黔西滇东地区二叠纪-三叠纪过渡层中叶肢介化石研究

The correlation between the marine and terrestrial Permian-Triassic (P-Tr) strata has a great significance for the definition of the terrestrial P-Tr boundary and the comprehensive understanding for the nature of this global biotic and environmental event, as well as the key and difficult question for the international paleotology and stratigraphy. Here, we try to establish the biostratigraphic correlation framework between the marine and terrestrial P-Tr depositions, based on the well geological records of a gradual change from terrestrial to marine facies via the terrestrial-marine siliciclastic facies in the adjoining area between western Guizhou and eastern Yunnan (WGEY). This study focuses on the taxonomy, evolutionary lineage and stratigraphy of P-Tr transitional conchostracans (clam shrimps, spinicaudatans) in the terrestrial and terrestrial-marine siliciclastic facies in WGEY, which were regarded as a intermediate link for biostratigraphic correlation between terrestrial and marine sequences. Meanwhile, the methods of the physiology and ecology for the modern conchostracans were employed to investigate the biology characteristic and adaptive mechanisms of P-Tr transitional conchostracan fossils. This may demonstrate the scientific rationality and general application of the conchostracans that being the biological mark for the P-Tr terrestrial stratigraphic division and correlation.

二叠纪-三叠纪之交海、陆相地层对比研究对陆相二叠系-三叠系界线的定义以及全面认识该全球性重大生物与环境突变事件具有重要意义，也是当前国际古生物学与地层学研究的重点和难点。为此，本项目选择叶肢介化石为研究对象，依托我国黔西滇东地区二叠纪-三叠纪之交良好的陆相和海-陆过渡相地层记录，通过对该地区二叠纪-三叠纪过渡层中叶肢介化石的分类学、演化特征和地层学的研究，揭示该地区二叠纪-三叠纪之交叶肢介化石的时空分布特征，并以海陆过渡相地层为“桥梁”，建立二叠纪-三叠纪过渡期叶肢介生物地层与海相生物地层的对比关系。另外，通过与现生叶肢介进行类比分析，从生理学和生态学的角度分析该时期叶肢介化石的生物学属性和广域性适应机制，从而论证叶肢介化石可以作为该时期地层划分和对比标志的科学合理性和应用广泛性。

根据项目设计工作部署，对黔西滇东地区二叠纪-三叠纪过渡层中的叶肢介化石进行了分类学和古生态学研究，建立了叶肢介化石的生物地层序列和跨区域的对比关系，进而在相同的时间框架下对研究区二叠纪-三叠纪之交的生物与环境事件进行了深入剖析，取得了一定的科学进展和创新性认识，达到了项目设计目标。项目实施以来，围绕设计主题共发表标注论文5篇，其中SCI期刊论文4篇，国内EI论文1篇。其重要的科学进展包括：.在叶肢介化石方面，对黔西滇东地区二叠纪-三叠纪之交的叶肢介化石进行分类学、生物地层学和演化研究，论证了叶肢介化石Euestheria gutta可以作为指示陆相二叠纪-三叠纪过渡层的标准化石，并且与同层位产出的化石相结合进行跨区域的地层对比，搭建了跨区域和夸相区的生物地层对比格架。在生物事件方面，通过叶肢介化石、植物化石和双壳类化石等进行生物地层划分和对比的基础上，精细刻画了黔西滇东地区陆相和海陆过渡相二叠纪-三叠纪之交灭绝事件的具体型式和过程，限定了了黔西滇东地区陆相灭绝事件发生的具体层位和时间，并对灭绝原因进行了探讨。