罗明^1,2,,
龚志军^1,,,
刘进峰²,
彭花明¹,
罗佳宏²,
毛宁凤¹
1. 东华理工大学地球科学学院, 江西 南昌 330013
2. 中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029

基金项目: 国家自然科学基金项目(批准号: 42062013)、教育部地震灾害科学研究与科学普及项目(批准号: G20200002)、江西省教育厅科学技术研究资助项目(批准号: GJJ160573)和东华理工大学核资源与环境国家重点实验室开放基金项目(批准号: NRE1607和2020Z01)共同资助


详细信息

作者简介: 罗明, 男, 31岁, 讲师/博士, 活动构造与释光年代学研究, E-mail: luoming@ecut.edu.cn

通讯作者: 龚志军, E-mail: 13697082584@163.com

中图分类号: P597

收稿日期:2020-12-28
修回日期:2021-06-25
刊出日期:2021-11-30

A novel approach for obtaining the actual erosion rate with rock surface luminescence dating

LUO Ming^1,2,,
GONG Zhijun^1,,,
LIU Jinfeng²,
PENG Huaming¹,
LUO Jiahong²,
MAO Ningfeng¹
1. School of Earth Sciences, East China University of Technology, Nanchang 330013, Jiangxi
2. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029


More Information

Corresponding author: GONG Zhijun,E-mail:13697082584@163.com

MSC: P597

--> Received Date: 28 December 2020
Revised Date: 25 June 2021
Publish Date: 30 November 2021


摘要
摘要:近年来新提出的岩石表层光释光测年技术为研究基岩在十年-万年时间尺度上的侵蚀速率提供了一种可能。该方法基本原理是暴露于太阳光下的岩石表层光释光信号会被逐渐晒退，其信号晒退的深度与岩石暴露时间以及岩石的侵蚀速率相关。因此，利用岩石表层残留光释光信号与信号深度、暴露时间以及侵蚀速率的定量关系，可以推算出该岩石的暴露年龄或者侵蚀速率。虽然前人已通过理论公式推导，为获取漂砾或基岩的稳态侵蚀速率提供了一种途径，但是该途径获得的稳态侵蚀速率为岩石的最大可达侵蚀速率，不一定是实际侵蚀速率。本次研究对前人的方法提出了两项优化和改进：第一，在岩石表层光释光测年技术中，对半饱和深度的误差提出了一种量化方式，而半饱和深度误差的量化为进一步比较不同岩石的光释光信号晒退程度提供了便利；第二，通过将样品的半饱和深度、误差和宇宙成因核素¹⁰Be年龄投影到不同侵蚀速率下半饱和深度与时间的关系模拟图中，进而获得样品的实际侵蚀速率。因此，优化后的方法可以有效地避免侵蚀速率的高估，为获得岩石十年-万年时间尺度上的实际侵蚀速率提供了一种新的可行途径。
关键词: 侵蚀速率/
光释光/
岩石表层/
暴露测年

Abstract:The application of rock surface luminescence dating in estimating erosion rate has attracted great attention. But there are still some quantitative problems to be solved. In this study, we attempt to optimize and improve the previous methods with a case study of data reprocessing of the Pamir glacier boulder sample in reference [13].
The depth of half saturation (L_n/T_n=0.5) of the luminescence depth profile could be treated as a measure for the bleaching depth. The errors can be estimated by reading the horizontal width of the 95% confidence intervals at L_n/T_n=0.5. Then, the bleaching depth and error of the residual luminescence-depth profiles of the Pamir samples are 15.3±0.2 mm and 14.4±0.2 mm. Based on the theoretical formula derivation, the formula of reference [13] is improved and further deduced. The relationship among the depths of half saturation, exposure time and erosion rates can be simulated through the improved formula. While the depths of half saturation at extreme ages(controlled by ¹⁰Be) of the sample are projected to the depths of half saturation-time profiles, the simulated profiles closest to the extreme values contain the actual erosion rates. The actual erosion rates obtained from the above method of the samples are 0.1~0.4 mm/ka and 0.3~0.7 mm/ka, which are indeed lower than the steady erosion rates correspondingly. Therefore, the method introduced in this study could effectively avoid overestimation of erosion rate of the rock.
Key words:erosion rate/
OSL/
rock surface/
exposure dating



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