IUREP ir.p.s. No. 161 January 1978 Distr. LIMITED Original: ENGLISH International Atomic Energy Agency INTERNATIONAL URANIUM RESOURCES EVALUATION PROJECT IUREP NATIONAL PAVOURABILITY STUDIES FALKLAND ISLANDS 78-1473 INTERNATIONAL URANIUM RESOURCES EVALUATION PROJECT I U R E P NATIONAL FAVOURABILITY STUDIES IUREP CT.F.S. No. 161 FALKLAND ISLANDS CONTENTS Page 1 B. GEOLOGY IN RELATION TO POTENTIALLY FAVORABLE URANIUM-BEARING AREAS G. PAST EXPLORATION D. URANIUM OCCURRENCES AND RESOURCES E. PRESENT STATUS OF EXPLORATION P. AREAS FAVORABLE FOR URANIUM MINERALIZATION AND POTENTIAL FOR NEW DISCOVERY 2 BIBLIOGRAPHY 3 MAP OF FALKLAND ISLANDS A. INTRODUCTION (a) Geography The treeless Falkland Islands and dependencies are a British crown colony of about 200 islands that are located between 51 -53 S. longi- tude and between 57°-62° W. latitude, 480 kilometers east of the South American mainland. Most of the 12,180-square-kilometer area is contained in the two main islands East and West Falkland. The capital is Stanley (Port Stanley) on East Falkland, The dependencies comprise island groups 1,126 to 3,218 km. east and southeast of Port Stanley; they include_ South Georgia and che South Sandwich Islands. Two east-west folds extend across the northern portions of the islands, and ranges of hills along these folds may rise to 701 meters. Small, sluggish rivers occupy broad, peat-covered valleys. (b) Climate Temperatures average -4° to 18° C, and strong westerly winds are present. Rain falls rather evenly throughout the year with an annual average of 63 centimeters. (c) Transportation The capital, Port Stanley, has 19 km, of concrete roads, but elsewhere only unsurfaced tracks are available for dry weather use. JTra£S£ortatiori around the islands__is provided by government ships to Montevideo, Uruguay. (d) Other Argentina has claimed the Falkland Islands as the Islas Malvinas since the 18th century. B. GEOLOGY IN RELATION TO POTENTIALLY FAVORABLE URANIUM-BEARING AREAS The rocks of the Falkland Islands range in age from (?) Precambrian to (?) Jurassic or Lower Cretaceous. A thick succession of marine and terrestrial Paleozoic sediments rests unconformably on a supposed Pre- cambrian basement in West Falkland. These Paleozoic rocks are also present in the northern half of East Falkland, whereas to the south they pass upwards into a thick succession of Permo-Triassic sediments contain- ing plant fossils. The'sediments of West Falkland are intruded by numerous basaltic dikes of Jurassic or (?) early Cretaceous age. The Precambrian rocks, known as the Cape Meredith Complex or Series, have been assigned to the Archean. They form a very limited outcrop in the extreme south of West Falkland. They consist of crystalline schists (to the west) and gneisses (to the east) both of which are intruded by granites, lamprophyre and other dikes and acid pegmatites. Xenotime, a uranium-bearing phosphate, occurs but rarely in the pegmatites. The lowermost Paleozoic rocks comprise a series of Devonian- Carboniferous sediments, the oldest of which are coarse-grained unfossiliferous sandstones, quartzites, and conglomerates about 1,600 meters thick. The sandstones are red and yellow in color, exhibit cross- bedding, and are massive to thickly bedded. The overlying middle section of Devonian-Carboniferous sediments is made up of interbedded micaceous sandstones and slaty shales, and contains fossils of marine fauna, mainly brachiopods. Above this are Middle Devonian sediments containing plant fossils. These in turn are succeeded by Lower Carboniferous beds consisting of a massive sequence of unfossiliferous sandstones and quartzites about 700 meters thick. The Devonian-Carboniferous Group is separated by an unconformity from an overlying Carboniferous-Permian-Triassic Supergroup (Lafonian). This consists in upward succession of tillite, sandstone, and a large thickness of alternating sandy and clayey rocks containing plant fossils. Apart from those occurring in the Precambrian rocks, the only intrusive rocks in the Falkland Islands are dolerites. 0. PAST EXPLORATION No information is available on exploration for uranium. ]>. URANIUM OCCURRENCES AND RESOURCES No information could be found on uranium occurrences or resources, and it is presumed there are none. K. PRESENT STATUS OF EXPLORATION No exploration for uranium is known to be in progress on the islands. F. AREAS FAVORABLE FOR URANIUM MINERALIZATION AND POTENTIAL FOR NEW DISCOVERY . "••••- The Precambrian rocks are presumably Archean and thus present little potential for uranium. The xenotrme-bearing pegmatites may warrant further study. ^ However, because the mineral is described as occurring rarely, there is little likelihood of economic quantities. The sandstones bearing plant fossils may merit examination, particularly where the beds are of fluviatile or marginal marine origin. There seems to be little justification at present for concluding that the Falkland Islands offer good prospects for uranium, and the potential is therefore estimated to be less than 1,000 tonnes. BIBLIOGRAPHY Greenway, M. E., 1972, The geology of the Falkland Islands; British Antarctic Survey, Sci. Rpt. No. 76, Natural Environment Research Council, London. Compiled hy USKRDA January 1978 EJ«V«(K m in nratres FALKLAND ISLANDS ATLANTIC I OCEAN 52 am r 5.0 km 60 mi S7? C Rind MtNally t Co. 58?.