (published for the Sixth Commonwealth Mining and Metallurgical Congress, 1957); Canadian Inst, Min. Met,

Collins, WoH. 1925: The North Shore of Lake Huron; Geol^ Surv. Canada, Mem^ 143..

Derry, D.R. I96O: Evidence of the origin of the Blind River uranium deposits; .Economic Geol,, Vol. 55, pp. 906-927-

McDowell, J.P. 1957: The sedimentary petrology of the Mississagi quartzite in the Blind River area; Ontario Dept. Mines, Geol, Clrc. No, 6.

Pienaar, PcJo -I958: Stratigraphy, petrography, and genesis of the Elliot Group Including the uranlferous conglomerates, Quirke Lake syncllne. Blind River area, Ontario; (unpublished Ph. Dc thesis, Queen*s University), Robertson, J^A. I96O: General geology of parts of the Blind River area; (unpublished M^ S<- thesis, Queen's University) . I96I: Geology of Tc^nshlps I43 and 144; Ontario Dept. Mines Geolc Rept. No. 4• 1962: Geology of Townships 137 and I38; Ontario Dept., Mines Geolv Rept. No. 10, 1963a: Geology of Townships 155, 156, I6I, 162, (including Blind River - Elliot Lake Area, Map 2032); Ontario Dept^ Mines, Geol^i Rept. No. 13* 1963b: Preliminary map of Township I50, Ontario Dept, Mines, map No. P. 192.

Roscoe, S.M, 1957: Geology and uranium deposits, Quirke Lake-Elliot Lake, Blind River area, Ontario; Geol, Surv. Canada, Prelim, Reptc, Paper 56-7-

Roacoe, S^M., and Steacy, H,R. 1958: On the geology and radioactive deposits of Blind River region; Atomic Energy of Canada Ltd., A. Conf., 15/P/222fc