Conodont and Graptolite Biostratigraphy of the Ordovician System of Argentina

Albanesi, Guillermo L.; Ortega, Gladys

doi:10.1016/bs.sats.2016.10.002

Cited by 79 publications

(69 citation statements)

References 48 publications

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“…7 m above SJF10, Pa elements of L. variabilis were recovered confirming its presence. Sample SJF9 carries elements of P. horridus primus and P. horridus secundus, which indicate the P. horridus Subzone of the L. variabilis Zone defined by Albanesi and Ortega (2002) for regional correlation, and recently well documented by Carrera et al (2013) Albanesi and Barnes (2000) occurs in the studied section between samples SJF9 and SJF0. In the oldest sample, the ancestor P. originalis was recovered along with the intermediate forms, Paroistodus h. primus and Paroistodus h. secundus, and 4 m higher (SJF7) the derived species, P. h. horridus, makes its entrance in lower frequency than the older species.…”

Section: Lenodus Variabilis Zonementioning

confidence: 99%

“…The first formal conodont-graptolite biostratigraphic scheme for the middle Darriwilian of the Precordillera was published by Albanesi et al (1995b and later revised by Albanesi and Ortega (2002 (Fig. 3).…”

Section: Conodont Biostratigraphymentioning

confidence: 99%

“…The conodont species L. variabilis has previously been reported from the San Juan and Gualcamayo formations in the Villicum Range (Sarmiento, 1985;Heredia and Mestre, 2013a,b;Mestre, 2013), and at Cerro Viejo of Huaco (Ottone et al, 1999;Ortega et al, 2007), in the uppermost part of the San Juan Formation at Portezuelo de Yanzo and Cerro Potrerillo (Ortega et al, 1995;Albanesi and Ortega, 2002), and also in the Yerba Loca Formation from the western Precordillera (Albanesi et al, 1995b).…”

Section: Regional and Global Correlationmentioning

confidence: 99%

“…3). Additionally, the Lenodus variabilis Zone with its Periodon gladysae and Paroistodus horridus subzones which were proposed by Albanesi and Ortega (2002) for the Precordillera, were also identified, following the emendation by Carrera et al (2013). The uppermost biozone identified in the studied section is the upper subzone of the Pygodus anserinus Zone, of Sandbian age (Fig.…”

Section: Conodont Biostratigraphymentioning

confidence: 99%

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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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Section: Lenodus Variabilis Zonementioning

confidence: 99%

Section: Conodont Biostratigraphymentioning

confidence: 99%

Section: Regional and Global Correlationmentioning

confidence: 99%

Section: Conodont Biostratigraphymentioning

confidence: 99%

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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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“…The age of the La Silla Formation has been established by combining information from conodonts and sparse trilobites (Lehnert and Keller, 1993;Keller et al, 1994;Lehnert, 1995;Lehnert et al, 1997;Albanesi and Ortega, 2002). The trilobite Plethopeltis obtusus (Rasetti, 1945), which in North America ranges from the Saukia to the Missisquoia trilobite zones, has been found near the base of the unit (Vaccari, 1994), indicating a late Sunwaptan (late Furongian) age for this part of the section.…”

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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Lower middle Darriwilian (Ordovician) graptolites and index conodonts from the Central Precordillera of San Juan Province, Argentina

et al. 2017

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This study includes 3 localities from the Jáchal area in the Central Precordillera of San Juan Province, from north to south: the Oculta creek, Las Aguaditas creek, and Cerro La Chilca sections. We deal with the graptolite faunas and conodont index species recorded from units that overlie the carbonate San Juan Formation, spanning the lower part of the Los Azules, Las Aguaditas, and Gualcamayo formations in their respective areas. The index graptolites and associated species are reported, which enable the recognition of the Levisograptus dentatus Zone in the Central Precordillera. The presence of graptolites in the limestones from the top of the San Juan Formation at the Cerro La Chilca section is documented for the first time. The record of representatives of the Lenodus variabilis, Yangtzeplacognathus crassus, Eoplacognathus pseudoplanus, Histiodella, and Periodon lineages recognized in these units, linked with respective graptolite zones, provide precise information for global correlation purposes. The use of conodont and graptolite zones from different areas of the Central Precordillera enables the verification of the diachronous contact between the San Juan Formation and overlying units, which spans the lower to middle Darriwilian, in our investigated sections and classical localities previously documented.

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Conodont and Graptolite Biostratigraphy of the Ordovician System of Argentina

Cited by 79 publications

References 48 publications

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

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

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

Lower middle Darriwilian (Ordovician) graptolites and index conodonts from the Central Precordillera of San Juan Province, Argentina

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