The upper Cambrian of the Chopko River section, Norilsk region, Northwestern Siberian platform: Stratigraphy and trilobites

Варламов, А.И.; Pak, Karen; Rosova, A. V.

doi:10.1134/s0031030106030191

Cited by 10 publications

(13 citation statements)

References 8 publications

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“…Pseudagnostus rugosus closely resembles P. intermedius Varlamov, Pak & Rosova, 2005 from the Agnostotes clavatus-Irvingella perfecta, Norilagnostus quadratus-Irvingella cipita and Irvingella norilica zones in the Chopko River section, Norilsk District, northwestern Siberian Platform. Pseudagnostus intermedius differs, however, from P. rugosus in having a 30% wider anteroaxis, smaller pygidial spines, a more constricted glabella, a wider cephalic border furrow, and a less pronounced anteroglabella.…”

Section: Systematic Palaeontologymentioning

confidence: 85%

Pseudagnostus rugosusErgaliev, 1980: a key agnostoid species for intercontinental correlation of upper Furongian (Cambrian) strata

Terfelt

Ahlberg

2010

Geol. Mag.

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Pseudagnostus rugosusErgaliev, 1980 is described from the FurongianCtenopyge tumidaZone at Gislövshammar, Scania, southern Sweden. This is the first record of this distinctive agnostoid in Scandinavia. The species is known previously from Malyi Karatau, Kazakhstan, and northwestern Hunan and western Zhejiang, South China, and provides a newly recognized link between middle–upper Furongian successions in Baltica, Kazakhstan and South China. The occurrences ofP. rugosusallow a correlation between theC. tumidaZone of Baltica, the lowerEolotagnostus scrobicularis–JegorovaiaZone of Kazakhstan and the lowerLotagnostus americanusZone of South China.

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Section: Systematic Palaeontologymentioning

confidence: 85%

Pseudagnostus rugosusErgaliev, 1980: a key agnostoid species for intercontinental correlation of upper Furongian (Cambrian) strata

Terfelt

Ahlberg

2010

Geol. Mag.

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“…By contrast, the Middle-Upper Cambrian transitional strata of the Kulyumbe section were deposited on the carbonate platform, in inner shelf environments (Fig. 1), where almost all the trilobites are endemic (Rozova, 1963(Rozova, , 1964(Rozova, , 1984Rozanov et al 1992;Sukhov, 1997;Varlamov, Pak & Rozova, 2006). Therefore, biostratigraphic correlation between these two sections is difficult, and alternative methods, such as chemostratigraphy, are needed.…”

Section: The Middle-upper Cambrian Boundary In the Kulyumbe Sectionmentioning

confidence: 99%

“…2; Table 5 of Supplementary Material). The trilobites from the Kulyumbe section are endemic forms (Rozova, 1963(Rozova, , 1964(Rozova, , 1984Rozanov et al 1992;Sukhov, 1997;Varlamov, Pak & Rozova, 2006), and therefore their evolutionary pattern and diversity changes differ from those of forms with global distribution. Hence, the observed decline in diversity at Kulyumbe could be related to local palaeogeography and environments.…”

Section: The Middle-upper Cambrian Boundary In the Kulyumbe Sectionmentioning

confidence: 99%

The SPICE carbon isotope excursion in Siberia: a combined study of the upper Middle Cambrian–lowermost Ordovician Kulyumbe River section, northwestern Siberian Platform

et al. 2008

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-An integrated, high-resolution chemostratigraphic (C, O and Sr isotopes) and magnetostratigraphic study through the upper Middle Cambrian-lowermost Ordovician shallowmarine carbonates of the northwestern margin of the Siberian Platform is reported. The interval was analysed at the Kulyumbe section, which is exposed along the Kulyumbe River, an eastern tributary of the Enisej River. It comprises the upper Ust'-Brus, Labaz, Orakta, Kulyumbe, Ujgur and lower Iltyk formations and includes the Steptoean positive carbon isotopic excursion (SPICE) studied here in detail from upper Cambrian carbonates of the Siberian Platform for the first time. The peak of the excursion, showing δ 13 C positive values as high as +4.6 ‰ and least-altered 87 Sr/ 86 Sr ratios of 0.70909, is reported herein from the Yurakhian Horizon of the Kulyumbe Formation. The stratigraphic position of the SPICE excursion does not support traditional correlation of the boundary between the Orakta and Labaz formations at the Kulyumbe River with its supposedly equivalent level in Australia, Laurentia, South China and Kazakhstan, where the Glyptagnostus stolidotus and G. reticulatus biozones are known to immediately precede the SPICE excursion and span the Middle-Upper Cambrian boundary. The Cambrian-Ordovician boundary is probably situated in the middle Nyajan Horizon of the Iltyk Formation, in which carbon isotope values show a local maximum below a decrease in the upper part of the Nyajan Horizon, attributed herein to the Tremadocian Stage. A refined magnetic polarity sequence confirms that the geomagnetic reversal frequency was very high during Middle Cambrian times at 7-10 reversals per Ma, assuming a total duration of about 10 Ma and up to 100 magnetic intervals in the Middle Cambrian. By contrast, the sequence attributed herein to the Upper Cambrian on chemostratigraphic grounds contains only 10-11 magnetic intervals.

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“…Upward from Stage 5 agnostoids are among the principal biostratigraphical guides for the Cambrian (e.g. Westerg ard 1946Westerg ard , 1947Westerg ard , 1953Palmer 1962;€ Opik 1963€ Opik , 1966€ Opik , 1967€ Opik , 1979Shergold 1972Shergold , 1975Shergold , 1980Shergold , 1982Shergold , 1997Daily & Jago 1975;Henderson 1976Henderson , 1977Robison et al 1977;Rushton 1979Rushton , 2009Ergaliev 1980;Rowell et al 1982;Robison 1984Robison , 1994Ludvigsen & Westrop 1985;Shergold et al 1990;Peng 1992;Ahlberg & Ahlgren 1996;Pegel 2000;Ahlberg 2003;Peng et al 2004aPeng et al ,b, 2009bPeng et al 2012a,b;Babcock et al 2005Babcock et al , 2011Peng & Babcock 2005a,b, 2008Varlamov et al 2005;Axheimer et al 2006;Ahlberg et al 2007;Ergaliev & Ergaliev 2008;Dubinina 2009;Robison & Babcock 2011;…”

Section: Cambrian Biostratigraphymentioning

confidence: 99%

Cambrian trilobite biostratigraphy and its role in developing an integrated history of the Earth system

Babcock

Shanchi

Ahlberg

2017

LET

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One of the principal biostratigraphical tools used in the lower Palaeozoic, and especially the Cambrian System, is trilobites. Historically, both polymerids and agnostoids have commonly been included as ‘trilobite’ groups, although currently the question of whether they comprise a monophyletic group or are polyphyletic is unsettled. Beginning in the late 1800s, the base of the Cambrian System was marked by the lowest occurrence of olenelline trilobites. Discovery of a rich pre‐trilobite metazoan record in the mid‐1900s led to significant modification of that concept, but polymerids and especially agnostoids still rank among the leading biostratigraphical and chronostratigraphical guides through much of the Cambrian. Chronostratigraphical sub‐division of the trilobite‐bearing part of the Cambrian System derives largely from biostratigraphical, ecological and evolutionary concepts about agnostoids and polymerids introduced in the 1940s to 1970s by A.H. Westergård, A.R. Palmer and R.A. Robison. Westergård introduced a zonation for Scandinavia that was largely based on agnostoids. Palmer explained the distribution of Cambrian trilobite faunas in terms of restricted and unrestricted access to open oceans. Together, these ideas coalesced in Robison's recognition of separate zonation schemes for restricted‐shelf polymerids, open‐shelf polymerids and open‐shelf (cosmopolitan) agnostoids. Palmer also introduced the concept of biomeres, which placed sharp limits on biostratigraphical intervals recognizable from trilobites. Global correlation in the upper half of the Cambrian today depends to a large extent on the ranges of agnostoids and some polymerids characteristic of open‐shelf to slope areas, ones that facilitate identification of precise intercontinental tie points. Agnostoid and polymerid biostratigraphy is now being integrated with information about coastal onlap and eustatic sea‐level history, geochemical cycling and other data to provide a more complete understanding of the early Palaeozoic biosphere and its complex physico‐chemical context.

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The upper Cambrian of the Chopko River section, Norilsk region, Northwestern Siberian platform: Stratigraphy and trilobites

Cited by 10 publications

References 8 publications

Pseudagnostus rugosusErgaliev, 1980: a key agnostoid species for intercontinental correlation of upper Furongian (Cambrian) strata

Pseudagnostus rugosusErgaliev, 1980: a key agnostoid species for intercontinental correlation of upper Furongian (Cambrian) strata

The SPICE carbon isotope excursion in Siberia: a combined study of the upper Middle Cambrian–lowermost Ordovician Kulyumbe River section, northwestern Siberian Platform

Cambrian trilobite biostratigraphy and its role in developing an integrated history of the Earth system

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