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

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 Varmland, west central Sweden. Calendar year ages were obtained from varve counts and are supported by additional C-14 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 14 C age based on studies in the British Isles and Germany. Considering the age-error estimates associated with the varve chronology and calibrated C-14 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 C-14 years), between Hekla-3 and Hekla-4 to ca 1135 +/- 55 varve years (formally estimated to ca 1100 calibrated C-14 years) and between Hekla-3 and Kebister, 708 +/- 20 varve years. (C) 2002 Elsevier Science Ltd. All rights reserved.