OSL dating of a Holocene loess-paleosol sequence in the southern Loess Plateau,China |
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| Authors: | Yaofeng Jia Chunchang Huang Longjiang Mao |
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| Institution: | (1) School of Management, North University for Nationalities, Yinchuan, 750021, China;(2) College of Tourism and Environment, Shaanxi Normal University, Xi’an, 710062, China;(3) College of Atmospheric Science, Nanjing University of Information Science and Technology, Nanjing, 210044, China |
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| Abstract: | Optically stimulated luminescence (OSL) dating of polymineral fine-grained loess samples collected from the southern Loess
Plateau of China was conducted using the single-aliquot regenerative-dose (SAR) protocol. A ‘Double-SAR’ procedure in which
aliquots are subjected to both infrared (IR) and blue stimulations was used, and two sets of equivalent dose (D
e
) determinations were produced. These doses are assumed to be predominantly related to the feldspathic and quartz fine grain
populations, respectively. The results revealed that the OSL ages estimated by infrared stimulated luminescence (IRSL) signals
and those estimated by post-IR] stimulated luminescence (post-IR] OSL) signals disagreed. Specifically, the ages estimated
using the IRSL signals were smaller than those estimated using post-IR] OSL signals. The results of an anomalous fading test
of the two types of OSL signals revealed that the post-IR] OSL signals from the etched sub-sample (by H2SiF6 and HF) and the un-etched sub-sample did not fade significantly. However, the IRSL signals from the un-etched sub-sample
showed obvious signs of fading. These findings indicate that the lower age estimated by IRSL is due to the anomalous fading
of feldspar IR signals in the polymineral fine grains. For samples collected from greater than 100 cm, the estimates of their
OSL ages using two types of luminescence signals generally agreed with their pre-estimated ages, especially those of the post-IR]
OSL signals. However, for the three samples that were collected from a depth of less than 100 cm, their OSL ages were remarkably
underestimated, possibly due to the enhanced human activity (such as soil cultivation) that has occurred in the region since
3000 a B.P. |
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