2. Stratigraphic Framework and Time Slices

Webby, Barry D.; Cooper, Roger A.; Bergström, Stig M.; Paris, Florentin

doi:10.7312/webb12678-003

Cited by 148 publications

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“…Currently three algorithms exist, which allow for a correlation of the set of stratigraphic units within established and standard chronostratigraphic schemes of the Ordovician Period (Ordovician Time Slices, TS, Webby et al, 2004;Ordovician Stage Slices, StS, Bergström et al, 2009;and Ordovician Global Stages, Cooper et al, 2012). The algorithms are written in R-code and are available under a GNU General Public License at github.com/bjoekroe/RNames.…”

Section: Application Of Correlation Schemesmentioning

confidence: 99%

RNames, a stratigraphical database designed for the statistical analysis of fossil occurrences – the Ordovician diversification as a case study

Kröger

Lintulaakso

2017

Palaeontologia Electronica

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Section: Application Of Correlation Schemesmentioning

confidence: 99%

RNames, a stratigraphical database designed for the statistical analysis of fossil occurrences – the Ordovician diversification as a case study

Kröger

Lintulaakso

2017

Palaeontologia Electronica

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“…2; Videt et al 2010, Gutiérrez-Marco et al 2013) and its chronostratigraphic setting is interpolated between the top of the widespread Armorican Quartzite, dated as mid-Florian by means of chitinozoans of the Eremochitina brevis Zone, and the occurrence of pendent didymograptids (Darriwilian 2) in overlying shales. This ambiguous situation led to common modifications of the Dapingian chronostratigraphic subdivision, from considering a single ornensis Zone placed in the "upper Dapingian" (Paris in Webby et al 2004, Paris et al 2007b, followed by a "lower Dapingian" ornensis Zone and an "upper Dapingian" henryi Zone (Paris in Chen et al 2009), to an essentially "upper Dapingian" combination of both biozones (Videt et al 2010; for further discussion, see Gutiérrez-Marco et al 2013). The biostratigraphic data reported above do not contradict a possible late Floian age of the chitinozoan assemblage from sample MG10002.…”

Section: Chitinozoansmentioning

confidence: 99%

Dapingian-lower Darriwilian (Ordovician) stratigraphic gap in the Faraghan Mountains, Zagros Ranges, south-eastern Iran

Ghavidel‐Syooki¹,

Popov²,

Álvaro³

et al. 2014

Bull. Geosci.

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The Lower-Middle Ordovician sediments exposed in the Faraghan Mountains, south-eastern Zagros Ranges, represent a condensed succession of siliciclastic-dominated rocks rich in palynomorph assemblages (acritarchs and subsidiary chitinozoans) and sparse shelly concentrations bearing biostratigraphically significant brachiopods and conodonts. The Lower Ordovician Zard-Kuh Formation comprises coarse-grained siliciclastic deposits rich in Cruziana ichnofossils. The lower 80 m of the overlying Seyahou Formation, late Floian to Katian in age, form a heterolithic succession composed of black and green shales, subarkoses and silty limestones. Its lower part is punctuated by a centimetric phosphoarenite that contains lingulate brachiopods (Atansoria yaseri sp. nov.) and conodonts (Baltoniodus aff. B. triangularis Lindström and Drepanoistodus sp.) that suggest a latest Floian age. The top of the condensed phosphoarenite is marked by a considerable hiatus that ranges the Dapingian and early Darriwilian interval. Overlying the hiatus, the Seyahou Formation comprises two fossiliferous levels, the oldest dated as mid-Darriwilian with chitinozoans characteristic of the Siphonochitina formosa Zone, and the youngest of the Katian Acanthochitina barbata Zone. Mid Ordovician phosphogenesis associated with starvation, reworking, resedimentation, and the onset of distinct stratigraphic gaps was a complex process recorded throughout the Arabian margin of Gondwana. In the Zagros Ranges, maximum flooding and phosphate precipitation are suggested as the counterpart of the Helskjer Drowning Event of Baltoscandia and the third-order maximum flooding surface that punctuates the Siphonochitina formosa Zone in North Africa.•

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“…This condition is supported by the record of K-bentonite levels in the transition between the San Juan and the overlying units (Huff et al, 1997). Another possible cause is a decrease in the sea water temperature as a consequence of the migration of the Precordillera to higher latitudes and a sea level rise of global scale (Astini, 1995;Webby et al, 2004).…”

Section: Las Aguaditas Formationmentioning

confidence: 99%

Conodont biostratigraphy and global correlation of the middle Darriwilian-lower Sandbian (Ordovician) Las Aguaditas Formation, Precordillera of San Juan, Argentina

Feltes

Albanesi

Bergström

2016

andgeo

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ABSTRACT. Middle Darriwilian to lower Sandbian conodonts were recorded from the Las Aguaditas Formation at its type section in the Argentine Precordillera. A total of 9,974 conodont specimens were recovered from 46 carbonate samples, which represent 68 species of 38 genera. A biostratigraphic study verified a middle Darriwilian age for the interval spanning the contact between the San Juan and the Las Aguaditas formations. The following zones are determined in the study section: the Lenodus variabilis Zone, with the Periodon gladysae and Paroistodus horridus subzones following the Precordilleran scheme; the L. variabilis, Yangtzeplacognathus crassus, and the Eoplacognathus pseudoplanus zones with the Microzarkodina hagetiana and M. ozarkodella subzones, and the Pygodus anserinus Zone, according to the Scandinavian scheme; the Periodon macrodentatus Zone, with the Histiodella sinuosa, H. holodentata and H. cf. holodentata subzones, and the P. zgierzensis Zone with the H. kristinae Subzone that correlates the North American scheme. A stratigraphic gap was recognized between the lower and middle members of the Las Aguaditas Formation. It comprises the Eoplacognathus suecicus and Pygodus serra zones, and the lower subzone of the Pygodus anserinus Zone. The variation of conodont diversity through the study section conforms to shallowing and deepening patterns, which accompanies the changes of the provenance lithology. Three conodont assemblages were quantitatively recognized: a) Diverse conodont association, b) Low diversity conodont association and c) Recovery phase association. We propose to use the North American biozonal scheme of conodonts for the Central Precordillera because of the affinity of documented index taxa, which provides a more accurate intercontinental correlation for the global Middle Ordovician Series. Keywords: Conodont, Darriwilian-Sandbian, Biostratigraphy, Paleoecology, Precordillera, Argentina. RESUMEN. Bioestratigrafía de conodontes y correlación global del Darriwiliano medio-Sandbiano inferior (Ordovícico) Formación Las Aguaditas, precordillera de San Juan, Argentina. En la Formación Las Aguaditas, en su sección tipo en la precordillera Argentina, se registraron conodontes del Darriwiliano medio al Sandbiano bajo. Se recuperaron un total de 9.974 especímenes de 46 muestras carbonáticas; estos representan 68 especies pertenecientes a 38 géneros. Se llevó a cabo un estudio bioestratigráfico para verificar la edad del intervalo que incluye el contacto entra las formaciones San Juan y Las Aguaditas. La presencia de taxones guía indican una edad darriwiliana media para este intervalo. Las siguientes biozonas fueron determinadas en el área de estudio: Zona de Lenodus variabilis, con las subzonas de Periodon gladysae y Paroistodus horridus, correspondientes al esquema establecido para la precordillera; las zonas de L. variabilis, Yangtzeplacognathus crassus y la de Eoplacognathus pseudoplanus con la subzonas de Microzarkodina hagetiana y M. ozarkodella, y la Zona de Pygodus anserinus, según el ...

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2. Stratigraphic Framework and Time Slices

Cited by 148 publications

References 0 publications

RNames, a stratigraphical database designed for the statistical analysis of fossil occurrences – the Ordovician diversification as a case study

RNames, a stratigraphical database designed for the statistical analysis of fossil occurrences – the Ordovician diversification as a case study

Dapingian-lower Darriwilian (Ordovician) stratigraphic gap in the Faraghan Mountains, Zagros Ranges, south-eastern Iran

Conodont biostratigraphy and global correlation of the middle Darriwilian-lower Sandbian (Ordovician) Las Aguaditas Formation, Precordillera of San Juan, Argentina

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