Postglacial relative sea level change and glacier activity in the early and late Holocene: Wahlenbergfjorden, Nordaustlandet, Svalbard

We obtained sediment cores from Kløverbladvatna, a threshold lake in innermost Wahlenbergfjorden, Nordaustlandet, Svalbard to reconstruct Holocene glacier fluctuations. Glacial meltwater from Etonbreen spills over a threshold to the lake, only when the glacier is considerably expanded compared to its present size. Lithological logging, loss-on-ignition, ITRAX scanning and radiocarbon dating of the cores show that Kløverbladvatna became isolated from the fjord c. 5.4 cal. kyr BP due to glacioisostatic rebound. During the remaining part of the Holocene, the lake experienced accumulation of laminated clayey gyttja from lacustrine organic production and surface runoff from the catchment. The Holocene sedimentary record suggests that meltwater only spilled over the threshold at the peak of the surge of Etonbreen in AD 1938. Hence, we suggest that this was the largest extent of Etonbreen in the (mid-late) Holocene. In Palanderbukta, a tributary fjord to Wahlenbergfjorden, a series of raised beaches was surveyed and organic material collected to determine the age of the beaches and reconstruct the postglacial relative sea level change. The age of the postglacial raised beaches range from 10.7 cal. kyr BP at 50 m a.s.l. to 3.13 cal. kyr BP at 2 m a.s.l. We mapped the postglacial marine limit at 65 m a.s.l., and extrapolation suggests that it formed c. 11.3 cal. kyr BP. The reconstructed postglacial relative sea level curve adds valuable spatial and chronological data to the relative sea level record of Nordaustlandet.