Revisiting the chronology of a key loess section in North America using multiple luminescence dating methods

Abstract

[eng] The Loveland paratype section contains valuable records of the climatic conditions during glacial and interglacial periods across the midcontinent of North America. Previous studies have focused on developing chronological data for the last glacial period, and only a few studies have reported ages for older loess units. Therefore, the aim of this study is to refine the chronological framework of the Loveland paratype section, especially for the deposition of Loveland Loess, using a combination of state-of-the-art luminescence methods. Three sets of optically stimulated luminescence (OSL) ages were obtained by applying single-aliquot regenerative (SAR) dose protocol on coarse (63−90 μm) quartz and two elevated temperature post-infrared infrared stimulated luminescence (pIRIR) protocols, namely pIRIR225 and pIRIR290, on polymineral fine grains extracted from seven samples. For the uppermost five samples collected from Pisgah Loess and upper Loveland Loess, we report coarse quartz SAR-OSL ages that range from 49 ± 4 ka to 146 ± 13 ka. For the older samples, only pIRIR ages were reported due to the saturation of luminescence signal from quartz. Except for the lowermost sample, the ages agree with those of previous studies reported for this loess section. However, for the oldest samples, which were collected from the bottom of the Loveland Loess, an age is reported that predates the Illinoian glaciation.