Páginas 754-757.

It’s now established that Andean forearc is not concentrating as much tectonic shortening as the foreland since Middle Miocene. GPS measurements are neither available to inform on the long-term deformation across the Andes in Peru and anyway rather describe the elastic response of the Andean forearc to the Nasca-South American Plate convergence. Few neotectonic studies focuses on the Western side of the Andes and little is known about the active deformation in the Central Andes Pacific lowlands (Sébrier et al., 1988). Recent publications mainly improved the description of geomorphic surfaces (Thouret et al. 2007) and cosmogenic dating of the latter show much younger ones than expected (Hall et al., 2008). The topographic gradient on the western side of the Peruvian Andes is quite high as the trench (-7000m) lies only 200km away from the highest point (6000m). Moreover, authors still q...

The southern Pacific coast morphology and especially the presence of marine surfaces gives information on the dynamics of Andean forearc evolution from the Neogene. Along most of the Southern Peru and Northern Chilean coasts, discontinuous uplifts are recorded by marine terraces and marine abrasion surfaces; they have thus, preserved a record of eustatic sea level changes and the uplift history of the coastal area in the Andean forearc. One approach to study the tectonic history of the Andean forearc is to identify its effects in marine sedimentation or erosion patterns along the coastal area. To investigate these processes, the Neogene marine formations are studied in various coastal sections either in southern Peru, at Chala (15°50'S) and Ilo (17°32'S-17°48'S), situated above a steep subduction segment and at San Juan de Marcona (15°20'S), situated above the southern part of the Na...