Abstract

GIAMBIGI, Laura; MESCUA, José; FOLGUERA, Alicia  and  MARTINEZ, Amancay. Structures and kinematics of the pre-Andean deformations of the southern sector of the Precordillera, Mendoza. Rev. Asoc. Geol. Argent. [online]. 2010, vol.66, n.1-2, pp.05-20. ISSN 0004-4822.

The structure of the southern sector of the Precordillera is the result of different deformational events: Eopaleozoic, Neopaleozoic, Permian- Triassic and Cenozoic, each one with particular strike, vergence and style. Many early and late Paleozoic structures have been reactivated during the subsequent tectonic events. The kinematic analysis of Eopaleozoic structures allows us to distinguish between two deformational events with particular kinematic characteristics. The first event, D1, shows an E-W maximum shortening direction and westward vergence. The second event, D2, shows a NW to WNW maximum shortening direction and double vergence. Two models explain this kinematic variation; whether the two events were separated in time and respond to different tectonic events, or they are related to a transpressive event with rotation of the shortening direction through time. The late Paleozoic deformation was characterized by the generation of a thin-skinned fold and thrust belt in the eastern sector and a thick-skinned one in the western sector with reactivation of Eopaleozoic structures. The kinematic analysis indicates a NW-SE shortening direction and double vergence. During the extensional period, from Late Permian to Middle Triassic, the region had a transtensional deformation produced by a NE extensional direction and the reactivation of a NNOoriented preexisting weakness zones. The pre-Andean structures were reactivated during the Andean orogeny, generating a thick-skinned fold and thrust belt with double vergence.

Keywords : Kinematic analysis; Paleozoic evolution; Andes; Tectonic events.

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