High resolution conodont-graptolite biostratigraphy in the Middle-Upper Ordovician of the Sierra de La Invernada Formation (Central Precordillera, Argentina)

Authors

  • G. ORTEGA CONICET - Museo de Paleontología, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de CórdobaCC 1598, 5000 Córdoba, Argentina.
  • G.L. ALBANESI IANIGLA-CRICyT-CONICET, Departamento de Geología y PaleontologíaAv. Adrián Ruiz Leal s/n, Parque General San Martín, 5500 Mendoza, Argentina
  • A.L. BANCHIG IANIGLA-CRICyT-CONICET, Departamento de Geología y PaleontologíaAv. Adrián Ruiz Leal s/n, Parque General San Martín, 5500 Mendoza, Argentina
  • G.L. PERALTA Departamento de Geología, Universidad Nacional de San JuanIgnacio de La Rosa y Meglioli s/n, 5400 Rivadavia, San Juan, Argentina

Keywords:

Graptolites Conodonts, Ordovician, Argentine Precordillera.

Abstract

Outcrops on the western slope of the La Invernada Range, San Juan Precordillera (W Argentina), were surveyed for lithofacial analysis and graptolite-conodont high resolution biostratigraphy. The study profile for the upper Sierra de La Invernada Formation is approximately 500 m thick and is located in the northern part of the La Invernada Range. Successive shallowing-deepening sedimentary cycles crop out throughout the upper part of the formation. The dominantly lower turbiditic sandy deposits alternate with shaly pelagic sedimentation, and occasional coarser intervals that record gravitational flows. Hummocky structures occur in the uppermost part of the formation, indicating sedimentation under storm weather conditions. Rich graptolite faunas representing six upper Middle to lower Upper Ordovician biozones have been recorded from this section: Pterograptus elegans (tentative assignment), Hustedograptus teretiusculus, Nemagraptus gracilis, Climacograptus bicornis, Diplacanthograptus caudatus, and Climacograptus tubuliferus biozones. This graptolite biostratigraphy is complemented by the conodont records from successive productive levels, which yielded conodonts that represent the Pygodus serra, P. anserinus, Amorphognathus tvaerensis, and A. superbus biozones. The recorded conodont-graptolite assemblages allow for a correlation with the upper Darriwilian, Sandbian and lower Katian global stages, and provide preliminary biofacies records for the upper Sierra de La Invernada Formation.

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Published

2009-04-22

How to Cite

1.
ORTEGA G, ALBANESI G, BANCHIG A, PERALTA G. High resolution conodont-graptolite biostratigraphy in the Middle-Upper Ordovician of the Sierra de La Invernada Formation (Central Precordillera, Argentina). GeA [Internet]. 2009Apr.22 [cited 2021Sep.17];6(2):161-80. Available from: https://revistes.ub.edu/index.php/GEOACTA/article/view/105.000000249