巢湖地区早三叠世碳氧同位素地层对比及其古生态环境意义

CARBON AND OXYGEN ISOTOPIC STRATIGRAPHIC CORRELATION AND ITS PALEOENVIRONMENT SIGNIFICANCE DURING THE LOWER TRIASSIC, CHAOHU, ANHUI PROVINCE,CHINA

二叠纪—三叠纪之交的环境恶化事件不但导致了生物大绝灭,而且造成了自然界正常的碳循环崩溃。为了研究三叠纪早期生物复苏过程中的环境特征、碳氧同位素演化上的地层学意义,对巢湖平顶山西坡剖面下三叠统碳酸盐岩取样分析。研究结果表明,巢湖平顶山西坡剖面早三叠世碳氧同位素地层曲线与已知的平顶山北坡剖面碳氧同位素地层曲线相似。δ13C值在Induan阶、Olenekian阶底部首先表现为大幅度负漂,随后呈上升趋势。δ18O值除了表现出1Ma的周期性波动之外,与δ13C低值区对应处也具负偏趋势。δ13C、δ18O值的演化趋势反映了早三叠世海洋环境恶化、生物复苏十分缓慢。

Environmental deterioration events across the PermianTriassic boundary not only led to mass extinction, but also made natural carbon cycle collapse In order to investigate paleoenvironment characteristics and the stratigraphic significance of carbon and oxygen isotopes during the recovery in the Early Triassic, 114 carbonate samples for carbon and oxygen isotopic analysis were collected from the West Pingdingshan section, Chaohu, Anhui Province Results of carbon analysis showed that the carbon and oxygen isotopic stratigraphic profile of the Lower Triassic through the West Pingdingshan section is similar to that of the North Pingdingshan section, which was investigated previously Carbon isotopic curves display pronounced negative excursions, followed by slow increase during the early stages of Induan and Olenekian Oxygen isotopic values not only show a cyclic period of 1Ma during the Induan stage and the early stage of Olenekian, but also exhibit slightly negative shift within the regions where the carbon isotopic values display pronounced negative excursions Carbon and oxygen isotopic patterns indicate that the recovery was very slow in the severe environment in the Early Triassic after mass extinction at the PermianTriassic boundary