See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/270213769 The Khos-Nelege River section of the Ogon’or Formation: a potential candidate for the GSSP of Stage 10, Cambrian System Article in Bulletin of Geosciences · September 2011 DOI: 10.3140/bull.geosci.1270 CITATIONS READS 16 178 4 authors, including: Ivan Ya. Gogin T.V. Pegel A.P. Karpinsky Russian Geological Research Institute Siberian Research Institute of Geology, Geophysics and Mineral Resources, Russia… 6 PUBLICATIONS 66 CITATIONS 31 PUBLICATIONS 308 CITATIONS SEE PROFILE SEE PROFILE All content following this page was uploaded by T.V. Pegel on 04 May 2016. The user has requested enhancement of the downloaded file. The Khos-Nelege section of the Ogonor Formation: a potential candidate for the GSSP of Stage 10, Cambrian System NADEZHDA P. LAZARENKO, IVAN Y. GOGIN, TATYANA V. PEGEL &GALINA P. ABAIMOVA The International Subcommission on Cambrian Stratigraphy (ISCS) has recommended a subdivision of the Cambrian System into four series and ten stages. The first appearance datum (FAD) of the cosmopolitan agnostoid trilobite Lotagnostus americanus has been chosen as a good indicator for the base of the uppermost Cambrian stage (Stage 10). The Khos-Nelege section located in the north-eastern Siberian Platform (Western Yakutia, Russia) is proposed as the Global Standard Stratotype Section and Point (GSSP) for the base of the ‘Cambrian Stage 10’. The proposed GSSP coin- cides with the FAD of L. americanus at 339 m above the base of the Ogon’or Formation. The section fulfills the geologi- cal and biostratigraphical requirements for a stratotype and the GSSP horizon can be constrained by a number of auxil- iary marker taxa. The first appearance of L. americanus is an easily recognizable level in the Cambrian which can be recognized from all major Cambrian continents, including Baltica, Laurentia, Avalonia, South China and Australia. • Key word: Cambrian, Stage 10, trilobite, GSSP, Lotagnostus americanus, Russia. LAZARENKO, N.P., GOGIN, I.Y., PEGEL, T.V. & ABAIMOVA, G.P. 2011. The Khos-Nelege River section of the Ogon’or Formation: a potential candidate for the GSSP of Stage 10, Cambrian System. Bulletin of Geosciences 86(3), 555–568 (12 figures). Czech Geological Survey. Prague, ISSN 1214-1119. Manuscript received January 1, 2011; accepted in re- vised form July 6, 2011; published online September 19, 2011; issued September 30, 2011. Nadezhda P. Lazarenko, State Enterprise All-Russia Research Institute for Geology and Mineral Resources of the World Ocean, 1 Angliyskiy Prospect, St. Petersburg, 199121, Russia • Ivan Y. Gogin, Russian Geological Research Institute, 74 Sredny Prospect, St. Petersburg, 199106, Russia; [email protected] • Tatyana V. Pegel (corresponding author) & Galina P. Abaimova, Siberian Research Institute of Geology, Geophysics and Mineral Resources, 67 Krasny Pros- pect, Novosibirsk, 630091, Russia; [email protected], [email protected]; [email protected] Subdivision of the Cambrian System into series and stages are the Fortunian Stage (= base of Terreneuvian Series and that can be applicable in a global scale is among major ob- Cambrian System), the Drumian Stage, Guzhangian Stage jectives of the International Subcommission on Cambrian and the Paibian Stage (= base of Furongian Series). Apart Stratigraphy (ISCS) for a number of years. The absence of from the Paibian, the two succeeding stages (Cambrian internationally recognized global standard for the Cam- Stage 9 and 10) in the Furongian Series remain to be de- brian System partly a consequence of different stratigrap- fined. In addition, in 2010, Duibian B section in Zhejiang, hical approach developed historically by researches work- China was chosen by the ISCI as GSSP for the base of the ing in different regions, but also reflects faunal Cambrian Stage 9 (= Jiangshanian Stage) defined by the provincialism resulted the scarcity of suitable biostratig- FAD of the agnostoid trilobite Agnostotes orientalis. How- raphical markers applicable for intercontinental correlation ever, this decision is still awaiting ratification from the at the Stage level. However, current progress in research on Commission on Stratigraphy IUGS. Babcock et al. (2005) Cambrian trilobite biostratigraphy in combination with suggested that the FAD of the agnostoid trilobite chemostratigraphy improved significantly long-range cor- Lotagnostus americanus, may be the best choice for defin- relation of the regional Cambrian chronostratigraphic units ing the base of the Cambrian Stage 10, which is the only (Babcock et al. 2005). Furongian Stage remaind awaiting for formal designation The ISCS came to the conclusion that the Cambrian (Fig. 1). System subdivision into four series and ten stages, looks as The main objective of this paper is to present updated the most practical strategy (Babcock et al. 2005). So far, and refined documentation for a stratigraphic sequence only four stages have been formally named and formally through the upper part of the Furongian Series in the Khos- approved by the Commission on Stratigraphy IUGS. These Nelege section which is presented as a GSSP candidate for DOI 10.3140/bull.geosci.1270 555 Bulletin of Geosciences Vol. 86, 3, 2011 border furrow; and presence of posterolateral marginal spines. Based on these criteria, L. obscurus Palmer should be excluded from the synonymy of L. americanus, because it has a nonscrobiculate surface and a short pygidial axis with a rounded posterior termination. This suggests that Lotagnostus obscurus has the closest affinity to the subge- nus Lotagnostus (Eolotagnostus) Zhou. Lotagnostus americanus has a short stratigraphic range in the late Furongian and is a common taxon in the open shelf lithofacies (Peng & Babcock 2005 and references therein) (Fig. 2). Presently, occurrences of L. americanus are docu- mented from Quebec, Newfoundland, Precordilleran Ar- gentina, Sweden, China, Kazakhstan (Malyi Karatau), Kyrgyzstan (north Tien Shan), Australia, Avalonia (Eng- land and Wales), and Siberia (Babcock et al. 2005, Geyer & Shergold 2000, Peng & Babcock 2005, Peng et al. 2005) and it can be identified with precision using multiple lines of evidence. Lotagnostus americanus is widely used as the index taxon in Siberia, China and Scandinavia (Lazarenko et al. 2008, Peng & Babcock 2005, Terfelt et al. 2008). The early representatives of Lotagnostus emerged at the time, when Eurudagnostus and Oncagnostus (Oncagnostus) Figure 1. Chart showing working model for the global chrono- went into extinction or were in terminal decline, and the stratigraphical subdivision of the Cambrian System, indicating the posi- tion of the Cambrian Stage 10 and its lower boundary (modified from agnostoid genus Trilobagnostus had just appeared Babcock et al. 2005). (Ergaliev & Ergaliev 2008, Terfelt et al. 2011, Lazarenko et al. 2008). Lotagnostus (Lotagnostus) americanus occupied an in- designation of the Cambrian System ‘Tenth’ Stage, de- termediate position in the evolution of Lotagnostus. Species fined by the FAD of the agnostoid trilobite Lotagnostus of Lotagnostus (Eolotagnostus), which differ in having americanus. poorly scrobiculate cephalic pleurae (sometimes pygidial pleurae too) and a rounded posterior termination of a rela- tively short pygidial axis, appeared earlier in the sequence Motivation for selection of the boundary than the first representatives of Lotagnostus (Lotagnostus) level and of the potential stratotype section and Lotagnostus (Distagnostus). For instance in China Lo- tagnostus (Eolotagnostus) occurs at the Furrongian Lotag- Lotagnostus (Lotagnostus) americanus (Billings) is easily nostus (Eolotagnostus) decorus-Kaolishaniella Biozone recognizable agnostoid taxon, which was recently revised and Probilacunaspis nasalis-Peichiashania chunanensis by Peng & Babcock (2005). It was demonstrated that a Biozone (Peng 1992), whereas in Kazakhstan (Malyi number of species, including Lotagnostus asiaticus Troeds- Karatau) it is documented from the Lotagnostus son, L. xinjiangensis Zhang, L. punctatus Lu, L. trisectus (Eolotagnostus) scrobicularis-Jegorovaia Biozone (upper (Salter), L. obscurus Palmer and Goniagnostus verrucosus Aksayan Regional Stage) (Ergaliev & Ergaliev 2008). Rusconi represent junior objective synonyms of Lotagnos- The evolutionary lineage of the genus Lotagnostus ter- tus americanus, thus presently this trilobite species is do- minated with L. hedini, which is the index-species of a cumented from almost all major Cambrian paleoconti- biozone designated for the uppermost Furongian in China nents, which makes it a valuable tool for global correlation. (West Zheijang, Peng 1992) and in Kazakhstan (upper part The diagnostic characteristics of Lotagnostus of Batyrbaian Regional Stage of Malyi and Bolshoi Kara- americanus include: lengthwise partition of the axis into tau ranges) (Ergaliev & Ergaliev 2008). In the Batyrbai three parts; pleurae with distinct scrobiculae; cephalon section of the Malyi Karatau Range, Kazakhstan, Lotag- with a narrow roll-shaped border; a pentagonal anterior nostus hedini occurs in the upper part of the Proconodontus glabellar lobe; F3 curved backwards; node on the main notchpeakensis conodont zone (Apollonov & Chugaeva glabellar lobe occupying the most elevated part of the 1983). In the Dadoushen section, Duibian, China, cephalon; elongated basal lobes; presence of a preglabellar Lotagnostus hedini occurs together with the conodonts furrow; a long pygidial axis; medially effaced