Carbon isotope record of Late Cambrian to Early Ordovician carbonates of the Argentine Precordillera

Buggisch, Werner; Keller, Martín; Lehnert, Oliver

doi:10.1016/s0031-0182(03)00365-1

Cited by 142 publications

(137 citation statements)

References 35 publications

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“…The re- Buggisch et al (2003) and Kaljo et al (2007). The numerical age estimates and chronostratigraphic divisions follow the global scheme after Gradstein et al (2004) and Bergström et al (2009).…”

Section: Methodsmentioning

confidence: 99%

High-resolution isotope stratigraphy of the Lower Ordovician St. George Group of western Newfoundland, Canada: implications for global correlation

Azmy

Lavoie

2009

Can. J. Earth Sci.

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Abstract:The Lower Ordovician St. George Group of western Newfoundland consists mainly of shallow-marine-platform carbonates (*500 m thick). It is formed, from bottom to top, of the Watts Bight, Boat Harbour, Catoche, and Aguathuna formations. The top boundary of the group is marked by the regional St. George Unconformity. Outcrops and a few cores from western Newfoundland were sampled at high resolution and the extracted micritic materials were investigated for their petrographic and geochemical criteria to evaluate their degree of preservation. The d 13 C and d 18 O values of wellpreserved micrite microsamples range from -4.2% to 0% (VPDB) and from -11.3% to -2.9% (VPDB), respectively. The d 13 Ccarb profile of the St. George Group carbonates reveals several negative shifts, which vary between *2% and 3% and are generally associated with unconformities-disconformities or thin shale interbeds, thus reflecting the effect of or link with significant sea-level changes. The St. George Unconformity is associated with a negative d 13 Ccarb shift (*2%) on the profile and correlated with major lowstand (around the end of Arenig) on the local sea-level reconstruction and also on those from the Baltic region and central Australia, thus suggesting that the St. George Group Unconformity might have likely had an eustatic component that contributed to the development-enhancement of the paleomargin. Other similar d 13 C carb shifts have been recorded on the St. George profile, but it is hard to evaluate their global extension due to the low resolution of the documented global Lower Ordovician (Tremadoc -middle Arenig) d 13 C carb profile.Résumé : Le Groupe de St. George (Ordovicien inférieur) de l'ouest de Terre-Neuve comprend surtout des carbonates de plate-forme marine peu profonde (épaisseur *500 m). De la base au sommet, il comprend les formations suivantes : Watts Bight, Boat Harbour, Catoche et Aguathuna. La limite supérieure du groupe est marquée par la discordance régionale de St. George. Des affleurements et quelques carottes provenant de l'ouest de Terre-Neuve ont été échantillonnés à haute rés-olution et les roches micritiques extraites ont été étudiées pour leurs critères pétrographiques et géochimiques afin d'évaluer leur degré de préservation. Les valeurs d 13 C et d 18 O de micro-échantillons de micrites bien préservées variaient respectivement entre -4,2 % à 0 % « VPDB » et entre -11,3 % à -2,9 % (VPDB). Le profil d 13 C carb des carbonates du Groupe de St. George montre plusieurs changements à des valeurs négatives; ces changements varient entre *2 % à 3 % et ils sont généralement associés à des discordances ou à de minces interlits de shale, reflétant ainsi l'effet des changements importants de niveau de la mer ou ayant un lien avec ces changements. La discordance de St. George est associée à un changement négatif d 13 C carb (*2 %) du profil et elle est corrélée à un important bas niveau dans une reconstruction locale du niveau de la mer (vers la fin de l'Arenigien) ainsi qu'à des bas niveaux dans des régio...

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Section: Methodsmentioning

confidence: 99%

High-resolution isotope stratigraphy of the Lower Ordovician St. George Group of western Newfoundland, Canada: implications for global correlation

Azmy

Lavoie

2009

Can. J. Earth Sci.

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“…It is represented by minimum values of −3 ‰ to −4 ‰ in Australia Miller et al 2006; Fig. 4) or a less pronounced trough in Laurentia (Buggisch, Keller & Lehnert, 2003;Saltzman et al 2004;Miller et al 2006; Fig. 4).…”

Section: The Cambrian-ordovician Boundary In the Kulyumbe Sectionmentioning

confidence: 99%

“…4). Buggisch, Keller & Lehnert (2003) suggested, however, that negative anomalies, such as HERB, could have been produced or enhanced by diagenesis at sequence boundaries rather than representing the true magnitudes of primary oceanic carbon reservoir changes. Although more pronounced, the HERB minimum can be tentatively correlated to an isotopic minimum of −1 ‰ at the boundary between the Kulyumbe and Ujgur formations (HERB?…”

Section: The Cambrian-ordovician 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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“…Although there is a clear faunal turnover starting from the La Silla Formation onwards (Cañas and Carrera, 2003), the major change to truly open-marine settings seems to occur at the boundary between the La Silla and San Juan formations (Cañas, 1999;Buggisch et al, 2003;Thompson et al, 2012). Major type 1 sequence boundaries separate the La Silla Formation from the under-and overlying units (Cañas, 1999;Keller, 1999).…”

Section: Geological Settingmentioning

confidence: 99%

“…2). A detailed carbon isotope record (controlled by conodont assemblages) of the La Silla and San Juan formations was published by Buggisch et al (2003), presenting an intercontinental correlation of the δ 13 C carb curve with biostratigraphically well-constrained records of the U.S.A.…”

Section: Geological Settingmentioning

confidence: 99%

A lowermost Ordovician tabulate-like coralomorph from the Precordillera of western Argentina: a main component of a reef-framework consortium

Carrera¹,

Astini²,

Gómez³

2016

J. Paleontol.

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Abstract.-Although putative corals of uncertain affinities occur in the early Cambrian, the earliest definite tabulate corals have not been described prior to the Early Ordovician in North America. This paper reports a new finding of a tabulate-like coralomorph forming part of biostratigraphically well-constrained reef mounds in the latest Cambrian-Early Ordovician La Silla Formation in the Argentine Precordillera. The oldest record of the coralomorph genus Amsassia is reported and a new species, A. argentina, is erected. The discovery of this genus in the lowermost Ordovician modifies the previously proposed paleogeographic distribution and patterns of origination and migration routes of this coral-like organism. Amsassia argentina n. sp. constitutes a main framework builder together with a complex microbial consortium. This oldest occurrence of Amsassia as a reef builder represents a new record of a skeletal organism in the gap of metazoan reef constructors after the demise of archaeocyaths in the late early Cambrian.

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Carbon isotope record of Late Cambrian to Early Ordovician carbonates of the Argentine Precordillera

Cited by 142 publications

References 35 publications

High-resolution isotope stratigraphy of the Lower Ordovician St. George Group of western Newfoundland, Canada: implications for global correlation

High-resolution isotope stratigraphy of the Lower Ordovician St. George Group of western Newfoundland, Canada: implications for global correlation

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

A lowermost Ordovician tabulate-like coralomorph from the Precordillera of western Argentina: a main component of a reef-framework consortium

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