High Resolution Quartz OSL and K-feldspar post-IR IRSL Dating of Loess in the Central Shandong Mountains (Eastern China)

Abstract

The loess sediments widely distributed in the Central Shandong Mountains are sensitive records of East Asian monsoon changes for situating in a key region connected to the Eurasian Plate and the Pacific Ocean. However, the detailed processes of palaeoclimatic changes are poorly understood for the lack of high-resolution chronology. In this study, the chronology of Heishan loess palaeosol sequence in the Central Shandong Mountains is investigated using quartz SAR OSL and K-feldspar post-IR infrared (IR) stimulated luminescence (post-IR IRSL) dating method. The quartz is sensitive, fast component dominated and saturate at ∼150 Gy (∼50 ka). The measured K-feldspar pIRIR<sub>290</sub> D<sub>e</sub> showed no dependency on the first IR stimulation temperature between 50°C and 260°C. The K-feldspar pIRIR<sub>290</sub> ages are consistent with the stratigraphy up to ∼75 ka. In establishing the chronological sequence for the study section, quartz OSL ages <50 ka and the K-feldspar pIRIR<sub>290</sub> ages >50 ka were selected. Derived sedimentation rates show two relatively rapid stages of ∼32.0 ± 5.5 cm/ka for the palaeosol (∼11–8 ka) and ∼54.8 ± 1.1 cm/ka for the loess (∼34–30 ka). An erosional hiatus of loess between ∼30 ka and ∼17 ka is identified. We conclude that the pIRIR<sub>290</sub> of loess sediments is applicable for samples during ∼8–75 ka.