Multi-step post-IR IRSL dating and palaeoclimate implications from 270 to 90 ka in the Central Shandong Mountains, eastern China

Abstract

The aeolian sediments in the Central Shandong Mountains (CSM) in eastern China provide a faithful carrier of climate and sea-level variations outside of the Chinese Loess Plateau. However, due to the lack of or limited application of absolute dating protocols, previous studies of Shandong loess have focused mainly on loess deposited since the last interglacial period, with fewer studies on provenances and climate changes recorded in older penultimate interglacial period characterized by a long duration and significant climate fluctuations, which is not helpful to understand the spatiotemporal pattern changes of East Asian monsoon. In this study, multi-elevated-temperature post-infrared infrared-stimulated luminescence (MET-pIRIR) dating method was utilized to obtain the absolute ages from the Dongheishan (DHS) section in CSM region. Preheat plateau and dose recovery tests indicate that the MET-pIRIR signals of 250 °C and 300 °C have negligible anomalous fading and they can give reliable ages for the loess since ∼270 ka. Luminescence dating results suggest that the DHS loess mainly accumulated from 265 ± 12 ka to 93 ± 4 ka. The loess sedimentation rates during ∼195 ± 18–108 ± 4 ka were much lower than expected in the DHS section, which occurred approximately correlates with the Qingshui erosion period (∼136 ka), as indicated by the planation surface outside the CSM. Both the grain-size characteristics and sedimentation rate variations suggest that the dust sources of the DHS loess were primarily proximal sediments, which is possibly due to frequent variations in dust provenances caused by plentiful precipitation during the interglacial periods and diversions of the Yellow River. This study implies that the CSM loess with a good chronology could be utilized to decipher regional sedimentation and climatic changes processes.