LAS GRAPTOFAUNAS DE LA FORMACIÓN LOS SOMBREROS, ORDOVÍCICO INFERIOR, DE LA VERTIENTE ORIENTAL DE LA SIERRA DEL TONTAL, PRECORDILLERA DE SAN JUAN

Authors

  • A. Cuerda
  • C. A. Cingolani
  • R. Varela

Abstract

GRAPTOLITES FROM THE Los SOMBREROS FORMATION, LOWER ORDOVICIAN IN THE EASTERN SLOPE OF THE TONTAL HILL, PRECORDILLERA FOLD BELT OF SAN JUAN. - An early Ordovician sequence made up by gray limestones and black shales, approximately 1.000 m thick, cropping out in the central Precordillera fold belt (San Juan Province) has be en studied. Structural analysis shows that the sequence is part of a tectonic wedge; low and high angle faults separate it at the base and the top from Upper Devonian-Ordovician rocks. Three graptolitic faunas were díscovered in the lower part of the sequence: the first one is composed by Dictyonema sp., the second one by Callograptus cf. salteri Hall and the third one by Tetragraptus quadribrachiatus (Hall), Tetragraptus amii Elles & Wood, Tetragraptus cf. fruticosus (Hall), Tetragraptus? sp., Phyllograptus anna Hall and Didymograptus sp. The fossil-bearing beds constitute 35 m of the whole sedimentary sequence; the two first graptolitic associatíons are assigned to the Tremadocian and the last one to the Arenigian.

Published

2013-10-05

How to Cite

Cuerda, A., Cingolani, C. A., & Varela, R. (2013). LAS GRAPTOFAUNAS DE LA FORMACIÓN LOS SOMBREROS, ORDOVÍCICO INFERIOR, DE LA VERTIENTE ORIENTAL DE LA SIERRA DEL TONTAL, PRECORDILLERA DE SAN JUAN. Ameghiniana, 20(3-4), 239-260. Retrieved from https://ameghiniana.org.ar/index.php/ameghiniana/article/view/1777

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Articles