In addition to dating, IRSL luminescence signals can preserve information about erosional, transport, and depositional histories of a population of grains. Knowledge of the degree of bleaching can be useful in understanding the processes that occurred during previous depositional events, as certain transport conditions result in a well bleached signal, while others result in grains retaining an inherited signal from prior events. This information can be accessed by making single-grain IRSL measurements across successively increasing temperatures, thereby isolating signals from traps of different bleachabilities.

A new approach offers a way to evaluate the completeness of bleaching of a grain by testing patterns of equivalent dose (D_E) values measured at three elevated temperatures (3ET), 50, 125, and 225 °C. Consistent D_E estimates across two or more temperatures suggest a single bleaching event of sufficient duration to fully depopulate the traps involved. Incompletely bleached grains with inconsistent D_E values across temperatures will lack a 3ET “plateau.” Modes in the distribution of D_E values for fully bleached grains can suggest depositional ages, subject to assessment of fading. We developed a Python code in a Jupyter Notebook environment for data analysis and visualization to expedite processing the large data sets produced by the 3ET protocol.

The 3ET protocol was tested on a radiocarbon dated sequence of playa samples from California, USA and on a set of fluvial terraces in the Marlborough region of New Zealand as part of a larger project to reconstruct regional seismic history. Where standard pIRIR apparent ages can be inconsistent or ambiguous, 3ET age estimates produce generally consistent apparent ages. Modes of 3ET plateaus can be used to infer the most recent and prior events that resulted in a sub-population of grains being fully bleached. These initial results suggest that the 3ET method can be useful to characterize both the age and degree of bleaching of depositional events.

除了测年，IRSL 发光信号还可以保存有关晶粒群的侵蚀、迁移和沉积历史的信息。漂白程度的知识有助于理解在先前沉积事件中发生的过程，因为某些传输条件会产生良好的漂白信号，而其他条件会导致晶粒保留先前事件的遗传信号。可以通过在连续升高的温度下进行单粒 IRSL 测量来获取此信息，从而将信号与不同漂白能力的陷阱隔离开来。

一种新方法提供了一种通过测试在三个高温 (3ET)、50、125 和 225 °C 下测量的等效剂量 (D _E ) 值模式来评估谷物漂白完整性的方法。在两个或多个温度下一致的 D _E估计表明，一次漂白事件的持续时间足以完全消除所涉及的陷阱。_{不同温度下 D E}值不一致的未完全漂白谷物将缺乏 3ET“平台”。D _{E分布模式}完全漂白的晶粒的值可以表明沉积年龄，但需要对褪色进行评估。我们在 Jupyter Notebook 环境中开发了 Python 代码，用于数据分析和可视化，以加快处理 3ET 协议生成的大型数据集。

作为重建区域地震历史的更大项目的一部分，3ET 协议在来自美国加利福尼亚的普拉亚样品的放射性碳年代序列和新西兰马尔堡地区的一组河流阶地上进行了测试。在标准 pIRIR 表观年龄可能不一致或模棱两可的情况下，3ET 年龄估计会产生大致一致的表观年龄。3ET 高原模式可用于推断导致谷物亚群完全漂白的最近和先前事件。这些初步结果表明，3ET 方法可用于表征沉积事件的年龄和漂白程度。