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The evolution of a Weichselian proglacial lake in NW Poland as revealed by static penetration tests

Wierzbicki Jędrzej, Paluszkiewicz Renata, Paluszkiewicz Ryszard

Geologos

2011

Vol. 17, No. 2

111--119

The lithology, structure and geophysical characteristics of the glaciolacustrine clays deposited in the Wierzchowo proglacial lake were determined using static penetration tests (CPTU) in combination with standard lithological measurements. The deposits are divided into four lithological units (R1 to R4) on the basis of overconsolidation. Units R3 and R4 are separated by mass-flow deposits. The depositional conditions history of the lake result represent four phases: (1) an initial (low-energy) phase with the deposition of the rhythmically laminated sediments of units R1 and R2, which are divided by an erosional interval; (2) a phase of non-deposition with some desiccation structures and extended consolidation of sediments; (3) the main phase characterised by deposition of the rhythmically laminated sediments of unit R3; and finally, (4) the youngest phase, which represents alternations of deposition and erosion. The results show that sedimentation in the Wierzchowo proglacial lake was less continuous, and that the depositional processes were more complex than in the neighboring Złocieniec glacial lake.

Development and infill of Vistulian glacial Lake Gniew (N Poland) : a sedimentological analysis

Błaszkiewicz M., Gruszka B.

Geological Quarterly

2005

Vol. 49, No. 4

449--462

A substantial glaciolacustrine unit in northern Poland, between the valleys of the Vistula and Wierzyca rivers, was deposited in glacial Lake Gniew during the climatic amelioration of the Late Vistulian. It covers an area of 35 km2 and has an average thickness of 7m, but locally reaches over 20 m. Four sedimentary facies are distinguished. The silty/clayey rhythmites of facies A are interpreted as varves from the central lake bottom. They represent the initial stage of lake development. Facies B is formed by a single sand layer that is interpreted as a turbidite originating during lake shallowing due to self-drainage. Facies C consists of massive clay with dropstones and dump structures. Two hypothesis regarding its genesis are put forward: the first assumes sedimentation in a shallow basin with a high input of homogenous fine-grained suspended sediment, whereas the second explains the facies as a result of amuddy jökulhlaup, pouring into Lake Gniew and being sourced from another glacial lake; further research is required to interpret this facies reliably. Facies D consists of thick silty/clayey rhythmites that are interpreted as prodeltaic deposits.