Resumo

GALLI, Claudia Inés et al. Análisis paleoambiental y procedencia de los depósitos en el extremo suroeste de la sierra de Aconquija, provincia de Catamarca. Rev. Asoc. Geol. Argent. [online]. 2012, vol.69, n.4, pp.596-610. ISSN 0004-4822.

A sedimentological study was carried out to analyze the sedimentary paleoenvironments and the provenance of the sedimentary and volcaniclastic-sedimentary deposits, located in the areas of Atajo hill, Blanco hill and around Capitallitas river, in the Catamarca Province. These units include fluvial red beds of the Hualfin Formation (Eocene-lower Miocene), clastic-volcaniclastic deposits, and mixed primary volcanic deposits, known as the Farallón Negro Volcanic Complex (late Miocene-Pliocene). The Hualfin Formation facies association is characterized by sandy bed-forms, with fewer gravel bars, forming a "shallow perennial sand-bed braided river". The samples of the Huafin Formation show cratonic interior and recycled quartz origin and are composed by quartz arenites generated by the erosion of granitic and gneissic rocks with high percentages of quartz. The paleoenvironment of the deposition of the Farallón Negro Volcanic Complex evolves from a sheetflood distal braided to gravelly braided river systems associated with gravity flows, finally, to a shallow gravelly braided fluvial system. There are three different composition in these deposits: quartz wackes, composed by recycled orogen sandstones derived from the basement; feldesphatic-lithic wackes composed by transitional arc sandstones with a high percentage of lithic volcanic fragments of basalt; and lithic wackes composed by undissected arc sandstones with a high proportion of andesite, glass and plagioclase.

Palavras-chave : Hualfin Formation; Farallón Negro Volcanic Complex; Fluvial braided; Gravity flow.

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