Conodont biostratigraphy and global correlation of the middle Darriwilian-lower Sandbian (Ordovician) Las Aguaditas Formation, Precordillera of San Juan, Argentina
- Autor Institucional:
- Lugar de Edición:
- Fuente o Serie:
- Andean Geology
- Año, Volumen y Número:
- 2016, Vol 43, No 1
- Número de serie:
- 1
- Páginas:
- Escala:
- Región:
- Fecha:
- 2016, Ene.
- Descripción física:
- digital (pp.60-85)
- Resumen:
- 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. ristinae Subzone that correlates the North American scheme. A stratigraphic gap was recognized tween the lower and middle members of the Las Aguaditas Formation. It comprises the oplacognathus suecicus and Pygodus serra zones, and the lower subzone of the Pygodus anserinus Zone. The riation 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 rovides a more accurate intercontinental correlation for the global Middle Ordovician Series.
- Editor:
- Descripción:
- URI:
- https://repositorio.sernageomin.cl/handle/0104/18969
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