Transtensive to transpresive neotectonic reactivation of a fold and thrust belt: The Tromen volcanic plateau in the Southern Central Andes.

SAGRIPANTI, L.; ROJAS VERA, E.A.; GIANNI, G.; RUSCONI, F.; FOLGUERA, A.; RAMOS, V. A.

Simposio; VIII ISAG; 2012

The Southern Central Andes between 36º and 37º S have been affected by several constructional and extensional episodes since 100 Ma, when The Andes started its uplift. Mesozoic to Cenozoic retroarc deposits have been deformed in a fold a trust belt characterized by thick skinned deformation that exposes up to Paleozoic basement rocks (Figure 1a). These structures have produced locally thin-skinned deformational belts, characterized by complex structures detached in marine sediments of the Auquilco-Vaca Muerta Formation (Middle to Late Jurassic - Early Cretaceous), and evaporitic deposits of the Huitrin Formation (Early to Late Cretaceous)(Kozlowski et al., 1993). These structures are buried unconformably by Late Oligocene volcanism and Quaternary stratovolcanoes and caldera complexes in the outer retroarc area. The Tromen volcanic plateau (37º S), constitutes one of those Plio-Quaternary volcanic fields covering vast proportions of the Malargüe fold and thrust belt (Figure 1 a, b) (Holmberg 1975; Zollner and Amos 1973; Kay et al 2006, Galland et al 2007; Folguera et al 2008). This plateau is affected by neotectonic structures whose mechanisms have been intensely discussed in the last years.