Sensitivity of Weichselian fluvial systems to climate change (Nochten mine, eastern Germany)

Abstract

This paper aims to contribute to the understanding of fluvial system response to climate change during the last glacial–interglacial cycle. Fluvial and aeolian successions have been studied in the opencast brown-coal mine Nochten in eastern Germany. An absolute chronology was established by luminescence and 14C-dating, enabling to demonstrate the relations between depositional units and changes in sedimentary environment over time with regional climatic and vegetational changes. It is concluded that the major climatic periods, coinciding with the oxygen isotope stages, are generally reflected in the fluvial sequence by distinct fluvial environments. Major climatic changes (oxygen isotope stage boundaries) have been preserved in the fluvial record as erosional bounding surfaces and by changes in fluvial style. Rapid climate changes like the Middle Pleniglacial Dansgaard–Oeschger cycles are in general not reflected in the fluvial succession. These cycles were too short or with too low amplitude to cause a strong vegetational response and related changes in water and sediment supply. It is emphasized that also the preservation potential of short-lived climatic warming events in ‘high-energy’ fluvial systems is low. Warming events may, however, have been preserved in lacustrine successions in former thermokarst lakes. A strong cooling event at ca 40 ka, leading to continuous permafrost conditions and changes in the water and sediment budget, was reflected in the fluvial archive by a change from sandy anabranching to braided river conditions.