Terrace styles and timing of terrace formation in the Weser and Leine valleys, northern Germany

Response of a fluvial system to climate change and glaciation

authored by

Jutta Winsemann, Jörg Lang, Julia Roskosch, Ulrich Polom, Utz Böhner, Christian Brandes, Christoph Glotzbach, Manfred Frechen

Abstract

In glaciated continental basins accommodation space is not only controlled by tectonics and sea-level but also by the position of ice-sheets, which may act as a regional base-level for fluvial systems. Although the Pleistocene terrace record of major river systems in northwestern Europe has been investigated by many authors, relatively little attention has been paid to base-level changes related to glacier advance-retreat cycles and how these regional changes in base-level interacted with river catchment processes. This study provides a synthesis of the stratigraphic architecture of Middle Pleistocene to Holocene fluvial terraces in the upper Weser and middle Leine valley in northern Germany and links it to glaciation, climate and base-level change. The depositional architecture of the fluvial terrace deposits has been reconstructed from outcrops and high-resolution shear wave seismic profiles. The chronology is based on luminescence ages, ²³⁰Th/U ages, ¹⁴C ages and Middle Palaeolithic archaeological assemblages.The drainage system of the study area developed during the Early Miocene. During the Pleistocene up to 170m of fluvial incision took place. A major change in terrace style from strath terraces to cut-and-fill terraces occurred during the early Middle Pleistocene before Marine Isotope Stage MIS 12, which may correlate with climate deterioration and the onset of glaciation in northern central Europe. During this time a stable buffer zone was established within which channels avulsed and cut and filled freely without leaving these vertical confines. Climate was the dominant driver for river incision and aggradation, whereas the terrace style was controlled by base-level changes during ice-sheet growth and decay. A major effect of glacio-isostatic processes was the post-Elsterian re-direction of the River Weser and River Leine.The Middle Pleistocene fluvial terraces are vertically stacked, indicating a high aggradation to degradation ratio, corresponding with a regional base-level rise during glacier advance. At the beginning of the Late Pleistocene the terrace style changed from a vertical to a lateral stacking pattern, which is attributed to a decrease in accommodation space during glacier retreat. The formation of laterally attached terraces persisted into the Holocene.Major incision phases took place during MIS 5e, 5d, 5c, and probably early MIS 4, early MIS 3 and MIS 2 (Lateglacial). During MIS 5e and the Lateglacial the braided river systems changed into meandering rivers, indicated by preserved organic-rich flood-plain and point bar deposits. The Late Pleistocene braided river systems (MIS 5c to MIS 3) are characterized by a high sinuosity, which may be a direct effect of an increased downstream gradient after deglaciation when the channel lengthened and the river adjusted to the increased gradient by increasing sinuosity. These Middle Pleniglacial fluvial deposits are unconformably overlain by Lateglacial to Holocene meandering river deposits, which form laterally attached terraces, recording millennial-scale channel shifts. The lack of Late Pleniglacial deposits might be related to Late Weichselian forebulge formation.

Organisation(s)

Institute of Geology
Leibniz Research Centre FZ:GEO

External Organisation(s)

Leibniz Institute for Applied Geophysics (LIAG)
Lower Saxon State Agency of Monument Preservation

Type

Article

Journal

Quaternary science reviews

Volume

123

Pages

31-57

No. of pages

27

ISSN

0277-3791

Publication date

01.09.2015

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Global and Planetary Change, Ecology, Evolution, Behavior and Systematics, Archaeology, Archaeology, Geology

Sustainable Development Goals

SDG 13 - Climate Action, SDG 14 - Life Below Water

Electronic version(s)

https://doi.org/10.1016/j.quascirev.2015.06.005 (Access: Unknown)