Abstracts of Dmr Reports
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- 222 - ABSTRACTS OF DMR REPORTS The following are abstracts of DMR reports by the Saskatchewan Geological Survey published or reprinted during the past year or scheduled to be released before 31 December, 1979: Beck, L.S. (1969; reprinted 1979): Uranium Deposits of the Athabasca Region; Sask., Dep. Min. Resour., Rep. 126, 139 p., 38 figs., 40 plates, 16 tables, 3 geol. maps. The Athabasca region is an important metallogenic largely pre-tectonic. In view of this, and because of the province of uranium and contains numerous epigenetic inherent structural differences between the two types of vein-type pitchblende deposits, some of which arc of geological environment, it is considered that the stable economic proportions, as well as many syngenetic occur blocks acted as relatively rigid units during the Hudsonian rences of uraninite in country rock and in pegmatite. This in contrast to the linear belts which were heavily faulted, report synthesizes existing geological information con mylonitized, and extensively granitized. Pitchblende cerning the region and presents the writer's own data bearing solutions were liberated during the final stages of collected over a four-year period as Resident Geologist at the Hudsonian granitization at about 1780 m.y. ago and Uranium City for the Saskatchewan Department of Mineral followed the crystallization of syngenetic uraninite in Resources and the results of subsequent work carried out at gneissic and granitic rocks transitionally. As the uranium the University of Leeds. The regional distribution, litho mineralization is related genetically to the Hudsonian logical and structural control, mineralogy, geochemistry, gra:iitization and mylonitization, the deposits are virtually and genesis of the uranium deposits are discussed and a restricted to the linear belts. The Hudsonian granites appear revised structural history of the region is proposed. The to be largely of metasomatic or replacement origin and thus known occurrences of uranium are listed and their locations it is likely that the various types of uraninite-bearing are shown on maps and the pitchblende deposits are occurrences represent stages of re-crystallization in the described individually. transformation (granitization) of country rock to granite and that a late stage in the granitization process was the The region forms part of the Churchill structural release of pitchblende-bearing solutions. province of the Canadian Shield and is underlain by a Precambrian sequence of regionally metamorphosed and Early pitchblende was deposited mainly from colloidal granitized rocks, the basement complex, which is charac sols, whereas later pitchblende, accompanied by a wide terized by a dominant northeast-trending 'grain' imparted variety of metallic accessory minerals, was probably trans by the Hudsonian orogeny (1750 - 1950 m.y. ago). In ported in aqueous solution as a hexavalent uranyl ion places, the peneplaned basement complex is overlain complexed under high pressures of C02 , and precipitated unconformably by flat-lying or gently folded, essentially by means of loss of pressure and catalytic reaction with elastic sequences, the so-called cover rocks. Basic dykes, ferrous iron. Maximum and minimum indicated temper intruded about 1400 - 1500 m.y. ago cut all rocks of the atures of deposition are 475° and 120°C,-although much of region. the JJitchblende was probably emplaced between 250° and On the basis of geological mapping and aeromagnetic 350 C. The open-space type of deposition in faults and interpretation of un-mapped areas, the basement complex is attendant structures together with textural features suggest divisible into two types of geological and structural that most of the deposits were fanned at relatively shallow environment: (1) the linear belts, consisting of a wide depths, probably less than 10,000 feet. variety of rock types including metasedimentary and metavolcanic rocks, paragneisses, basic intrusive rocks, and Since their formation, syngenetic systems (the uraninite granites, and characterized structurally by isoclinal folding, bearing deposits) have remained essentially 'closed' with intense faulting, brecciation, and mylonitization; and {2) low mobility of lead, but pitchblende deposits have been areas formed by similar amounts of granite, migmatite, and rejuvenated at several times by minor tectono-thermal paragneiss, the stable blocks, which are less heavily events including downwarping of the basement prior to faulted. Moreover, the bulk of the rocks of the linear belts deposition of the cover rocks, folding aria faulting of the are only weakly to moderately metamorphosed whereas cover rocks, intrusion of diabase, and late movements along many of the rocks in the stable blocks are in the granulite faults; the latest reworking may have taken place during the facies. In view of these significant differences the two last one hundred million years. environments are considered to represent different struc tural levels in the crust prior to the Hudsonian orogeny. Investigation of selected pitchblendes by X-ray powder diffraction methods show that they h-ave- a fairly uniform Whole-rock Rb-Sr measurements indicate two periods of particle size of about l(f5 cm which appears to be granite emplacement; one at 1820 ± 100 m.y. ago, independant of the degree of oxidation of the pitchblende. coincident with the Hudsonian tectonism, and the other at Cell-edge dimensions of two pitchblendes were determined 2200 ± 100 m.y. ago. The granitic rocks of the linear belts and gave values of 5.34A and 5.41A respectively. are mainly of the younger type whereas both types are Numerous Vickers Hardness detem1inations carried out on represented in the stable blocks. The relative proportion of pitchblendes from ten deposits, yielded reasonably con pre-tectonic and syn-tectonic granite in the stable block sistent values with test-loads of 200 gm or greater and range areas is not known although several large batholiths may be from 501 - 874 with a mean of 688. - 223 - Denner, M.J. (1978): Environmental Aspects of Oil and Gas Production in Saskatchewan; Sask., Dep. Miner. Resour., Mis. Rep. 78-5, ~·, 8 figs., 6 plates. The relationship of oil nnd natural gas to t11e en This report concentrates on that latter aspect. Its vironment is complex . main thrust is a portrayal of the activities of the petroleum industry in Saskatchewan within the Tl1e energy and petrochemical usages of these context of sound environmental safeguards. Other commodities are basic to the enjoyment of modern energy alternatives to oil and natural gas also have living standards and profoundly affect the quality of environmental impacts which are taken into ac life of every individual. Pollution control and count in the formulation of a total energy policy by ecological protection are another part of the the government. picture. The production of oi l and natural gas, with all the attendant social and economic benefits, need not cause extensive environmental damage. An important function of government 1s a super visory and regulatory role in attaining this goal. Denner, M.J. (1978): Mineral Resources of Saskatchewan; Sask., Dep. Miner. Resour., Misc. Rep. 78-11, ~. 8 figs., 11 tables. This booklet provides a general review of the principal mineral commodities of the province, namely: crude oil and natural gas, lignite, potash, sodium su]phate, uranium, base and precious meta]s and nickel. Commodities are described under the following h~adings: history, origin or geol ogy, produc tion and r eserves. Maps, graphs and tables illustrate various aspects of the provincial mineral industry. Denner, M.J. and Reeves, P.L. (1979): Mineral Resources of Saskatchewan; Sask., Dep. Miner. Resour., Misc. Rep. 79-11, ~' 8 figs., 11 tables. Denner, M.J. and Reeves, P.L., (1979): Uranium Reserves and Potential of Northern Saskatchewan; Sask., Dep. Miner. Resour., Misc. Rep.,~- 6 figs., 2 tables. Fuh, Tsu-Min (1979): Geology of the Gilbert Lake Area; Sask., Dep. Miner. Resour., Rep. 187. Precambrian rocks of the Gilbert Lake West area have been divided into three mappable units: biotite gneisses. hornblende gneisses and ultramafic rocks. Acid ic pegmatites, which may in part be a result.of metamorphic segregation or a product of granitization, pervade the area. Three directions of folding were distinguished. Northwest-trending isoclinal folds are found in the western and southern portions of the map area. northerly-trending asymmetric folds in the north-central to northeastern parts of the area, and large scale northeasterly-trending folds refolded the earlier folds. Mineral assemblages identified indicate that the rocks are in the amphibolite facies. Rocks in most of the southern half of the area have been partially melted or granitized. Minor amounts of disseminated pyrite and pyrrhotite occur in the hornblende gneisses and migmatitic rocks. - 224 - Fuh, Tsu-Min (1979): Geology of the Pagato River area; Sask., Dep. Miner. Resour., Rep. 207, ~' 3 tables, 10 plates, 1 geol. map. The Pr ecambrinn rocks recognized in the Pagato River Area comprise rnctnmorphosed sediments. diorite. granod1orite and pegmatite . The metasediments, which are of l<isseynew type , include biotite gneiss. garnet· cordierite biotite gneiss and hornblende plagioclase gneiss. At least three periods of deformation have affected the area. The first produced reg ional foliation in the metasediments, accompanied by low amphibolite facies metamorphism. Minor folds re lated to this deformation trend east-west.