A Carnian Ar-40/Ar-39 age for the Paasselka impact structure (SE Finland)-An update

作者：Schwarz Winfried H^*; Schmieder Martin; Buchner Elmar; Trieloff Mario; Moilanen Jarmo; Ohman Teemu

来源：Meteoritics & Planetary Science, 2015, 50(1): 135-140.

DOI：10.1111/maps.12407

A recrystallized band of pale feldspathic impact melt in a gneissic impact breccia from the approximately 10 km Paasselka impact structure in southeast Finland was dated via Ar-40/Ar-39 step-heating. The newly obtained plateau age of 228.7 +/- 1.8 (2.2) Ma (2 sigma) (MSWD = 0.32; p = 0.93) is equal to the previously published pseudoplateau age of 228.7 +/- 3.0 (3.4) (2 sigma) for the impact event. According to the current international chronostratigraphic chart and using the most recent published suggestions for the K decay constants, a Carnian (Late Triassic) age for the Paasselka impact structure of 231.0 +/- 1.8 (2.2) Ma (2 sigma) is calculated and considered the most precise and accurate age for this impact structure. The new plateau age for Paasselk confirms the previous dating result but is, based on its internal statistics, much more compelling.

• 出版日期2015-1