Geodynamic Processes in the Andes of Central Chile and Argentina
This Special Publication arises from the UNESCO-sponsored IGCP 586-Y project ‘The tectonics and geomorphology of the Andes (32°–34°S): interplay between short-term and long-term processes’. It includes state-of-the-art reviews and original articles from a multidisciplinary perspective that investigate the complex interactions of tectonics and surface processes in the subduction-related orogen of the Andes of central Chile and Argentina (c. 27°–39°S). It aims to improve our understanding of tectonic and landscape evolution of the Andean range at different time scales, as well as the mutual relationship between internal and external mechanisms in Cenozoic deformation, mountain building, topographic evolution, basin development and mega-landslides occurrence across the flat slab to normal subduction segments. The geodynamic processes of the Andes of central Chile and Argentina are analysed from a number of subdisciplines of the Earth sciences, including tectonics, petrology, geophysics, geochemistry, structural geology, geomorphology, engineering geology, stratigraphy and sedimentology.
Evolution of shallow and deep structures along the Maipo–Tunuyán transect (33°40′S): from the Pacific coast to the Andean foreland
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Published:January 01, 2015
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CiteCitation
Laura Giambiagi, Andrés Tassara, José Mescua, Maisa Tunik, Pamela P. Alvarez, Estanislao Godoy, Greg Hoke, Luisa Pinto, Silvana Spagnotto, Hernán Porras, Felipe Tapia, Pamela Jara, Florencia Bechis, Víctor H. García, Julieta Suriano, Stella Maris Moreiras, Sebastían D. Pagano, 2015. "Evolution of shallow and deep structures along the Maipo–Tunuyán transect (33°40′S): from the Pacific coast to the Andean foreland", Geodynamic Processes in the Andes of Central Chile and Argentina, S. A. Sepúlveda, L. B. Giambiagi, S. M. Moreiras, L. Pinto, M. Tunik, G. D. Hoke, M. Farías
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Abstract
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 Early Miocene time. 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 eastwards, transferring shortening to a broad area above a theoretical point S where the master detachment touches the Moho horizon. When the crustal root achieves its actual thickness of 50 km between 12 and 10 Ma, it resists further thickening and gravity-driven forces and thrusting shifts eastwards into the lowlands achieving a total Miocene–Holocene shortening of 71 km.