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The map-area lies in the mining camp in the District of Algoma about half-way between Sudbury and S-ault Ste. Marie^ The town of Elliot Lake^ serving the uranium mines of the district, lies in the southern part of Township 149 immediately t o the south. Access t o Elliot Lake from Hwy. 17 i s by Hwy. 108. A northwestwards extension of Hwy. 108 t o meet Hwy, 546 i s under construction^

The area was included in Collins' (1925) report on The North Shore of Lake Huron^ Detailed mapping (1 inch t o 4^ mile) was carried out by Abraham (1956) and revised by Robertson in 1962 and I963. Adjacent areas have been mapped by Ontario Dept^ Mines (McDowell 1957i ONTARIO DEPARTMENT OF MINES Robertson, I960, 1961, 1962, 1963a, 1963b). Roscoe (1957, 1958) and Pienaar (1958) of the Geol. Surv, Canada have carried out considerable PRELIMINARY GEOLOGICAL MAP No. P. 192 work in the district. Much geological and mining information has been published by the mining companies of the area(C.I M.M,), TOWNSHIP ISO General Geology DISTRICT O F ALGOMA

The regional geology i s shown on O.D.Mo map No., 2032. The rocks belong t o three main units; (1) the Algoman-Keewatin basanent, (2) the Scale I Inch t© 1/4 Mile Huronlan sedimentary rocks and (3) Keweenawan basic intrusions (Nipissing type). Pleistocene and Recent sands, gravels, and swamp deposits cover the bedrock in places. N.TS. Reference 41 J/7, 41 J/IO The oldest Precambrian rocks exposed are Keewatin (?) volcanic O.D.M. Aeromagnefic Map 42 rocks with minor pyroclastics and metasedimentary rocks. These are exposed t o the northeast of Quirke Lake but are known t o underlie the Huronian in the southeast part of the township.

The Keewatin (?) rocks are intruded by the Algoman granites* The latter may be divided into two groups. The first consists of grey t o pink, massive t o gneissic, granodiorite t o granite with numerous Keewatin (?) inclusions. The second i s a massive t o porphyritic quartz monzonite, generally without inclusions and slightly radioactive. The northern third of the township i s largely underlain by the second typej in the southwestern part of the township, the Huronian i s probably underlain by granites of the first type.

After the intrusion of the granitic rocks the region was eroded t o 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, Uraniferous quartz-pebble conglomerate of the Lower Mississagi Formation was deposited in local channels and depressions. Major uranium deposits were formed in the Quirke channel of the Elliot Lake troughj the location of this depression was controlled by the underlying granite-greenstone contact. Conglomerates, quartzites, siltstones, and limestones, all derived from the northwest and deposited in cold shallow water, make up the various formations of the Bruce Group* The lower formations of the Bruce Group overlap northwards along the shore of Quirke Lake. The upper formations of the Bruce Group are well exposed on the west shore of Quirke Lake# In the southwest part of the township they may be cut out by an unconformity. The Bruce Group i s overlain unconformably by the Cobalt Group which, in Township 150, consists of the Gowganda Formation and the Lorrain Formation. The Gowganda Formation i s a heterogeneous assemblage of conglomerates, quartzites, greywackes, and siltstones} the lower part may have formed under glacial or subglacial conditions. There are excellent exposures along Hwy. 108., Crossbedded feldspathic quartzites correlated with the Lorrain Formation are exposed t o the south of Dunlop Lake.

The above mentioned rocks were folded about a synclinal axis trending slightly south of east and lying just south of Dunlop and Quirke Lakes, Large irregular sill-like diabase bodies were intruded into ^tensional' areas of the fold, Some faults and joints were developed parallel t o the bedding and t o the axial plane of the fold; others strike north, northwest, and northeast. 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 the past this diabase has generally been correlated in age with the Keweenawan diabase but i t i s of the Nipissing type; recent age determinations show that i t i s much older than the Keweenawan period. Local albitization, chloritization, 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 valley of the Serpent River^ Several large pits were opened during the construction of Elliot Lake and development of the surrounding area•

Economic Geology

Extensive prospecting has been carried out, mainly for uranium, in the period 1953-1-957* Much of the central and southern parts of the township was drilledo A zone containing uraniferous quartz-pebble conglomerates of ore grade was delineated at or near the base of the Lower Mississagi Formation in the Qu^lirke Lake area and eastward into Township 144 (Robertson, 196I),

The zone strikes northwest-southeast and i s apparently controlled by basement structure and i s also parallel t o the current-direction as shown by structures preserved in the rock (McDowell, 1957). The total length of the ore zone in the direction of the channel i s 32,000 feet and the lateral extent varies from 6,000 t o 9,000 (Derry, I960).

The conglomerates consist of well-rounded, well-sorted, quartz pebbles in a matrix of quartz, feldspar, and sericite and a pyrite content of 15-25 percent, Monazite and zircon are characteristic heavy minerals, Brannerite and uraninite are found as submicroscopic grains in the matrix^ Thucholite i s found locally. Individual conglomerate bands a few feet in width may assay as high as 20 lbs, or more, U30g t o the ton, but over mining widths of the order of 9 feet t o 30 feet the average grade i s 2-3 lbs. U30g per ton. I t i s generally believed that the deposits are of placer origin but that some modification and redistribution of the uranium minerals took place after deposition.

Production was begun at the Quirkemine in September 1955, at the in March 1957 and the Spanish American mine in March 1958. The Spanish American mine closed in February 1959* Following reorganization of companies in the Rio Tinto group t o form Mines Limited, the was placed on a care and maintainance basis (in January 1961), The Denison mine i s expected t o complete contracted production by May I964, but will benefit under a Federal Government undertaking t o stockpile uranium production until July 1964* The .part of the Stanrock orebody in Township I50 has been mined out. Total uranium (U^Og) production and value of production for companies operating in the Blind River ­ Elliot Lake district t o the end of 1962 i s given below. Tons Value $ 1955-1960 2,264,404 1955-1959 44,649,075 Algom Quirke mine* 1956-1961 4,173,327 1956-1959 70,404,220 Algom 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. 1960-1962 232,110,000 (Merger of above) 1958-1960 2,495,725 1958-1960 52,862,976 Stanrock mine (Twp.150-144) 1958-1962 4,819,537 1958-1962 91,021,869 Can Met mine 1957-1960 1,996,856 1957-1960 37,590,792 Denison mine* 1957-1962 10,397,282 1957-1962 206,287,387

Total Production Tonnage 44,937,871 Value 944,373,250 Elliot Lake ­ Blind River Approximate total Twpv 150 16,534,820

*Mine located i n Township I50.

Slightly more than I/3 of the district's uranium production has come from Twp« 150. In 1962, the Denison mine was the only mine i n production in the township; i t produced 1,828,993 tons valued at $39,791,162.

Selected Bibliography

Abraham, B^M, 1956: Preliminary map of Townships 149 and I5O; Ontario Dept. Mines, map No, P. 1 .

C.I.MM. 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, W.H. 1925: The north shore of Lake Huron; Geol. Surv. Canada, Mem„ 143.

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

McDowell, JcP^ 1957: The sedimentary petrology of the Mississagi quartzite in the Blind River area; Ontario Dept. Mines, Geol. Circ. No. 6,

Pienaar, P. J.^ 1958: Stratigraphy, petrography, and genesis of the Elliot Group including the uraniferous conglomerates, Quirke Lake syncline. Blind River area, Ontario; (unpublished Ph. D. thesis, Queen's University).

Robertson, J.A. 1960t General geology of parts of the Blind River area; (unpublished M.Sc thesis, Queen's University). I96I: Geology of Townships 143 and I44j Ontario Dept. Mines, Geol^ Rept. No, 4* 1962; Geology of Townships 137 and I38; Ontario Dept„ Mines, Geol. Rept, Noo 10, 1963a: Geology of Townships 155, 156, I6I, 162, (including Blind River ­ Elliot Lake area, map 2032); Ontario Dept. Mines, Geol. Rept, No, 13v 1963b: Preliminary map of Township 149; Ontario Dept. Mines map No. P. 193-

Roscoe, S.Mi, 19571 Geology and uranium deposits, Quirke Lake ­ Elliot Lake, Blind River area, Ontario; Geol, Surv. Canada, Prelim^ Rept,, Paper 56-7.

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