Late Pleistocene stratigraphy at Boliden, northern Sweden |
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| Authors: | ANN-MARIE ROBERTSSON KARIN GARCíA AMBROSIANI |
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| Institution: | Department of Quaternary Geology, University of Stockholm, Odengatan 63, S-113 22 Stockholm, Sweden and Geological Survey of Sweden, Box 670, S-751 28 Uppsala, Sweden;Department of Quaternary Geology, University of Stockholm, Odengatan 63, S-113 22 Stockholm, Sweden |
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| Abstract: | Till-covered sand and silt sediments with organic material from Boliden, northern Sweden, have been resampled and reinvestigated. Texture and petrographic analyses demonstrated one till bed overlying, and one underlying the sandy sediments. Low frequencies of diatoms were noted, representing freshwater, halophilous and brackish water taxa. The diatoms may be allochthonous or autochthonous, or redeposited from older deposits. Pollen analysis revealed a new picture of the composition of the vegetation, as compared with earlier investigations. The flora consisted of an arctic-subarctic treeless shrub and herb vegetation dominated by Salix, Betula nana , Gramineae and Cyperaceae. Artemisia and several arctic-alpine herbs were important elements. The identification of Salix wood as well as fruits and fruit scales of Betula nana and Betula cf. humilis is in agreement with the pollen-analytical results, as is the occurrence of Nordicboreal species of Coleoptera. Two radiocarbon datings resulted in an age of c. 45,000 B. P. and >40,000 B.P. The Boliden till-covered sediments were most probably deposited during an Early or Middle Weichselian interstadial, but the initial or final stage of an interglacial (Eemian) is also possible. |
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