Compositional variability of Saalian till in The Netherlands and its origin

Abstract

Variations in composition between and within Saalian till types of The Netherlands arc dcmonstratcd with reference to grain-size distribution, fine-gravel petrography and heavy-mincrzl compo\ititrn. Several factors explain different aspects of the compositional variations. Firstly, a compositional layering rcsults from differcnces in the amount of local material that has been assimilated in successivc till hand\. Secondly, a petrographic stratification is present in the erratic components, which is most \trikingly expressed by the occurrence of flint-poor till ovcrlying till rich in flints. This fcaturc is in:crprctcd to havc becn inherited from an cnglacial debris stratification which is related to thc distribution of source rock types in the up-glacier area. Finally. a predominantly lateral variation in till compobirion 15 prcscnt.reflected best in the assemblages of the indicator pebbles, resulting from deposition by icc streams of different source and direction of flow.

Composition and source of the clay‐sized fraction of Saalian till in The Netherlands

“…Therefore, much of the flint-poor till is most probably transported englacially from the East and East-Central Baltic and deposited basally without any local influence. The clay mineralogy thus indicates that the conclusions about englacial transports assumed by Ehlers (1981Ehlers ( , 1983 and Rappol & Stoltenberg (1985) in many places are valid for the entire till and not just for the coarse components. The englacial transport, as related to the source areas in the East and East-Central Baltic, must have been at least 1000 km and, for parts of the material, considerably longer.…”

“…The till classification, which is primarily based on flint content and the composition of crystalline indicator gravel assemblages, shows that strong and consistent regional variations are observed in the Fennoscandian indicator assemblages (Zand-stra 1987) that may partly correspond to different directions of ice movement in The Netherlands (e.g. Rappol & Stoltenberg 1985;Rappol 1987;Zandstra 1987).…”

“…1). Based on studies of the gravel and sand material of the tills, Rappol & Stoltenberg (1985) and Rappol (1987) assumed that this petrographical stratification is a result of the glacial transport. They believed that the distant flint-poor material became dispersed upwards in the ice during the transport, while the less far transported material was enriched in the lower part of the ice.…”

Heavy-mineral derived provenance study of Quaternary sediments of the Mazovian Lowland, Central Poland

“…These sediments have multiple sourcing, because the delivery system by the ice sheet might have been complex and multidirectional (Woźniak, Czubla 2015). The garnetamphibole enhancement has been observed in the numerous Saalian glacial sediments (Czerwonka et al 1997;Ludwikowska-Kędzia 2013;Rappol, Stoltenberg 1985;Woronko et al 2013), which likely supports their Fennoscandian origin resulting from the ice advance (cf. Woronko et al 2013).…”

Heavy minerals as a tool to reconstruct river activity during the Weichselian glaciation (Toruń Basin, Poland)

“…The heavy-mineral assemblage of the tills consists commonly of garnet (15-35%), amphibole (5-25%) and biotite (up to 30%), whereas amphibole (10-35%) dominates over garnet (15-30%;Racinowski, 2010) in the glaciofluvial sands. A similar high amount of amphibole and garnet derived from Palaeozoic and Precambrian rocks in the eastern central Baltic was found in Saalian tills in The Netherlands and in Weichselian tills in north-eastern Germany (Rappol & Stoltenberg, 1985;Haldorsen et al, 1989;Górska, 2006). The deposits of the rivers which were not fed by meltwater are characterised by the domination of garnet (30-45%) and in most cases an insignificant amphibole and biotite content (less than 10%: Racinowski, 2010).…”