南京附近下蜀黄土内腹足类化石的氨基酸外消旋年代测定

AMINO ACID RACEMIZATION DATING OF LATE PLEISTOCENE GASTROPOD SHELLS FROM SANSHANJI NEAR NANJING

一、引言自Bada, Wehmiller和Hare等首先使用氨基酸外消旋反应测定贝壳化石年龄以来,随着实验仪器和实验技术的改进,这一方法得到了较快发展和应用,为第四纪地质古生物的研究提供了新的途径。甚至还有可能为较老地层的划分对比及生态环境的研究提供证据。因此,氨基酸外消旋年龄测试技术逐渐受到人们的关注。自1979年Bada在中国科学院南京地质古生物研究所讲授“贝壳化石的氨基酸外消旋年龄测定”以后,刘德明等(1987)较成功地进行了福建沿海全新世贝壳沉积物的氨基酸外消旋年代测定。本文报道的是南京附近三山矶下蜀黄土内腹足类化石的氨基酸外消旋年代测定,以及氨基酸组份含量与其生态环境的关系。承唐天福教授审阅文稿并提出宝贵建议,臧晓泉绘制图表,笔者在此表示衷心感谢。二。

This paper deals with problems on amino acid racemization dating by means of D-alloisoleucine to L-isoleucine ratios and geochemical characters of amino acid shown by results from analysis on the total content of amino acids. The samples analysed were shells of Bradybaena rauida collected from the Pleistocene deposits at Sanshanji near Nanjing. The results indicate an evident increase in the D/L ratios with the deepening of deposits in the section. The alleu/iso ratio of 0.254 from the bottom of the section indicates an age of 18 468 yrs. While results from the determination on the total content of amino acids in the shell samples from the middle part of the section suggest a neutral by basic environment.