LAS ZONAS DE DIDYMOGRAPTUS (DIDYMOGRAPTELLUS) BIFIDUS (ARENIGIANO MEDIO) y DIDYMOGRAPTUS (CORYMBOGRAPTUS) DEFLEXUS (ARENIGIANO INFERIOR) EN LA FORMACION ACOITE, CORDILLERA ORIENTAL, ARGENTINA

Blanca A. Toro

Abstract


The occurrence of Didymograptus (Didymograptetlus) bifidus (J. Hall) was recorded at the western flank of the Cordillera Oriental (Argentina). The fossil-bearing strata belongs to the Acoite Formation outcropping in the Chamarra section at the Jujuy Province. The analized graptolite assemblages have allowed to recognize the Didymograptus (Corymbograptus) deflexus Zone and the Didymograptus (Didymograptellus) bifidus Zone. These biozones indicate an Early Arenig to Middle Arenig age for the studied sequence. The diagnostic assemblages from both biozones, the taxa distribution, the age and the paleobiogeographic affinities are discussed. Moreover, a correlation with other Lower Ordovicinn sections of the Cordillera Oriental is proposed.

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