宇生核素深度剖面暴露测年的原理与应用

宇生核素暴露测年技术是目前第四纪地貌年代测定最常用的方法之一，由于难以定量化继承性核素以及侵蚀对样品暴露年代的影响(通常假设继承性和侵蚀的影响为0),其测年结果难以反映地貌的真实暴露年代。通过测定地貌剖面不同深度样品的宇生核素浓度，建立“宇生核素浓度—深度”剖面曲线，可同时定量化研究地貌体的暴露年龄、继承性宇生核素浓度以及侵蚀速率，有效地弥补了宇生核素暴露测年中继承性核素以及侵蚀速率不确定性的缺陷。基于蒙特卡洛方法的宇生核素深度剖面暴露测年模型(简称蒙特卡洛深度剖面模型)是最常用的计算模式之一，然而，国内关于该方法的原理及其应用研究相对较少，大大限制了该方法的广泛使用。笔者等详细阐述了蒙特卡洛深度剖面模型的原理及其在冰川地貌、河流阶地、冲洪积扇等地貌测年中的应用。此外，介绍了深度剖面模型的复现、非稳态模型、线性反演模型等其他几种计算模式并进一步探讨了蒙特卡洛深度剖面模型暴露测年技术的野外采样方法，以使其能够广泛应用于第四纪地貌学和年代学研究中。

Introduction to cosmogenic nuclides exposure dating of depth profile

Terrestrial in situ cosmogenic nuclides(TCN) exposure dating method is one of the most used methods for Quaternary geomorphological dating research, but due to the influence of inherited nuclides and erosion, the dating results are difficult to reflect the real exposure age of the landform. Using the cosmogenic nuclide concentration of samples at different depths can comprehensively determine the exposure age, erosion rate and inherited nuclides of the geomorphology at the same time, effectively compensating for this shortcoming. The cosmogenic nuclide depth profile model based on the Monte Carlo method (referred to as the Monte Carlo depth profile model) is one of the most used models, and there are few domestic studies, which greatly limits the wide application of this method. This review will explain the principle of Monte Carlo depth profile model and its application in various landforms such as glacial landforms, river terraces, alluvial fans, etc., and introduce several other calculation modes such as the rejuvenation of depth profile model, unsteady state model and linear inversion model. This article will also discuss the field sampling method of depth profile dating technology, in order to be widely used in Quaternary geomorphology and chronology research.