Sedimentary record of the younger saalian ice margin stagnation in eastern poland: development of a regular pattern of glaciolacustrine kames

Abstract

of the younger Saalian ice margin stagnation in eastern Poland: development of a regular pattern of glaciolacustrine kames. Geografiska Annaler: Series A, Physical Geography, ABSTRACT. Glaciolacustrine kames in the Bielsk Podlaski area (eastern Poland) exhibit a unique regular pattern. Three representative morphological kame types were chosen for detailed sedimentological analyses, specifically: isolated, isometric mounds; isolated, elongated hills; and branching ridges. All types comprised fine-grained sandy and sandy/ silty deposits. Lithofacies analysis resulted in the distinction of several lithofacies associations. Associations dominated by medium-or large-scale, massive or horizontally laminated sands are interpreted as proximal subaqueous fans; associations dominated by medium-or small-scale lithofacies of ripple-drift cross-laminated sand are interpreted as distal subaqueous fans; and those dominated by sandy/silty, silty or silty/clayey lithofacies with horizontal lamination are interpreted as lake bottomsets. Rates of sediment accumulation appear to have been fast, resulting in syndepositional and metadepositional deformation structures of two types: water-escape structures, and slumps on subaqueous slopes. After the ice-walled lake basins filled with sediment, glaciofluvial erosion and deposition alternated, resulting in erosional channels of up to 1 m deep, later filled with gravel or gravely sand. The results indicate that kames developed in a supraglacial environment within a topography of ice-cored moraines containing ice-walled lakes that persisted due to the presence of permafrost. Pauses during retreat of the ice walls resulted in ice-contact deformations at the edges of the kames. Kame formation is therefore consistent with a continental climate and this may explain the increased abundance of this type of kame system in Eastern Europe.

The Middle Pleistocene glaciolacustrine environment of an ice‐dammed mountain valley, Sudeten Mountains, Poland

“…) in the central Polish Lowlands. In eastern Poland, Gruszka & Terpiłowski () described the sedimentary record of the stagnation of the Younger Saalian ice margin from kame deposits. In the northern part of Poland and Germany, at the Vistulian (Weichselian) ice margin, varves and megavarves have been found only in the Eberswalde Valley, NE Germany (Pisarska‐Jamroży ) and in Pomerania, e.g.…”

“…Kame delta architecture (Winsemann et al . , b; Gruszka & Terpiłowski ; Wachecka‐Kotkowska ) may be similar to one created in strictly glacial environments or even in ice‐contact situations (Feenstra & Frazer ), and interbedded diamictons of glacial origin (tills) would be expected.…”

Topography and melting dynamics of ice‐cored ridges: evidence from the geometry, kinematics and sedimentary evolution of collapse structures within kame deposits, eastern Poland

“…the toe of the lake slope (Gilbert 1975) of a prograding subaqueous fan or delta, commonly documented in Pleistocene glacial deposits (e.g. Winsemann et al 2004;Błaszkiewicz & Gruszka 2005;Godlewska & Terpiłowski 2012;Gruszka & Terpiłowski 2015).…”

“…Hambrey et al . ; Huddart & Bennett ; Gruszka & Terpiłowski ). Two assumptions have been made to reconstruct the linearity and regular spatial arrangement of ice‐cored ridges controlled by the internal structure of the parent ice: first, that the resulting landforms should be manifested as crudely aligned topographic features more or less parallel to the ice‐sheet margin; and second, that the depressions developing between ice‐cored ridges can influence the spatiotemporal pattern of supraglacial deposition and thus the distribution of the resulting lithofacies.…”

“…The topography and melting dynamics of ice-cored ridges have been reconstructed for marginal zones of the Pleistocene ice sheets based only on conceptual and qualitative models supported by geomorphological, sedimentological and palaeogeographical studies (e.g. Hambrey et al 1997;Gruszka & Terpiłowski 2015). Two assumptions have been made to reconstruct the linearity and regular spatial arrangement of ice-cored ridges controlled by the internal structure of the parent ice: first, that the resulting landforms should be manifested as crudely aligned topographic features more or less parallel to the ice-sheet margin; and second, that the depressions developing between ice-cored ridges can influence the spatiotemporal pattern of supraglacial deposition and thus the distribution of the resulting lithofacies.…”