Single-grain optical dating of Quaternary sediments: why aliquot size matters in luminescence dating
Single-grain optical dating of Quaternary sediments: why aliquot size matters in luminescence dating
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DOI：
10.1111/j.1502-3885.2008.00051.x
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发表时间：
2008-01-01
期刊：
影响因子：
2.2
通讯作者：
Duller, Geoffrey A. T.
中科院分区：
文献类型：
--
作者：
Duller, Geoffrey A. T.
光学测年法测量矿物颗粒暴露在日光下的时间。该技术是理想的沉积物中，所有的颗粒都暴露在足够的日光沉积重置光激发光（OSL）信号。然而，在许多环境中，单个颗粒暴露于日光的程度是可变的。有限的光照导致谷物保留了一部分先前捕获的电荷，如果不考虑这一点，就会导致高估年龄。在过去的15年中，控制用于每次发光测量的颗粒数量已经变得可行，从数千到单个颗粒不等。在同时测量许多颗粒的情况下，发光信号被平均化，并且颗粒之间的重置的任何可变性将被掩盖。本文介绍了单颗粒光释光测量的方法，并综述了该方法在第四纪冰川、河流和风成沉积物中的应用。单颗粒光释光通过明确评估样品在沉积时是否漂白，扩大了可以测年的环境范围，并提高了年龄的可靠性。
Optical dating measures the time that has elapsed since mineral grains were exposed to daylight. The technique is ideal for sediments in which all the grains were exposed to sufficient daylight at deposition to reset the optically stimulated luminescence (OSL) signal. However, in many environments the exposure of individual grains to daylight will be variable. Limited exposure to light results in grains retaining a part of any prior trapped charge, and if unaccounted for this causes overestimation of the age. In the past 15 years it has become feasible to control the number of grains used for each luminescence measurement, varying from many thousands to a single grain. Where many grains are measured simultaneously, the luminescence signal is averaged, and any variability in resetting between grains will be obscured. This article describes the methods involved in single-grain OSL measurements and review the application of the method to glacial, fluvial and aeolian Quaternary sediments. Single-grain OSL is expanding the range of environments that can be dated and improving the reliability of ages by explicitly assessing whether samples were bleached at deposition or not.