Proglacial lake records of Holocene glacier behaviour and catchment processes in Slettedalen, Northeast Greenland

Abstract

Constraining Arctic catchment response to Holocene climate change is vital for understanding future environments. We present detailed sedimentological, geochemical and grain size end-member analysis of two Holocene (~7.0 ka to present) lake sequences, S1 and S2, close to Zackenberg, Northeast Greenland. They provide new insights into glacier behaviour and catchment processes during a period of profound environmental change. The lowermost unit (>6.8 ka) captures the retreat of Dombjerg glacier and exposure of the S1 and S2 basins—unified by high water levels—when they received large volumes of glacigenic sediment. During the Holocene Thermal Maximum (~6.8–3.5 ka), Dombjerg glacier receded. High runoff, slope processes and fluvial activity dominated. S1 and S2 became largely disconnected, forming two depocentres; S1 was characterised by glacial and glaciofluvial inputs and S2 was characterised by alluvium and colluvium. Dombjerg glacier advanced during Neoglacial cooling (after ~2.0 ka). S1 and S2 were again unified by higher lake levels, facilitating the throughflow of glacigenic material into both depocentres. The LIA is poorly expressed or absent in the Slettedalen records, commensurate with regional reconstructions. At present, the basins are connected only by streamflow, and coarse-grained sediment reflects renewed runoff and slope instability under ongoing climate warming.