40Ar/39Ar age calibration against counted annuallayers

• Main Authors: Storey, Michael, Stecher, Ole
• Format: Conference Object
• Language: English
• Published: 2008
• Subjects: Greenland; Greenland ice core; ice core; North Atlantic
• Online Access: https://forskning.ruc.dk/da/publications/77a03a00-dcba-11dd-87fb-000ea68e967b; https://hdl.handle.net/1800/77a03a00-dcba-11dd-87fb-000ea68e967b; http://www.cosis.net/abstracts/EGU2008/03535/EGU2008-A-03535.pdf

The 40Ar/39Ar method, based on the decay of the naturally occurring radioactive isotope 40K, is capable of producing ages with precision better than ± 0.1 %. However, accuracy is limited to no better than 1 % mainly due to the relatively large uncertainty in the 40K decay constants. One approach worth exploring for an improved absolute age basis for the 40Ar/39Ar system is through cross-calibration with counted annual layers (e.g. tree rings, varves and ice cores). North Atlantic Ash Zone (NAAZ) II is found within the dated part of the annual Greenland ice core record. NAAZ II has been correlated to the Icelandic peralkaline rhyolitic Thorsmörk ignimbrite. We will present preliminary 40Ar/39Ar results on the age of this eruption The 40Ar/39Ar method, based on the decay of the naturally occurring radioactive isotope 40K, is capable of producing ages with precision better than ± 0.1 %. However, accuracy is limited to no better than 1 % mainly due to the relatively large uncertainty in the 40K decay constants. One approach worth exploring for an improved absolute age basis for the 40Ar/39Ar system is through cross-calibration with counted annual layers (e.g. tree rings, varves and ice cores). North Atlantic Ash Zone (NAAZ) II is found within the dated part of the annual Greenland ice core record. NAAZ II has been correlated to the Icelandic peralkaline rhyolitic Thorsmörk ignimbrite. We will present preliminary 40Ar/39Ar results on the age of this eruption