黄龙钙华210Pb计年与现代沉积的环境变化研究

本文以黄龙钙华岩芯为主要研究对象, 利用210Pb定年技术在测定年轻碳酸盐样品短时间尺度上的优势建立了研究区近100年来高精度的年代标尺及环境记录; 通过碳氧稳定同位素的分析, 讨论了钙华稳定同位素记录与器测气候数据的相关性特征, 并与其他定年技术所获得的结果进行了相互验证。研究区钙华δ18O在1908~2004年时段内的变化范围为?12.13‰~?10.42‰, 平均值为?11.23‰, 变化幅度达到了1.7‰。同属西南季风区、由于海拔效应和距离水汽来源远近不同等因素的影响, 在同时段内黄龙钙华δ18O的变化范围和变化幅度都比董歌洞和Kahf Defore洞的δ18O记录要大, 说明处于中纬度、高海拔的黄龙钙华相对于低海拔的董歌洞和Kahf Defore洞石笋对气候环境的响应可能更加敏感。

A Study of 210Pb Dating and Climatic Changes of Modern Sediments from Tufa in Huanglong, Sichuan Province

With the tufa core as the study object, the authors have reconstructed the high precision chronology and environmental records for the past one hundred years in Huanglong area using the 210Pb dating technique, which is effective for young carbonate samples and short time scale records. Based on an analysis of carbon and oxygen isotope data from the tufa core, this paper discusses the relationship between stable environmental isotopes and climatic data obtained by instruments with a comparison with other paleo-climatic records obtained by differentdating techniques. The δ18O values changed from -12.13‰ to -10.42‰ during 1908-2004, with the average being -11.23‰ and the variation range being 1.7‰. A comparison of δ18O values with Dongge Cave and Kahf Defore Cave in the same southwest monsoonal climate area and in the same study period shows that the δ18O values of the tufa core in Huanglong is higher than those of Cave records, probably attributed to the altitude effects and different distances from moisture source areas. It can be concluded that the tufa core records of Huanglong in the high altitude and middle latitude areas are more sensitive to climatic environmental changes than records of stalagmites in Dongge Cave and Kahf Defore Cave from low altitude areas.