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目前的研究显示,欧、美等大陆晚泥盆世地层中普遍存在碳同位素δ13C的正偏移,这种偏移已被推测为全球海洋有机碳埋藏速率快速增加的结果,并与晚泥盆世弗拉阶(Frasnian)-法门阶(Famennian)之交发生的生物集群灭绝事件(简称F-F事件)密切相关.华南上泥盆统是研究F-F事件理想地层之一,其中是否存在δ13C正偏移,直接关系到全球范围内是否存在与F-F事件有关的有机碳埋藏增强的问题.对广西桂林垌村具有生物地层控制的晚泥盆世剖面进行了高分辨率的碳酸盐稳定同位素分析,结果表明;δ13C在F-F转换时期总体呈逐步增加趋势,这种趋势由两次明显的δ13C正偏移组成:第1次正偏移出现在linguiformis带的底界,δ13C增加幅度达1.5‰;第2次正偏移出现在triangularis/linguiformis带(F-F)的界线,增幅达2.1‰.与世界其他地区的同位素记录对比发现,在生物地层时限上,垌村剖面第1次出现的δ13C正偏移较晚,而发生在F-F界线的第2次正偏移,无论在生物地层上还是在变化幅度上都是基本一致的,支持F-F时期全球性的有机碳埋藏增强的观点.
The current research shows that the δ13C carbon isotope is widely distributed in the Late Devonian strata in continental Europe, the United States and other continents. This shift has been presumed to be the result of the rapid increase of burial rate of marine organic carbon in the world and is associated with the late Devonian The extinction event (FF event) is closely related to the Frasnian - Famennian extinction event (FF event). The Upper Devonian in South China is one of the ideal stratigraphy to study the FF event, in which is there a δ13C positive offset Is directly related to whether there is a global increase in the burial of organic carbon associated with the FF event.A high-resolution carbonate stable isotope analysis was performed on the Late Devonian section with biostratigraphy control in Guilin, Guangxi Province. Results The results show that δ13C tends to increase gradually during the period of FF conversion. This trend consists of two obvious δ13C positive deviations: the first positive excursion appears at the bottom of the linguiformis zone, and the δ13C increases by 1.5 ‰. The second The subnormal migration appears at the boundary of triangularis / linguiformis zone (FF), with an increase of 2.1 ‰. Comparing with the isotopic records of other parts of the world, it is found that the δ13 C positive offset later, and the second positive offset in the F-F boundary is basically the same both in the biostratigraphy and in the change range, supporting the view that the global carbon burial in the F-F period is enhanced.