This article was downloaded by: [Jin Peng] On: 12 June 2014, At: 08:59 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK GFF Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/sgff20 Comments on some important issues concerning the establishment of a GSSP for Cambrian Stage 5 Yuanlong Zhaoa, Jinliang Yuanb, Qingjun Guoc, Jin Penga, Leiming Yinb, Xinglian Yanga, Chunjiang Wangd & Haijing Suna a College of Resource and Environment Engineering of Guizhou University, Guiyang 550025, China; b Nanjing Institute of Geology and Palaeontology, The Chinese Academy of Sciences, Nanjing 210008, China c Institute of Geographic Sciences and Natural Resources Research, Center for Environmental Remediation, Chinese Academy of Sciences, Beijing 100101, China d State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China Published online: 28 Feb 2014. To cite this article: Yuanlong Zhao, Jinliang Yuan, Qingjun Guo, Jin Peng, Leiming Yin, Xinglian Yang, Chunjiang Wang & Haijing Sun (2014) Comments on some important issues concerning the establishment of a GSSP for Cambrian Stage 5, GFF, 136:1, 333-336, DOI: 10.1080/11035897.2014.884629 To link to this article: http://dx.doi.org/10.1080/11035897.2014.884629 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. 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Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions GFF, 2014 Vol. 136, No. 1, 333–336, http://dx.doi.org/10.1080/11035897.2014.884629 Note Comments on some important issues concerning the establishment of a GSSP for Cambrian Stage 5 YUANLONG ZHAO1, JINLIANG YUAN2, QINGJUN GUO3, JIN PENG1, LEIMING YIN2, XINGLIAN YANG1, CHUNJIANG WANG4 and HAIJING SUN1 Zhao, Y., Yuan, J., Guo, Q., Peng, J., Yin, L., Yang, X., Wang, C. & Sun, H., 2014: Comments on some important issues concerning the establishment of a GSSP for Cambrian Stage 5. GFF, Vol. 136 (Pt. 1, March), pp. 333–336. q Geologiska Fo¨reningen. doi: http://dx.doi.org/10.1080/11035897.2014.884629. Abstract: In order to help facilitate stratigraphic correlation between south China and Siberia, trilobite zones of Guizhou, China, and the Molodo River area, Siberia, need to be better coordinated. The Wuliu- Zengjiayan section is a strong candidate for the Global Standard Stratotype Section and Point for Cambrian Stage 5, and the Molodo River section provides important supplemental information that helps expand the precision of correlation on a global scale. The Kaili Formation in the Wuliu-Zengjiayan section contains three trilobite zones over an interval of 214.20 m. We propose that the Ovatoryctocara granulata Zone, as used in Siberia, replace the Ovatoryctocara Zone. Equivalent strata in Guizhou extend more than 150 m stratigraphically, from the Protoryctocephalus wuxunensis Zone to the Bathynotus kueichouensis–O. cf. O. granulata Assemblage Zone. We also propose that the traditional Kounamkites Zone be supplemented or replaced by the Oryctocephalus reticulatus Zone, which outside Siberia contains Oryctocephalus indicus. Keywords: Oryctocephalus indicus; Ovatoryctocara granulata; Cambrian Stage 5; GSSP; China; Siberia. 1College of Resource and Environment Engineering of Guizhou University, Guiyang 550025, China; [email protected] 2Nanjing Institute of Geology and Palaeontology, The Chinese Academy of Sciences, Nanjing 210008, China 3Institute of Geographic Sciences and Natural Resources Research, Center for Environmental Remediation, Chinese Academy of Sciences, Beijing 100101, China 4State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China Manuscript received 9 January 2014. Revised manuscript accepted 14 January 2014. Downloaded by [Jin Peng] at 08:59 12 June 2014 Introduction The first appearance datum (FAD) of Oryctocephalus indicus Some important factors or points of contention affecting the was originally proposed to mark the base of Cambrian Stage 5 decision about establishment of the GSSP for Stage 5 are and was accepted as a potential boundary horizon by the summarized as follows. International Subcommission on Cambrian Stratigraphy in 2005 (Babcock et al. 2005). More than 10 years have passed since the Working Group on Stage 5 was established (Geyer & Shergold Geographic distribution of potential FADs for 2000), and it has been 11 years since Fletcher (2003) first Stage 5 proposed the FAD of Ovatoryctocara granulata as another O. indicus was first described from the Himalayan region (Fig. 1, potential boundary marker of the Cambrian Stage 5. This No. 5) and has since been reported from Korea, south China (Fig. proposal was supported by Peng et al. (2006). Several field 1, Nos 1 and 2), Greenland (Fig. 1, No. 4), the United States (Fig. excursions have been organized to explore these and other 1, Nos 6 and 7) and Siberia (Fig. 1, No. 2; Zhao et al. 2012a). potential boundary levels, resulting in the delayed establishment Oryctocephalus reticulatus from Siberia can be distinguished of a GSSP for Cambrian Stage 5, as the issues regarding Stage 5 from O. indicus mainly by the undeveloped second and third pairs have been carefully considered by specialists. Two potential of transglabellar furrows (Shabanov et al. 2008). However, many boundary horizons and sections are the leading contenders under specimens of O. reticulatus from the Molodo River show poorly consideration: (1) the FAD O. indicus level in the Wuliu- developed second and third transglabellar furrows. The poorly Zengjiayan section, Guizhou, China and (2) the FAD developed transglabellar furrows may have resulted from Ovatoryctocara granulate level in the Molodo section, Siberia compaction in sediment, which opens the possibility that some (Yakutia), Russia. specimens of O. reticulatus could be reassigned to O. indicus.In 334 Zhao et al.: Comments on GSSP for Cambrian Stage 5 GFF 136 (2014) Fig. 1. O. indicus (Reed, 1910) from south China, Siberia, Greenland, Himalayan region of India and North America. (1) Dorsal exoskeleton, GTB- 26-1-211, Wuliu-Zengjiayan section of the Kaili Formation, Balang, Jianhe County, Guizhou, China; (2) cranidium, HS-72-3, from base of the Tianpeng Formation of Mengzi County, Yunnan Province (Luo et al. 2009); (3) dorsal exoskeleton, with distinct transglabellar furrows in cranidium, from the Kounamkites Zone of the Kuonamka Formation, Molodo River section Siberia, previously referred to O. reticulatus Lermontova, 1940 by Shabanov et al. (2008, pl. 11, fig. 1); (4) cranidium previously referred to O. cf. indicus by Geyer & Peel (2011, fig. 19,A, Downloaded by [Jin Peng] at 08:59 12 June 2014 MGUH 29403 from GGU collection 482335); (5) cranidium, from Himalaya of India (see Jell & Hughes 1997); (6 and 7) from the Plagiura Zone, California: (6) cranidium, internal mold, USNM 4108055; (7) internal mold of thorax with pygidium, USNM 488757 (see Sundberg & McCollum 1997, figs. 9-4, 10); scale bar is 1 mm, except for image 2, which is 2 mm. addition, the poorly preserved specimen assigned to Cheiruroides Tongren City (Zhao et al. 2012a). The species is also found at arcticus Tchernysheva, 1962 from the Oryctocara Zone the base of the Tianpeng Formation, which was deposited in a (Egorova et al. 1976, p. 97, pl. 43, fig. 14) has three pairs of shallow-water platform facies, in Mengzi County, Yunnan distinct transglabellar furrows, and it too could possibly be Province (Luo et al. 2009). reassigned to O. indicus. Some specialists have argued about whether O. reticulatus is a junior synonym of O. indicus (Korovnikov 2001, 2006; Zhao et al. 2001, 2007; Fletcher 2007; Candidate sections for the GSSP of Cambrian Yuan et al. 2011). However, we have found specimens in the Stage 5 Wuliu-Zengjiayan section of China that agree well with The Wuliu-Zengjiayan section through the Kaili Formation, in assignment to O. reticulatus (Zhao et al. 2012a), and for that Guizhou, China, is well exposed without significant tectonic or reason, we prefer to keep separate names for the two forms. metamorphic alteration. The section has been well studied, and Recently, some new localities yielding O. indicus have been more than 48 articles published about it (Zhao et al. 2012a). In recognized in south China. Most are in the Kaili