ESR dating of the quaternary deep-sea sediment core RC17-177

Abstract

The deep-sea sediment core RC17-177 from the west equatorial Pacific was dated with ESR using the signal at g = 2.0036 of foraminifera. The measured dose rate parameters were: U-, Th- and K-concentrations, 234U- 230Th- and 231Pa-excess (initial values were assumed to be constant), average water content (derived from carbonate content) and a k α -factor of 0.1 ± 0.02 (own experiment). The ESR-signal growth curves on γ-irradiation have been fitted by single exponential saturation functions. However, significant deviations from a single exponential form have been observed for larger γ-doses. Agreement between ESR ages from the signal at g = 2.0036 and those from an independent δ 18O stratigraphy was observed up to 800 ka. The existence of outliers could be explained by variable initial Th-excess or water content at different depths. On the contrary, the signal at g = 2.0006 delivered ADs (and corresponding ages) that are far too small due to a low thermal stability.