Pre-Late Weichselian fossils at Kvalsundet near Tromsø, north Norway

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1 Pre-Late Weichselian fossils at Kvalsundet near Tromsø, north Norway TORE O. VORREN Vorren, T. 0.: Pre"Late Weichselian fossils at Kvalsundet near Tromsø, north Norway. Norsk Geologisk Tidsskrift, Vol. 59, pp Oslo ISSN 0029"196X. Reworked molluscs, foraminifera, and palynomorphs occur in a basal ti U at K valsundet near Tromsø. The fossils, e.g. Arctica islandica, Cardium ciliatum, indicate a contemporaneous low"arctic environment as opposed to the present high"boreal environment. The fossils were "C"dated to 40, BP. Environmental implications and correlation with other finds are briefly discussed. T. O. Vorren, Institutt for biologi og geologi, Universitetet i Tromsø, Postboks 790, 900 Tromsø, Norway. Fossilieferous deposits of Quatemary age occur at Kvalsundet, north of Tromsø (Fig. lb). The sediments are exposed in a road section, 2-4 m a.s.l., and they can be traced along the section for more than 2 km. The thickness of the sediments varies and is in some places at least 5 m. Lithology The sediments are well consolidated, and generally massive but with lenses of siltsand. The grain-size distribution of fractions below 16 mm reveals a very poorly sorted, nearly symmetrical, and very leptokurtic sediment, Fig. 2. The primay mode is located in the very coarse silt grade (5 to 4 phi). Based on a four grade roundness-scale (Bergersen 1973), grains in the 4-8 mm grades were classified as 61% angular, 38% subangular, l% rounded and none well rounded. Some of the grains have been rounded and later crushed. Fabric analysis showed that stones having a pronounced long-axis were aligned NE SW. Petrographically, most of the clasts are plagioclase-rich gneisses and amphibolitic gneisses. In the area under consideration these are also the predominant components of the bedrock. Some shell fragments are found. The ela y fraction ( < 2 IJ-) comprises mainly illite, but some chlorite and small amounts of amphibole and plagioclase occur. The structure, texture, and composition indicate that the sediment is fairly locally derived basal till deposited from a glacier flowing northwest through K valsundet. The con tent of shell fragments and the very leptokurtic grain-size distribution caused by the high content of very coarse silt indicate that much of the material is derived originally from marine deposits. Fossils Macrofossils. - Shell fragments were collected along about 100 m of the road cut. No whole shells were found. The following fragments were identified: Arctica islandica (L.) (low-arcticboreal) Astarte cf. elliptica (Brown) (arcticboreal) Astarte sp. Chlamys islandica (Muller) (arcticmid-boreal) Cardium ciliatum (Fabricius) (arctic) Mya truncata (L.) (arcticlusitanian) Baanus cf. crenatus (Bruguiere) (arcticlusitanian) Leieschara cf. coarctata (M. Sars) (arctic bo real) Lithothamnion cf. thophiforme (Unger) (arctic high boreal) The present distribution (given in brackets) is according to Feyling-Hanssen (1955), Ockelmann (1958), Kluge (1975) and Rueness (1977). The zoogeographical regions used are in agreement with the definitions given by Feyling-Hanssen (1955) (Fig. la). The present northem boundary of A. islandica is the White Sea, while the present southem boundary of C. ciliatum is the east coast of Finnmark. If these two fossils lived in the same time span, they thus indicate a low-arctic environment (Fig. la). Conceming water depth, most of the fossils found live at present at depths below 10 m. Kluge (1975) indicated 24 m as an upper bound-

102 Note NORSK GEOLOGISK TIDSSKRIFT l (1979) HIGH- ARCTIC B 10 km RINGVASSØY ARCTIC, ' ' ', BJørnøya t------ - --- LOW-ARCTIC Fig.. Location maps. A. The zoogeographical division of the northern European seas, after Feyling-Hanssen ( 1955).

2 102 Note NORSK GEOLOGISK TIDSSKRIFT l (1979) HIGH- ARCTIC B 10 km RINGVASSØY ARCTIC, ' ' ', BJørnøya t LOW-ARCTIC Fig.. Location maps. A. The zoogeographical division of the northern European seas, after Feyling-Hanssen ( 1955). B. The ice margins of the Weichselian ice sheet during the Skarpnes event (SK) (about 12,000-12,500 BP) and Tromsø Lyngen event (T-L) (about li,000-10,000 BP), after Andersen (1968). The investigated locality (cross) is situated distally to the se Late Weichselian ice margins. The hatched area denotes the occurrence of the fossiliferous sediments. CLAY SILT SAND GRAVE L l 99 l ' 50 7,. 7 " " M, or sk Kg ,---,----, ,----, > Fig. 2. Cumulative grain-size distribution of the fossiliferous sediments from Kvalsundet drawn on probability percent ordinate. The grain-size parameters are calculated according to Folk & Ward's ( 1957) formulae.

3 NORSK GEOLOGISK TIDSSKRIFT l (1979) Note 103 ary for L. coarctata. C. ciliatum does not occur above 22 m in east Finnmark, while in east Greenland this species is mostly found at depths between lo and 40 m (Ockelmann 1958: 120). L. thophiforme normally lives at depths above 40 m (E. Jaasund, pers. comm.). The macrofossils thus indicate a water depth between 20 and 40 m. Microfossils. - Foraminifera were extracted from sample 21-76, fraction l mm, using bromoform (s.g. = 1.9). K. Ofstad kindly analysed the foraminifera. Species Frequency Percentage Cibicides lobatulus Cassidulina crassa Ephidium excavatum f. clavata 32 Il Jsandiella norcrossi 22 8 lslandiella heenae 19 7 Elphidium excavatum f. alba 12 4 Astrononion galoway 6 2 Bulimina marginata 4 Bue cella frigi da 3 Elphidium bartet ti 2 <l Elphidium umbilicatulum 2 <l Elphidium sp. 2 <l Nonion abradoricum 2 <l Trifarina angulosa 2 <l Bolivina pseudopicata <l Elphidium cf. groenlandicum <l Ephidium macellum <l Gavelinopsis praegeri <l Gandulina sp. <l Isandiela islandica <l Oolina acuticosta <l Protephidium sp. <l Pullenia sp. <l Stainforthia loeblichi <l Trifarinajluens <l In I 00 g of sediments the number of specimens is 480. The fauna! diversity, according to Walton (1964), is 12. The specimens were somewhat corroded, thus some identifications may be uncertain. The dominating species, Cibicides lobatulus, has at present a cosmopolitan distribution, at moderate depths in rather cool water (Feyling-Hanssen 1%4:339). Cassidulina crassa and Elphidium excavatum f. clavata are most frequently found in arctic environments (Knudsen 1971 :246, Feyling Hanssen 1972:337). Also most of the other species found have affinities with arctic environments. Bulimina marginata, Trifarina angulosa, and Elphidium macellum represent, however, a boreal environment. The foraminifera assemblage thus indicates low-arctic conditions and moderate depth, which is in accordance with the macrofossil assemblage. Palynomorphs were extracted from sample according to the method described by Vorren (1972). The following 30 specimens were registered: Betula 6 Chenopodiaceae l Ericales 3 Varia-pollen (NAP-types) 2 Dryopteris linneanea type 3 Filices 13 Lycopodium annotium type 2 The content of palynomorphs is so low that no certain conclusion can be drawn. There is, however, no discrepancy between the marine fossil assemblage and the palynomorph assemblage; both indicate low-arctic environments. The relatively high spore content may indicate a relatively humid climate. Radiocarbon-dating. - Some of the )argest fragments of the macrofossils, 24.7 g mostly of A. islandica and M. truncata, were 14C-dated at Laboratoriet for radiologisk datering, NTH, Trondheim. The outer part of the shells (c. 20%) was removed by etching with diluted HCL. The age, corrected for isotopic fractionation to C13 =0%o PDB, was 40, B.P. (T- 2377). Discussion Environment. - Compared with their present distribution, the marine fossils indicate that they Iived in a low-arctic environment about m depth. If the sediments have not been transported in a vertical direction, this indicates that the shore leve! was somewhat higher than at present. The Iow-arctic subregion is at present highly influenced by Atlantic water (Feyling Hanssen 1955). Thus the fossils suggest the presence of the North Atlantic current when they lived here. A low-arctic marine environment probably implies a more severe terrestrial climate, compared with the present high-boreal conditions, and this would imply that larger areas were glaciated. A pronounced local glaciation possibly occurred on the outer islands, while a continental ice sheet may have existed on the inner mainland areas as in Late Weichselian (Andersen 1%8).

4 104 Note NORSK GEOLOGISK TIDSSKRIFT l (1979) Age and correlation. - Due to uncertainties in radiocarbon dating of shells older than 20,000 years (Mangerud 1972), the possibility of a dif ferent age, probably older, for the Kvalsundet fossils must be considered and an Early WeichselianEemian age cannot be excluded. Assuming the 14C-date is correct, it indicates a Middle Weichselian Age for the fossils. In Norway some finds of assumed Middle Weichselian age are known (Andersen 1%5, Mangerud 1972a, Bergersen & Garnes 1971, Feyling-Hanssen 1971, 1974), and several others are known from elsewhere in Europe (e.g. Lundquist 1974, Coope 1975, van der Hammen et al. 1971). The marine sediments and fossils from Jæren and adjacent areas are of special interest in this connection. Radiocarbon datings of these give ages between 28,000 and 42,000 BP (Mangerud 1972b). Thorium-uranium datings partly confirm this age, but some of the fossils had higher ThU-ages, viz. about 76,000 ± 11,000 BP (Nydal 1975). Feyling-Hanssen (1971, 1974) made a detailed investigation of the Jæren foraminifera and concluded that many of the finds belong to a Middle Weichselian interstadial, the so-called Sandnes interstadial, which occurred sometime during the interval between 20,000 and 50,000 BP. The marine environment during the Sandnes interstadial was found to be low-arctic to high-boreal. The fossils from K valsundet may be correlatable with the Sandnes interstadial. If so, this implies that large coastal areas of Norway were not glaciated at that time (Vorren 1977). Conclusion Rebedded fossils in basal till are found at Kvalsundet near Tromsø. The fossils (e.g. Arctica islandica, Cardium ciliatum) indicate lowarctic condition at their time of li ving. Radiocarbon-dates of the shells gave an age of 40, B.P. Due to uncertainties with such old radiocarbon dates an earlier age may be possible. If the radiocarbon date is correct, this tind, together with other occurrences from Middle Weichselian in south Norway, indicates that large areas of the Norwegian coast were not glaciated during periods of Middle Weichselian and that Atlantic water was probably present off the Norwegian coast at!east as far north as Troms during that period. Acknowledgements. - The present paper is a contribution to the IGCP Project 'Quaternary Glaciations in the Northern Hemisphere', which is financially supported by the Norwegian Research Council for Science and the Humanities. K. Cmchow, cand. real. K. Ofstad, cand. real. A. Elvsborg, førsteamanuensis J. Nagy and universitetslektor K. -D. Vorren helped with the identification of fossils and the laboratory work. The figures were drawn by H. Falkseth. To all these persons I proffer my sincere thanks. References September 1977 Revised January 1979 Andersen, B. G. 1965: The Quaternary of Norway, n Rankama. K. (ed) The Quaternary, Vol. l. John Wiley & Sons Ltd. N. Y. Andersen, B. G. 1968: Glacial geology of western Troms, North Norway. Nor. Geo. Unders. 256, 160 p. Bergersen, O. Fr. 1973: The roundness analysis of stones. A neglected aid in till studies. Bull. Geo. Inst. Univ. Uppsala, New Ser. 5, Bergersen, O. Fr. & Garnes, K. 1971: Evidence of Sub-till sediments from a Weichselian interstadial in the Gudbrandsdalen valley, central east Norway. Nor. Geogr. Tidsskr. 25, Coope, G. R. 1975: Climatic fluctuations in northwest Europe since the last Interglacial, indicated by fossil assemblages of Coleoptera. Geo. J. Spee. Iss. 6, Feyling-Hanssen, R. W. 1955: Stratigraphy of the marine Late-Pleistocene of Billefjorden, Vestspitsbergen. Nor. Polarinst. Skr. 107, 186 p. Feyling-Hanssen, R. W. 1964: Foraminifera in Late Quaternary deposits from the Oslofjord area. Nor. Geo. Unders. 225, 383 p. Feyling-Hanssen, R. W. 1971: Weichselian interstadial foraminifera from the Sandnes-Jæren area. In Feyling-Hanssen. R. W., Jørgensen, J. A., Knudsen, K. L. & Andersen, A.-L. L. 1971: Late Quaternary foraminifera from Vendsyssel, Denmark and Sandnes, Norway. Bull. Geo. Soe. Den. 21, Feyling-Hanssen, R. W. 1972: The foraminifer Elphidium exeavatum (Terquem) and its variant forms. Mieropaeontol. 8, Feyling-Hanssen, R. W. 1974: The Weichselian section of Foss-Eigeland, south-western Norway. Geo. For. Stoekh. Forhand. 96, Folk, R. L. & Ward, W. C. 1957: Brazo River Bar: a study in the significance of grain size parameters. J. Sed. Petr. 27, Kluge, G. A. 1975:Bryozoa of the Northern Seas of the USSR. Amerind Publ. Co. Pvt. Ltd. New Dehli, 711 p. Knudsen, K. L. 1971: Late Quatemary foraminifera from Vendsyssel, Denmark and Sandnes, Norway. Systematic part. In Feyling-Hanssen, R. W., Jørgensen, J. A., Knudsen, K. L. & Andersen, A.-L. L. 1971: Late Quaternary foraminifera form Vendsyssel, Denmark and Sandnes, Norway. Bull. Geo. Soe. Den. 21, Lundqvist, J. 1974: Outlines of the Weichsel Glacial in Sweden. Geo. For. Stoekh. Forhand. 96, Mangerud, l. 1972a: The Eemian Interglacial and the succession of glaciations during the Last lee Age (Weichselian) in southem Norway. Ambio. Spee. Rep

5 NORSK GEOLOGISK TIDSSKRIFT l (1979) Note 105 Mangerud, J. 1972b: Radiocarbon dating of marine shells, including a discussion of apparent age of Recent shells from Norway. Boreas, Nydal, R. 1975: Thorium-uranium dating of marine deposited calcium-carbonate. Paper presented at lnt. Conf. on Low Radioactivity Measurements and Applications. Tatranska Lomica, Czechoslovakia. Ockelmann, W. K. 1958: The zoology of East Greenland. Marine Lamellibranchiata. Medd. Grønland 122 (4), 256 p. Rueness, J. 1977: Norsk ageflora. Universitetsforlaget, Oslo. Soot Ryen, T. 1951: New records on the distribution of marine Mollusca in northern Norway. Astarte, l l pp. Vorren, T. O. 1972: Interstadial sediments with rebedded interglacial pollen from ioner Sogn, West Norway. Nor. Geo. Tidsskr. 52, Vorren, T. O. 1977: Weichselian ice movement in South Norway and adjacent areas. Boreas 6, Walton, W. R. 1964: Recent foraminiferal ecology and paleoecology. In Imbrie, J. & Newell, N. D. (eds.) Approaches to Paleoecology. Wiley & Sons. N.Y.

A shore displacement curve from the Tromsø district, North Norway

A shore displacement curve from the Tromsø district, North Norway MORTEN HALD AND TORE O. VORREN Hald, M. & Vorren, T. 0.: A shore displacement curve from the Tromsø district, North Norway. Norsk Geologisk