摘要
未经蚀变的海相碳酸盐岩的碳、锶同位素组成代表了原始海水的同位素组成。在确定样品末经显著蚀变的基础上,本文测定了上扬子地区晚古生代7条剖面238个海相碳酸盐岩样品的碳、锶同位素组成,公布了它们的测试结果和演化曲线,为其他相关研究提供了可利用的基础参照数据。曲线的演化趋势与前人公布的世界其他地方同时代的同位素演化趋势一致,显示出海相碳酸盐岩同位素组成的全球性对比意义。海平面变化、海底扩张速度、火山活动、生物绝灭更替、有机碳相对埋藏速度等全球地质事件是其主要控制因素。
The isotopic compositions of carbon and strontium of marine carbonate rocks which have not been altered by diagenesis represent the original marine water. 238 marine carbonate samples collected from the entire Late Paleozoic sedimentary succession in the upper Yangtze platform have been determined to be free from observable diagenestic diagenesis using the analysis of cathodolu-minescence and contents of Fe and Mn. Based on this work the author has precisely determined the compositions of carbon and strontium isotopes of the samples and set up the curves of S13C and 87Sr/86Sr versus geological time though the Late Paleozoic. The variation trend of the curves is quite consistent with that of the contemporaneous curves set up by the samples from North America . Europe, Africa and Asia, showing the global correlation significance of isotopic compositions of carbon and strontium of marine carbonate. The cruve of strontium exibits three intervals with lower ratios of 87Sr/86Sr, that is the Givetian and Frasnian of the Devonian, Early Carboniferous , and Early Permian, corresponding to the stages of the global high sea level. The decrease of 87Sr/86Sr ratio in the Late Permian resulted from the basalt eruption in the Yangtze platform. There are three intervals of increase of S13C throughout the Late Palaeozoic, which are the Givetian and Frasnian of the Devonian, Carboniferous, and Permian, representing a relatively high rate of accumulation of organic carbon. The sea-level rise was responsible for the increase of δ13C during the Givetian and Frasnian of the Devonian, Early Carboniferous, and Early Permian, and the deposition of coal was the cause for the increase of δ13C in other times. The δ13C values drop remarkably near the boundaries of the Devonian/Carboniferous, Carboniferous/Permian and Permian/Triassic, implying mass extinction and rejuvenation.
出处
《地质学报》
EI
CAS
CSCD
北大核心
1997年第1期45-53,共9页
Acta Geologica Sinica
基金
国家自然科学基金(编号 48970116)
关键词
上扬子台地
碳
锶
同位素
碳酸盐岩
upper Yangtze platform, Late Palaeozoic, marine carbonate, carbon and strontium isotopes
