EVOLUTION OF SHALLOW AND DEEP STRUCTURES ALONG THE MAIPO-TUNUYÁN TRANSECT (33°40´S): from the Pacific coast to the Andean foreland

LAURA GIAMBIAGI; ANDRÉS TASSARA, JOSÉ MESCUA, MAISA TUNIK

JOURNAL OF THE GEOLOGICAL SOCIETY

GEOLOGICAL SOC PUBL HOUSE

Lugar: Londres; Año: 2015 vol. 399 p. 63 - 82

0016-7649

We propose an integrated kinematic model with mechanical constrains of the Maipo-Tunuyán transect (33°40´S) across the Andes. The model describes the relation between horizontal shortening, uplift, crustal thickening and activity of the magmatic arc, while accounting for the main deep processes that have shaped the Andes since the early Miocene. We construct a conceptual model of the mechanical interplay between deep and shallow deformational processes, which considers a locked subduction interface cyclically released during megathrust earthquakes. During the coupling phase, long-term deformation is confined to the thermally and mechanically weakened Andean strip, where plastic deformation is achieved by movement along a main décollement located at the base of the upper brittle crust. The model proposes a passive surface uplift in the Coastal Range as the master décollement decreases its slip eastward transferring shortening to a broad area above a theoretical point, S, where the master detachment touches the Moho horizon. Once the crustal root achieves its actual thickness of 50 km, between 12-10 Ma, it resists further thickening and gravity driven forces, and thrusting shifts eastwards into the lowlands achieving a total Miocene-Present amount of shortening of 71 km.