Abstract

VATTUONE, M.E.  and  LATORRE, C.O.. K/Ar ages from east Nahuel Pan hills, Chubut. Implicance in the Divisadero and Choiyoi Groups correlation. Rev. Asoc. Geol. Argent. [online]. 2004, vol.59, n.3, pp.510-513. ISSN 0004-4822.

A sequence of dacitic/andesitic flows and pyroclastic rocks, in discordance above basandesitic volcanic series at eastern Nahuel Pan hills, has been dated by K/Ar method. Samples of the flows and basandesitic volcanic rocks yield ages of 105 ± 5 Ma and 252 ± 10 Ma. These ages assign to the lavic-pyroclastic sequence a Cretaceous age (at the lower part of upper member of Divisadero Group) and to the basandesitic volcanic rocks a Permotriassic age (in line with Choiyoi Group). This is the first occurrence, of the Choiyoi Group, in the eastern slope of the Andes at this latitude.

Keywords : K/Ar ages; Cretaceous/Permotriassic volcanic rocks; Nahuel Pan; Chubut.

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