SIGNIFICADO BIOESTRATIGRÁFICO DE UNA ASOCIACIÓN DE TRILOBITES DEL TRAMO BASAL DE LA FORMACIÓN VOLCANCITO (SISTEMA DE FAMA TINA, LA RIOJA, ARGENTINA)

M. Franco Tortello, Susana B. Esteban

Abstract


The Volcancito Formation is an important Lower Palaeozoic unit of the Famatina system (La Rioja Province, Argentina). It is well represented in the Puesto Volcancito area, on the eastern slope of Famatina Range. A classical section of this area belongs to the Parabolina frequens argentina Biozone (Latest Cambrian-Lower Tremadocian). The lower levels of this section contain a fossil assemblage with Lotagnostus? sp., Micragnostus vilonii Harrington and Leanza, Micragnostus calviformis Harrington and Leanza, Gymnagnostus bolivianus (Hoek), Neoagnostus (Machairagnostus] tmetus Harrington and Leanza, Neoagnostus (Machairagnostus) cf. tmetus Harrington and Leanza, Leiagnostus sp., Parabolina (Neoparabolina) frequens (Barrande), Angelina hyeronimi (Kayser), Parabolinella argentinensis Kobayashi, Plicatolina scalpta Harrington and Leanza, Onychopyge riojana Harrington, Asaphellus'I sp. and Shumardia erquensis Kobayashi. This assemblage indicates a latest Carnbrian age.

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