Journal of Earth Science, Vol. 21, Special Issue, p. 70–74, June 2010 ISSN 1674-487X Printed in China Carbon Isotope Development in the Ordovician of the Yangtze Gorges Region (South China) and Its Implication for Stratigraphic Correlation and Paleoenvironmental Change Zhang Yuandong* (张元动), Cheng Junfeng (成俊峰) State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China Axel Munnecke GeoZentrum Nordbayern, University Erlangen-Nuremberg, Germany Zhou Chuanming (周传明) State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China INTRODUCTION The Ordovician was a critical period in the earth’s history. It was rather different in many respects from today (see review in Servais et al., 2010). For example, a greenhouse climate state with high carbon dioxide levels of 8–18 times present atmospheric level was probably a prevailing character of this period (Berner, 2001). In recent years, stable carbon isotope values have been widely used for the stratigraphic di- vision and correlation of Ordovician rocks (e.g. Bergström et al., 2008), as well as in paleoenviron- mental studies (Bergström et al., 2006). A composite carbon isotope curve through the Ordovician was pre- sented by Shields and Veizer (2004) and later by This study was supported by the Chinese Academy of Sciences (No. KZCX2-YW-122), the Ministry of Science and Technol- ogy (Nos. 2006CB806402, 2006FY1203000-4), and the Na- tional Natural Science Foundation of China (No. 40532009). *Corresponding author: ydzhang@nigpas.ac.cn © China University of Geosciences and Springer-Verlag Berlin Heidelberg 2010 Manuscript received December 22, 2009. Manuscript accepted January 10, 2010. Bergström et al. (2008), which shows a spectacular shift from negative δ 13 C values in the Early Ordovi- cian to mostly positive values in the Late Ordovician. On a global scale, several prominent short-lived posi- tive δ 13 C excursions have been recognized so far: (a) the mid Darriwilian excursion (Ainsaar et al., 2007), (b) the early Katian GICE (Guttenberg carbon isotope excursion or Chatfieldian excursion; Young et al., 2008, 2005; Saltzman and Young, 2005; Ainsaar et al., 1999), and (c) the HICE (Hirnantian carbon isotope excursion; Fan et al., 2009; Bergström et al., 2006; Young et al., 2005). The GICE excursion, coincident with a regressive event in central Nevada, was inter- preted by Saltzman and Young (2005) to be related with a global, but small-scale cooling event in early Katian, and was regarded by Bergström et al. (2009) as a consistent chemostratigraphic feature for the cor- relation of early Katian rocks. The HICE positive ex- cursion was globally recognized and widely regarded as being closely related with the Hirnantian glaciation and mass extinction. The carbon isotope development for the remaining interval of the Ordovician is com- paratively less well-known, partially due to the poor development of carbonates in many regions and con- tinents including North America, Baltica and Austral-