关键词: 腕足动物, 壳体保存状态, 碳, 氧同位素, 弗拉/法门界线, 华南

Abstract: Two basic shell structures are recognized based on study of brachiopods across the Frasnian-Famennian (F/F) boundary (Upper Devonian) in Hunan Province, South China, which are characterized respectively by the presence and absence of a tertiary columnar layer. For excluding poorly preserved shells, a shell alteration index is suggested to estimate the state of preservation of brachiopod shells through examination under cathodoluminescence and scanning electron microscopes. This study shows brachiopod taxa (e.g., Atrypida) with both secondary and tertiary layers have better state of shell preservation and more concentrate carbon and oxygen isotopic distribution than those only with secondary layers and consequently, are more reliable material to determine stable isotopic composition of the Devonian seawater.

Key words: brachiopods, preservation state, carbon and oxygen isotopes, Frasnian-Famennian, South China