Abstract

LIMARINO, Carlos Oscar; CICCIOLI, Patricia Lucía; KRAPOVICKAS, Verónica  and  BENEDITO, Luis Darío. Estratigrafía de las sucesiones Mesozoicas, Paleógenas y Neógenas de las Quebradas Santo Domingo y El Peñón (Precordillera Septentrional Riojana). Rev. Asoc. Geol. Argent. [online]. 2016, vol.73, n.3, pp.301-318. ISSN 0004-4822.

Geological surveys carried out in the Santo Domingo and El Peñón creeks allow, for the first time, proposing an integrated stratigraphic model for the post-Paleozoic units outcropping in the Precordillera Septentrional. The area encompassing the Santo Domingo and El Peñón creeks is a key section not only for the stratigraphy of the Precordillera but also for regional correlations with units of similar age from the Sierras Pampeanas and north of Chile. Six stratigraphic units between the Late Triassic and the Miocene were recognized. The oldest corresponds to the Santo Domingo Formation, a red bed sequence composed of conglomerates, sandstones and mudstones wich was dated in the Late Triassic-Early Jurassic based on the study of the xyloflora and a radiometric age. This unit is unconformably covered by sandstones and mudstones belonging to the Ciénaga del Río Huaco Formation (Late Cretaceous) which provided some skeletal remains of Titanosaurios. The Puesto La Flecha Formation (late Eocene-Oligocene) comprises sandstones and mudstones deposited in ephemeral fluvial systems together with shallow water bodies (Lower Member) and eolian dunes (Upper Member). The onset of the Andean Orogeny in the studied region is represented in the eolian sandstones of the Vallecito Formation (late Oligocene - early Miocene) which was formed in arid conditions within an underfilled foreland basin. These rocks are succeeded by the informally called unit of “conglomerates and sandstones Refugio del Peñón” that represent the progradation of clastic wedges from the volcanic arc located to the west. Finally, the informal unit of “conglomerates La Falda” points out the displacement towards the west of the Andean orogenic front and the uplift and unroofing of the granitic rocks forming the core of the Sierra del Peñón.

Keywords : Argentine Precordillera; Mesozoic basins; Andean orogeny.

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