| Despite the small analytical error of 0.1 - 0.3 percent, the total uncertainty in Ar-40/Ar-39 dating is usually one order of magnitude larger due to the combined uncertainties in the decay constants and the age of the mineral dating standards. On the other hand, the completely independent absolute dating method of astronomical tuning is characterised by an extremely small total error which is in the order of 0.1 percent or even less for Neogene times, provided that the tuning itself is correct. Following the rigorous intercalibration of both dating methods (Kuiper, 2003) we propose to introduce a direct astronomically dated sanidine standard in order to reduce current uncertainties in Ar-40/Ar-39 dating by eliminating errors that result from uncertainties in the decay constants and in the age of mineral dating standards to a large extent. In addition we propose to carry out additional fusion experiments on sanidine crystals to demonstrate that xenocrystic contamination is indeed responsible for observed inconsistencies in the intercalibration. Further, we plan to extend our intercalibration to the U/Pb dating system as an independent check on our Ar-40/Ar-39 astronomical timescale intercalibration by U/Pb dating of zircons and/or titanite derived from ash layers that have previously been dated by the Ar-40/Ar-39 and astronomical methods. Finally, we intend to apply the new astronomical standard to dating magnetostratigraphically well constrained ash layers of Paleogene age as a critical independent check on the correctness of the astronomical tuning of this time interval. |
