Single-grain optical dating of sediment samples from Marathousa 1, Southern Greece

Abstract

Previous optical dating of sediment samples from Marathousa-1 used a multi-aliquot multi-grain procedure for feldspar mineral grains to obtain the equivalent dose (Jacobs et al., 2018). This was the best procedure available at the time for measurement of feldspar grains close to the upper limit of the technique (Li et al., 2017). A range of statistically consistent, but imprecise, age estimates were reported for 8 samples from two excavation areas at Marathousa 1 that suggested deposition of the clastic sediment package between lignite seams II and III during MIS 12 (478–424 ka; Lisiecki & Raymo, 2005). A measurement procedure for individual grains of feldspar has since been developed (e.g., Jacobs et al., 2019) as well as a procedure for direct measurement of the internal potassium content of individual grains (O’Gorman et al., 2021). Here, we present the updated multi-grain aliquot ages using a revised internal beta dose rate as well as single-grain age estimates for the same set of samples. The single grain De distributions suggest that the feldspar mineral grains in the lacustrine facies are well-bleached and that the age estimates are reliable.