Local overprints on the global carbonate δ13C signal in Devonian-Carboniferous boundary successions of South China

An integrated study of the litho-, bio-, and chemostratigraphy of the Devonian-Carboniferous boundary at four sections (Qilinzhai, Malanbian, Gedongguan and Long'an) in South China was undertaken in order to better understand paleoenvironmental changes and controls on delta C-13(carb) variation during the Hangenberg Crisis. Sedimentological data record a major regression in the Middle Siphonodella praesukata Zone, which coincided with the Hangenberg Extinction (HE) in South China. Our new delta C-13(carb), data document a negative delta C-13(carb) shift near the base of the Middle S. praesulcata Zone, which may have been related to the HE. Prior to and during the HE, respiration of organic matter contributed abundant C-12-enriched dissolved inorganic carbon (DIC) to the restricted Nanning carbonate platform, resulting in a negative vertical delta C-13(DIC) gradient in the study area. In the Upper S. praesukata Zone, all four sections exhibit a positive delta C-13(carb) shift, suggesting that a vigorous biological pump existed in the aftermath of the latest Devonian glaciation. However, peak delta C-13(carb) values differ markedly among the study sections, suggesting that local carbon cycling processes played an important role during the initial post-glacial transgression. (C) 2014 Elsevier B.V. All rights reserved.