Climatic control on Quaternary fluvial sedimentology of a Fenland Basin river, England

Understanding and interpreting climate response from ancient fluvial deposits requires a combined approach of detailed sedimentological description and interpretation, local climate proxies, and the accurate comparison of these sequences with further independent climate records. Application of these multiple lines of evidence is particularly effective in the Quaternary Period, where higher resolution and more detailed palaeoenvironmental reconstruction are possible. This paper presents results from a Devensian (Weichselian) age sequence in northern Fenland, England, that integrates these approaches. Detailed sedimentological description has identified three fluvial facies associations overlain by a period of ice-wedge cast formation. Fossil plant and coleopteran material within these sediments have been studied to provide palaeoenvironmental reconstructions for the local landscape, including quantitative temperature estimates using the mutual climatic range method on fossil Coleoptera. In addition, joint application of radiocarbon and optically stimulated luminescence (OSL) dating allows this sequence to be compared with the stacked marine isotope record, although dates do not agree well at the limit of the radiocarbon technique. Sedimentological interpretations, palaeoenvironments and global ice-volume variations (a proxy for climatic severity) are all in agreement and show clearly how the River Nene responded to subtle changes in climate and vegetation cover during the Devensian (Weichselian) Stage. The level of detail possible in this reconstruction shows the importance of this approach in understanding fluvial response to past climate changes.