Heavy minerals as a tool to reconstruct river activity during the Weichselian glaciation (Toruń Basin, Poland)
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Date
2013-05-20
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Publisher
Wydawnictwo Naukowe UAM
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Abstract
The heavy-mineral composition of the Weichselian fluvial successions deposited by an ephemeral meandering river
and by a sand-bed braided river in the Toruń Basin (central Poland) was analysed. On the basis of a lithofacies analysis,
in combination with the composition of the heavy-mineral assemblages, the fluvial processes and river-channel morphology were reconstructed. This allows determining the provenance of the fluvial deposits and the rivers’ discharge regimes. A model is proposed which can explain the changes in the amount of individual minerals in the fluvial sediments of different ages under the conditions of the oscillating Scandinavian ice sheet. The model assumes that, during
the ice-sheet advances, the proglacial streams supplied large amounts of heavy minerals that were less resistant to
mechanical abrasion. During the main phase of the ice-sheet retreat, the distance between the ice sheet and the Toruń
Basin increased, and the amount of non-resistant minerals diminished as a result of sediment reworking in proglacial
rivers. Due to the unique location of the Toruń Basin at the front of the Scandinavian ice sheet during the Weichselian
glaciation, the heavy–mineral assemblages in the fluvial deposits form a valuable tool for the recognition of the ice-sheet
extent.
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Keywords
Heavy minerals, Ice-marginal valley, River-discharge regime, Channel-pattern transformation, Toruń Basin, Weichselian
Citation
Geologos, 2013, vol. 19, 1, pp. 25-46.
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ISBN
978-83-232187-4-6
ISSN
1426-8981