Climatic versus tectonic factors in the formation of the glaciolacustrine succession (Bełchatów outcrop, central Poland)

Abstract

Pleistocene glaciolacustrine sediments of the Kleszczów Graben (the Bełchatów outcrop, central Poland) record the origin, development, and decay of a glacial lake formed in the area of a subsiding basin during the advance of the Elsterian ice sheet. The sediments represent a transition from glaciofluvial to glaciolacustrine facies at the bottom part, and from glaciolacustrine to glacial facies at the top. The glaciolacustrine facies represent a few environments inside the lake basin, from the marginal sub-aqueous slope through the bottom part to the sub-aqueous fan. The contact of the glaciolacustrine facies and the overlying glacial till is erosional, and implies that a considerable part of the shallow-water lake facies was eroded. The lake existed for not longer than 600 years, but its development proceeded under the conditions of the Kleszczów Graben subsidence and the approach of the Elsterian ice sheet. Both factors influenced the sedimentation processes. The tectonic and climatic factors were recognised on the basis of facies analysis of lithofacies associations, and of their vertical and lateral changes.