广西柳桥深水相二叠系/三叠系界线剖面有机碳同位素地层学对比研究及事件响应

研究了广西柳桥地区东攀剖面有机碳同位素的组成,并和浙江煤山剖面进行了对比。结果表明东攀剖面在1δ3Corg变化趋势上,既具有全球PTB剖面普遍存在的共性,又具有其独特性。在东攀剖面一个显著的1δ3Corg负漂移出现在事件界线(EB)之上和二叠系/三叠系界线(PTB)之下,这与煤山剖面具有相似性。显著的1δ3Corg负漂移指示了P/T之交生物绝灭后海水表层水原始生产率的降低以及大气和海水中CO2含量的增加,并得到放射虫绝灭事件、火山事件和海退事件的响应。煤山剖面1δ3Corg负漂移从第27层就开始向13C富集的方向恢复,而东攀剖面1δ3Corg在下Induan阶仍持续亏损,表明东攀剖面早三叠世的生物复苏明显滞后于煤山剖面的。

Stratigraphy of Organic Carbon Isotope and Associated Events across the Permian/Triassic Boundary in the Dongpan Deep-Water Section in Liuqiao Area, Guangxi, South China

The organic carbon isotope compositions were examined for the first time from a well-preserved deep-water PTB section(Dongpan section) in Liuqiao area,Guangxi.The global correlation comparison is carried out by(organic) carbon isotope stratigraphy between Dongpan section and GSSP at Meishan section in Zhejiang.There are remarkable similarities and differences between the δ~(13)C_(org) trends of both sections.In Dongpan(section),a(remarkable) negative excursion occurs after the onset of 'PTB events',which is similar to Meishan section,and was accompanied by the mass extinction of radiolarian,volcanic activities and sea level fall.The recovery(towards) more enriched δ~(13)C_(org) values at Meishan section occurs in a zone of bed 27,but continued(negative)(δ~(13)C_(org)) values throughout the lower Induan in Dongpan section coincide with the marked recovery lag,which is probably related to continuously adverse conditions in the Early Triassic.