Isotopic Evidence for the Temperature Change of the Paleo-Ocean between Late Devonian Fransnian Period and Famennian Period in South China
晚泥盆世弗拉斯期—法门期之交海水温度变化的同位素证据

The shallow platform sedimentary facies is well-developed along the Laojiangchong section in Xikuangshan mine,Lengshuijiang area,Hunan Province,which includes the well-known Upper Devonian Fransian-Famennian(Fr/Fa) boundary.Long period of field studies and researches led the authors to reveal the palaeotnology as well as sedimentary associations and characteristics.The shells of brachiopod Cyrospirifer vernemili were analysed isotopically and by SEM in this study.The carbon and oxygen isotopic analyses (δ18O:-8.4‰～-9.6‰; δ13C: -2.2‰～0.5‰) show an abnormal shift around the boundary of Fr/Fa in South China,which can serve as a standard of regional tratigraphic correlation.Depending on the calculation of oxygen isotopes within the well preserved brachiopods,the authors drew the inference about temperature decreasing from late Fransian to early Famennian.