Abstract

ARAOZ, Lucía. Ordovician microfloras of the Sierra de Zenta, Cordillera Oriental Argentina. Ser. correl. geol. [online]. 2009, vol.25, n.1, pp.37-94. ISSN 1666-9479.

This work presents the first integrated research on the Ordovician microfloras recorded in the Sierra de Zenta, NW Argentina (Jujuy and Salta provinces), and was carried out on the basis of systematic analysis of palynomorphs, mainly acritarchs. The Sierra de Zenta is located on a transitional zone between the Cordillera Oriental and the Sierras Subandinas, sharing common characters to with both geological provinces. The northern sector of the Sierra displays similar characters to the Cordillera Oriental, with the presence of the Santa Rosita and Acoite formations (Santa Victoria Group). Although the central and southern sector of the Sierra de Zenta presents a great resemblance to the Sierras Subandinas, there is not a perfect match on the stratigrahy of their Ordovician units. Two geological profiles are described, a continuous one in the northern sector of the Abra de Zenta Abra Límite, and another that is represented by an integrated section relevated in the central part of the sierra, between the Abra Buey Ojo Laguna Verde. The last stratigraphical sector is composed by four partial sections. In the palynological samples the acritarchs are dominant elements, while prasinophyte, chitinozoans and cryptospores represent minor escorting microfossils. Based on acritarchs records, five informal associations were defined whose ages were assigned according to the chronostratigraphical distribution of the taxones components (ASZ). These associations are compared to other Ordovician sequences of Argentina and diverse regions of the world, establishing some partial bioestratigraphical and paleogeographical correlations.

Keywords : Acritarchs; Ordovician; Biostratigraphy; Zenta; Argentina.

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