Reconstruction of the Late Glacial and Holocene deglacial history of Synndalen, Svalbard

Abstract

Due to their sensitivity to changes in climate and the imprints they leave behind in the landscape, glaciers are important for paleoclimate reconstructions. The distribution and ages of landforms in the modern landscape can provide understanding of patterns and processes of glaciation during the past. This study contributes to an enhanced understanding of Svalbard’s deglaciation by investigating Synndalen, a deglaciated valley on Svalbard with two well constrained ice-marginal landforms. Here, the Late Glacial and Holocene deglacial history of Synndalen are reconstructed based on its geomorphological evolution. A detailed geomorphological map is presented based on in-field and remote geomorphological mapping and a spatiotemporal framework of glacial events is constructed based on absolute and relative dating methods. Radiocarbon ages of three marine bivalve molluscs are presented, ranging between 10251 and 10532 14C yrs BP, and have been calibrated to 11.3-11.7 cal. ka BP. These ages provide a minimum age constrain for the deglaciation of the Synndalen valley-mouth. This study shows that Synndalen’s deglaciation has been interrupted by two readvances. A minor retreat and advance cycle at the valley-mouth resulted in the formation of an end moraine and is considered to have been mainly dynamically driven. Very approximate age constraints constrain this advance to the Younger Dryas interstadial, although the importance of further research is emphasized. A readvance at the valleyhead formed another moraine and adds to the increasing number of identified Early Holocene readvances on Svalbard. As the climate on Svalbard during the Early Holocene was warmer than at present, reconstructions of cryospheric responses can serve as a potential analogue for future climate warming.