中国东部寒武系与奥陶系界线地层的碳氧同位素研究

对我国东部不同地层区一些代表性的寒武系-奥陶系界线层位开展了碳?氧同位素研究?结果表明,由于沉积环境差异和成岩蚀变影响,界线层位的δ18O值变化较大,规律性不明显,δ13C值变化虽小,但在界线处均发生不同程度漂移?漂移的层位与寒武纪-奥陶纪主要生物群面貌变化的界线相一致?综合各方面资料分析,笔者认为,碳同位素组成的漂移很可能由晚寒武世到早奥陶世时期内海平面的升降所引起.

Carbon and Oxygen Isotopic Study across the Cambrian Ordovician Boundary Strata in East China

Carbon and Oxygen isotopic study of some representative Cambrian-Ordovician boundary strata ofvarious stratigraphic areas in East China has done.It was indicated that the variation of δ18,O values inboundary strata is larger and the regularity of variation is not conspicuous because of the difference ofsedimentary environment and the effect of diagenetic alteration.But the variation of δC values is smalland the various degree of excursion in the boundary strata occurs.The excursive stratohorizon is consis-tent with the variation boundary of major biotic population.According to the study of various data, it wasbelieved that the excurson of carbon isotopic compositions is likely attributed to the televation and subsi-dence of sea level from the Late Cambrian to Early Ordovician.