重庆秀山寒武纪海相碳酸盐的锶同位素组成及其地层学意义

STRONTIUM ISOTOPE COMPOSITION OF THE CAMBRIAN LUOJIAGUO SECTION IN XIUSHAN, CHONGQING AND ITS STRATIGRAPHIC SIGNIFICANCE

锶同位素地层学是化学地层学的组成部分 ,简要介绍重庆市秀山县溶溪乡罗家沟寒武系剖面海相碳酸盐的锶同位素分析结果 ,建立了该剖面的锶同位素演化曲线 ,并与 Gao及 Denison等的同期锶演化曲线作了对比 ,秀山寒武纪锶同位素演化曲线与其他两条同期曲线有较大相似性 ,据此提出了秀山寒武系剖面部分主要年代地层界线的参考意见 ,并简述了寒武纪全球海平面变化的概况。

The Sr-isotopic stratigraphy is a part of the chemostratigraphy. Its fundamental principle is introduced briefly in this paper. According to the analysis results of strontium isotope of marine carbonate samples collected from the Cambrian section in Xiushan, the Sr-isotope curve of this section is set up using the data with relatively low 87Sr/ 86Sr ratio is correlated with 2 coeval other curves set up by Denison et al. (1998) and Gao G et al. (1991). They are consistent. Some positions of key chronostratigraphic boundaries about the Xiushan section were suggested and the global variation of the sea level during the Cambrian period was discussed briefly.