Reconstruction of Holocene patterns of change in a High Arctic coastal landscape, Southern Sassenfjorden, Svalbard

•Svalbard coastal systems responded abruptly to LGM glacier retreat.•Four marine terraces at Fredheim are a result of isostatic uplift during the Holocene.•MT4-3 were developed during the HTM, and MT2-1 during Neoglaciation.•Marine terraces are thought to have formed during predominantly calm periods.•Sea-ice-kettles on MT1-2 were produced by the icefoot/ push-ice during cooler times.

Abrupt shifts in sediment supply, relative sea level, permafrost regime, glacier state, snow cover and sea ice conditions associated with Holocene climate changes control processes operating on High Arctic coasts and make reconstructions of their past evolution a significant research challenge. This study attempts to describe the development of the coastal zone in southern Sassenfjorden, Svalbard, throughout the Holocene focusing on the styles of adjustment to major landscape changes. Five marine terraces (MT1-5) are identified and assessed. Spatial and chronological analysis suggests that the highest terrace, MT5, is pre-LGM (Last Glacial Maximum) and that MT4-3 underwent rapid uplift (151 and 11.4 mm/year, respectively) shortly prior to 11 061 ± 174 cal. yr BP and became fully terrestrial by 9100 years ago (as indicated by emergence rates) during the Holocene Thermal Maximum (HTM). Uplift rates for MT2-1 slowed to 5 and 2 mm/year, respectively, with suggested emergence between 7200 and 6800 cal. yr BP. A final 2 m uplift of the relict alluvial plain probably happened during the Medieval Warm Period (1200-950 cal. yr BP). Most recent coastal development (AD 1912-2012) is characterised by episodes of coastal erosion on the cliff and progradation of the Nøiselva delta. Interactions between sea ice, snow cover, permafrost, wind and wave regimes are assessed to understand their implications on future coastal development in a warming climate.