Intensified Late-Holocene aeolian activity in Vesterålen, northern Norway – increased storminess or human impact?

Abstract

This study reconstructs Mid- to Late-Holocene aeolian activity based on lacustrine sediments from a small pond, Nøkktjønna, situated ~1.5 km northeast from the coast, and stratigraphical investigations of coastal dunes at Fjærvoll, Langøya in Vesterålen, northern Norway. Several methods have been used to reconstruct catchment processes from the lacustrine record, including analyses of lithostratigraphy, organic content, magnetic susceptibility, and grain size, combined with high-resolution X-ray fluorescence (XRF) and Computed Tomography (CT) scanning. The content of coarse mineral grains (>125 μm) has been quantified throughout the lacustrine core by manual wet sieving and by conducting threshold analysis from the high-resolution CT-scans. Considering the setting of the drainage basin of Nøkktjønna, the mineral grains (>125 μm) in the sediment core are suggested to have been deposited by aeolian transportation from the nearby aeolian dunes and beach sand during storm events. Five periods of intensified aeolian influx (defined here as influx values above the 90th percentile) are identified. These periods occurred around ~6950, ~6500, ~6100–6000, 5800–5750 and ~350–20 cal. yr BP cal. yr BP, with the last period being the most intense. The increased influx in aeolian sand to Nøkktjønna is suggested to be associated with a combination of changes in the storm track pattern, sea-level fluctuations, conditions of snow cover/frozen surface and increased anthropogenic influence. The highest influx rates are recorded between CE 1600 and 1930, corresponding to the ‘Little Ice Age’ (LIA), which is a well-known period of high storminess in the North Atlantic region.