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An extraordinary variation of plastic and brittle deformation structures with periglacial, glaciotectonic and seismic features was observed within the unconsolidated, upper Pleistocene meandering river succession in the Slinkis outcrop in central Lithuania. Among these deformations, the following structures were described: (1) ice-wedge casts in the lower part of the sedimentary succession, linked to periglacial processes, (2) soft-sediment deformation structures, such as load structures (load casts, pseudonodules), flame structures and water/sediment-escape structures, all trapped in clearly defined layers in the upper part of the sedimentary succession, which are related to the propagation of seismic waves, and (3) faults occurring throughout the sedimentary succession, which are associated with glaciotectonic processes. To our knowledge, this is the first description and analysis of the combined presence of such a diverse range of deformation features caused by three trigger mechanisms in a meandering fluvial sedimentary succession.

Liquefaction can cause deformation of unconsolidated sediment, but specific processes involved and the trigger mechanisms often remain obscured. This study describes multiple deformed sediment layers in a succession of lacustrine sand, silt and clay deposited during the Marine Isotope Stage 5d in north-western Lithuania. The deformation structures (load casts, pseudonodules, ball-and-pillow structures, broken-up laminae and injections) are embedded in ten separate layers of fine-grained, laterally continuous sediments. Detailed mesoscale sedimentological analyses suggest that each deformation event consisted of numerous successive stages of sediment advection facilitated by liquefaction. Low-permeability fine-grained laminae contributed to localized pore-water pressure build-up and lowering of sediment strength. Erosional top surfaces that truncate layers with soft-sediment deformation structures suggest that at least seven deformation events were separated by successive periods of initial erosion and then uninterrupted deposition in the lake. The most likely trigger of the deformation was recurrent palaeoseismic activity possibly linked to a late glacial isostatic adjustment following the Scandinavian Ice Sheet melting after the Saalian glaciation. This study emphasizes the potential role of seismic processes in shaping the sedimentary record of the intraplate region of north-eastern Europe and contributes to constraining the depth of liquefaction, regardless of the actual trigger mechanism.

Abstract. Isostatic response of the Earth's crust as a consequence of the fluctuating extent of ice-sheet masses was accompanied by earthquakes probably due to local reactivation of pre-existing faults. Our study of a glacilacustrine and glacifluvial succession exposed on Rügen Island (SW Baltic Sea) indicates that some of the soft-sediment deformation structures within the succession must have formed shortly before the front of the Pleistocene Scandinavian Ice Sheet reached the study area (during the Last Glacial Maximum), thus during a stage of ice advance. Based on analysis of the textural and structural features of the soft-sediment deformation structures, the deformed layers under investigation are interpreted as seismites which formed as a result of seismically induced liquefaction and fluidisation.

Significant quantities of ruptured pebbles are found in glaciotectonically deformed glaciofluvial sediments of the Saalian glaciation (MIS 6) at the Koczery site (E Poland). To identify the responsible mechanisms for the pebble-rupture activity, structural, petrographic, roundness and shape analyses were done. Additionally, till fabric of overlying glacial diamicton was analysed and compared to the other outcomes. The origin of fractures in ruptured pebbles of glaciofluvial sediments is directly linked to compressive stress caused by glaciotectonic processes because of 1) ruptured pebbles occur mainly in glaciotectonically deformed sediments (a quarter of all pebbles is fractured); 2) ruptured pebbles almost always occur one-by-one primarily in gravelly lithofacies; 3) fractures occur in pebbles derived from all petrographic groups; 4) fracture occurrence is independent of pebbles size, shape and roundness; 5) fractures mostly occur parallel to each other (along long 'a' or short 'c' axis of pebbles) and parallel to the bedding of lithofacies; and 6) in most cases broken fragments of ruptured pebbles survived in the host sediment indicating that the observed damage occurred in situ. This novel study of ruptured pebbles found in glacigenic environments sheds new light on the dynamics of glaciotectonic processes, and may be useful in the characterization of palaeostresses that occur during glaciotectonic deformations.