中国科学院南京地质古生物研究所机构知识库

We report new delta C-13 chemostratigraphic data of the Ediacaran System in South China. Using litho- and biostratigraphic markers as independent calibrators, we combine new and previously published delta C-13 data to construct a composite delta C-13 profile for the Ediacaran System in South China. The composite curve shows, in chronostratigraphic order, 1) a negative 613 C excursion (EN 1) in the Doushantuo cap carbonate that overlies the Ghaub-age Nantuo diamictite; 2) a pronounced positive delta C-13 excursion (EP 1) in the lower Doushantuo Formation where Doushantuo-type acanthomorphic acritarchs, red algae, and animal embryos first appear; 3) a mild negative delta C-13 excursion (EN2) in the middle Doushantuo Formation; 4) a positive delta C-13 excursion (EP2) in the upper Doushantuo Formation where Doushantuo-type acanthomorphic acritarchs, micrometazoans, and stem group florideophyte red algae become abundant and diverse; 5) a pronounced negative delta C-13 excursion (EN3) near the uppermost Doushantuo Formation; 6) a strongly positive delta C-13 excursion (up to +6.3(parts per thousand) PDB; EP3) in the lower Dengying Formation; 7) a stable delta C-13 plateau (ca. + 2.5 parts per thousand PDB; EI) in the middle and upper Dengying Formation where abundant vendotaenid algae, macroscopic Ediacamn fossils, biomineralized animal tubes, and mostly horizontal animal traces occur; and 8) a -10 parts per thousand negative delta C-13 excursion (EN4) immediately below the Ediacaran-Cambrian boundary. The general pattern of this composite delta C-13 curve is robust, despite a considerable amount of variation among the 613C profiles of different sections. This composite delta C-13 curve provides a first-order chemostratigraphic framework for the subdivision and correlation of the Ediacaran System in South China. (c) 2006 Elsevier B.V. All rights reserved.