A negative carbon isotope excursion defines the boundary from Cambrian Series 2 to Cambrian Series 3 on the Yangtze Platform, South China

A globally recorded negative carbon isotope excursion characterizes the transition from Cambrian Series 2 to Cambrian Series 3. This transition is also well exposed in sedimentary successions on the Yangtze Platform, and the Wuliu-Zengjiayan section, Guizhou Province, South China has been proposed as a potential Global Stratotype Section and Point (GSSP) for this boundary. Here, we report delta(13)C(carb) values for the Jianshan and the Wuliu-Zengjiayan sections. Both sections display a progressive decrease in delta(13)C from values around +3 parts per thousand upwards in stratigraphy to a pronounced delta(13)C minimum with values as low as - 6.9 parts per thousand at the proposed boundary level, and a return to delta(13)C values between 0 and + 1 parts per thousand in the upper part of the sections. The delta(13)C minimum is thought to be caused by a transgressive event, flooding the shelf area with (13)C depleted basinal anoxic bottom water. Our delta(13)C data are in good agreement with carbon isotope profiles recorded elsewhere. These define the so called ROECE event (Redlichiid-Oleneliid Extinction Carbon Isotope Excursion, cf. Zhu et al.. 2006,2007) and may reflect the perturbation of the global carbon cycle during the Cambrian Series 2 to Cambrian Series 3 transition. (C) 2009 Elsevier B.V. All rights reserved.