Calendar year ages of three mid-Holocene tephra layers identified in varved lake sediments in west central Sweden

Abstract

Three intermediate to rhyolitic Icelandic Holocene tephra horizons (Hekla-3, Kebister, and Hekla-4) have been identified in annually laminated (varved) lake sediments in the Province of Värmland, west central Sweden. Calendar year ages were obtained from varve counts and are supported by additional 14C dating based on terrestrial plant macrofossils. The varve ages of the three tephras are 3295±95 cal. BP (Hekla-3), 4030±103 cal. BP (Kebister), and 4390±107 cal. BP (Hekla-4). The varve age of Hekla-3 refines the former calibrated 14C age based on studies in the British Isles and Germany. Considering the age-error estimates associated with the varve chronology and calibrated 14C ages, the ages of Kebister and Hekla-4 are in agreement with former studies. Thus, the age difference between Kebister and Hekla-4 is estimated to be ca 400±40 varve years (formally estimated to ca 200 14C years), between Hekla-3 and Hekla-4 to ca 1135±55 varve years (formally estimated to ca 1100 calibrated 14C years) and between Hekla-3 and Kebister, 708±20 varve years.