沉积物ESR测年及在川西-滇北河流阶地定年中的应用

ESR能够直接测定第四纪碎屑沉积物年代，尤其是对老于距今20万年以上的沉积物而被广泛应用，但其不很高的测年精度及可重复性不高又限制了其应用的广泛性。野外样品采集及室内分析测试的各个环节都会对ESR测年精度产生影响，因此控制这些环节造成的各种误差是提高ESR测年精度的关键。川西-滇北地区部分河流阶地沉积物ESR年代测定结果与地层层序以及区域地质构造事件基本吻合，表明ESR法测定该区河流阶地沉积物的年代是可行的。在野外采样以及实验室内样品处理测试过程中，采取合理的措施，可以把ESR测年的误差控制在10％～15％的范围内，基本能够满足研究的需要。

ESR DATING OF SEDIMENTS AND ITS APPLICATION IN AGE DETERMINATION OF THE RIVER TERRACES IN WESTERN SICHUAN AND NORTHERN YUNNAN, CHINA

The Quaternary sediments, especially the debris deposits older than 200 ka, can be dated by ESR. However, its poor precision and reproducibility limited its application. The errors can be produced during sampling, carrying and measurement in lab. Therefore, it is important for rising precision to control the produc- tion of these errors. The result of ESR dating in terraces sediments on the Western Sichuan and Northern Yunnan Plateau basically tally with sequence of stratigraphy and tectonic events, indicating its reliability in terrace dating. According to our experience, the ESR dating error would be limited to 10% - 15%, if we do some proper treatments during the process of sample collecting in the field and sample pretreatment and measurement in the lab.