石英ESR测年信号衰退特征研究进展

电子自旋共振(ESR)测年法是第四纪地质年代学的重要测试方法之一,其测年范围广,特别是对于20万年至百万年尺度的第四纪样品有着重要意义.准确测量古剂量是影响ESR测年法精度和可信度的重要因素之一,而掌握ESR信号衰退特征及机制是获得准确、可信古剂量的重要前提.ESR测年法适用的地质样品种类较多,如热液石英脉、地质断层泥、水系沉积物等,不同样品的ESR信号衰退特征和机制有较大差异.近年来,国内外学者针对不同地质样品中石英ESR信号的衰退特征和机制深入开展了一系列的实验室模拟和野外观测研究,取得了诸多新认识.回顾了近年来在石英ESR信号衰退特征领域取得的进展,特别是水系沉积物石英ESR信号的衰退特征,并展望了这一领域的未来工作重点.

Research Progress of the Resetting Features of Quartz ESR Signal

Electron Spin Resonance (ESR) has been becoming one of the key methods of Quaternary Geochronology with wide range of dating, especially for sample older than 200,000 years up to million year scale. ESR dating assesses the age of a sample by measuring the equivalent dose and annual dose. The accurate measurement of equivalent dose significantly impacts on accuracy and reliability of ESR dating method. Under ideal conditions, any previous acquired ESR intensity is reset to zero or a stable residual level that can be determined in the laboratory. Therefore, the study of the mechanisms of resetting processes is fundamental for accurate and reliable ESR dating. Since ESR dating method is applicable to the type of geological samples, including hydrothermal quartz veins, geological fault gouge and fluvial sediment, there are large differences in the mechanisms and characteristics of ESR signal resetting. In recent years, to understand the mechanism and characteristics of quartz ESR signal resetting of different geological samples, a series of laboratory simulation and field observation studies were carried out, which made lots of important breakthrough. In this paper, we summarize progress in ESR dating of quartz in Quaternary sediments and studies of resetting mechanisms with particular emphasis on fluvial sediments and prospects for future work.