HOLOCENE AEOLIAN SEDIMENTATION AND EPISODIC MASS-WASTING EVENTS RECORDED IN LACUSTRINE SEDIMENTS ON LANGøYA IN VESTERåLEN, NORTHERN NORWAY

Abstract In this study, the frequency of mass-wasting events and past storminess has been reconstructed throughout the Holocene (11,500 cal yr BP to present) from lacustrine sediments in lake Trehynnvatnet (33 m a.s.l.), which is located in a glacially carved valley at Nykvag on the outmost coast of western Langoya, Vesteralen, northern Norway. Sediment cores (∼2–5 m long) have been examined by use of high-resolution magnetic susceptibility and XRF-scanning as well as grain size and loss-on-ignition analysis. In total 35 episodic event layers have been identified throughout the Holocene. The majority of these events are characterized as discrete coarse-grained sediment layers followed by normal grading, and are related to past mass-wasting activity within the catchment. Periods with high mass-wasting activity are dated to 11,000–10,500, 5500–4500, 4000–3500, 3000–2500, 2000–1000 and 500–0 cal yr BP. The continuous input of sand grains (>250 μm) has been systematically investigated throughout the sediment cores. The sand grains are related to catchment samples from the sandy beach deposits in Sandvikbukta c. 750 m away in SW direction, and are suggested to indicate (niveo-) aeolian influx to the lake. The content of sand grains varies greatly throughout the record, although there is a clear increase in influx of sand during the last 2800 years. Periods with high aeolian influx are proposed to indicate increased storminess, which occurred between 1600 and 1550 (350–400 CE), 1400–1300 (450–550 CE), 750–550 (1200–1400 CE) and 250–20 cal yr BP (1700–1930 CE), which to some degree coincides with periods of increased storminess and winter precipitation recorded in other studies around the North Eastern Atlantic region.