Influence of Na-feldspar grains within the K-feldspar fraction on sediments IRSL dating

IF 1.9 3区地球科学 Q3 GEOGRAPHY, PHYSICAL

Quaternary International Pub Date : 2024-07-20 DOI:10.1016/j.quaint.2024.06.009

Dongxue Li , Hui Zhao , Haichao Xie , Farhad Khormali , Aijun Sun , Shuai Zhang

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引用次数: 0

Abstract

The post-Infrared Infrared Stimulated Luminescence (pIRIR) protocol has been successfully applied to date Quaternary sediments using the K-rich feldspar fraction (density ＜2.58 g/cm³). However, during the extraction of K-feldspar grains, Na-feldspar particles (density 2.58–2.62 g/cm³) may be included, especially within the medium grained fraction. However, the possible influence of Na-feldspar contamination on K-feldspar IRSL dating results has not been investigated in detail. In this study, we applied the pIRIR dating protocol to measure the coarse- and medium-grained K-and Na-feldspar fractions of eight aeolian samples from various regions. Blue-violet and yellow-green detection windows were used for derived the signals of K- and Na-feldspar, respectively, and we attempted to evaluate the influence of the contamination by Na-feldspar grains on feldspar pIRIR dating. Comparison of the three signals (K-feldspar blue, Na-feldspar blue, Na-feldspar yellow) from each sample showed that the influence of the IRSL blue signal from Na-feldspar grains on the signal of the K-feldspar fraction was < 1–3%. Because of high fading rates, the D_es or pIRIR ages obtained from the Na-feldspar yellow signal were underestimated. The Na-feldspar blue pIRIR D_es and ages were nevertheless consistent with their corresponding K-feldspar blue D_e values and ages. This is because the few K-feldspar grains included within the Na-feldspar fraction emitted the greater part of the blue signals. From these observations, we conclude that the influence of Na-feldspar grains within the K-feldspar fraction on K-feldspar IRSL dating results can be ignored.

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K长石部分中的钠长石颗粒对沉积物IRSL年代测定的影响

利用富含钾长石（密度＜2.58 g/cm3）的第四纪沉积物，后红外红外激发发光（pIRIR）方案已成功应用于确定其年代。不过，在提取钾长石颗粒的过程中，可能会包括钠长石颗粒（密度为 2.58-2.62 克/立方厘米），尤其是在中粒部分。然而，Na 长石污染对 K 长石 IRSL 测年结果可能产生的影响尚未得到详细研究。在本研究中，我们应用 pIRIR 测年方案测量了来自不同地区的八个风化样本中的粗粒和中粒 K 长石和钠长石部分。蓝紫色和黄绿色探测窗口分别用于推导钾长石和钠长石的信号，我们试图评估钠长石颗粒的污染对长石红外定年的影响。对每个样品的三个信号（K-长石蓝、Na-长石蓝、Na-长石黄）进行比较后发现，Na-长石颗粒的 IRSL 蓝色信号对 K-长石部分信号的影响为 < 1-3%。由于衰减率高，从钠长石黄色信号得到的 Des 或 pIRIR 年龄被低估了。不过，钠长石蓝色 pIR Des 值和年龄与相应的 K 长石蓝色 De 值和年龄是一致的。这是因为 Na 长石部分中的少数 K 长石晶粒发出了大部分蓝色信号。根据这些观察结果，我们得出结论，K长石部分中的钠长石晶粒对K长石IRSL年代测定结果的影响可以忽略不计。

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来源期刊

Quaternary International 地学-地球科学综合

CiteScore

5.60

自引率

4.50%

发文量

336

审稿时长

3 months

期刊介绍： Quaternary International is the official journal of the International Union for Quaternary Research. The objectives are to publish a high quality scientific journal under the auspices of the premier Quaternary association that reflects the interdisciplinary nature of INQUA and records recent advances in Quaternary science that appeal to a wide audience. This series will encompass all the full spectrum of the physical and natural sciences that are commonly employed in solving Quaternary problems. The policy is to publish peer refereed collected research papers from symposia, workshops and meetings sponsored by INQUA. In addition, other organizations may request publication of their collected works pertaining to the Quaternary.