Páginas 83-86.

Counterclockwise tectonic rotations in the northern central Andes and clockwise rotations in the southern Central Andes have been systematically reported (see Roperch et al. 2006 and Arriagada et al., 2006 for a recent summary) and interpreted to be mostly driven by oroclinal bending associated with shortening in the Eastern Cordillera and in the subandean belt. Large counterclockwise rotations have been found in the Eastern Cordillera of Southern Peru (Gilder et al. 2003). While these rotations were initially attributed to a Cretaceous event of deformation, Gilder et al. (2003) interpreted these rotations to be coeval with the rotations found along the forearc (Roperch et al., 2006). Rotations along the forearc from Arequipa to Caravelli are larger than 40° and occurred mainly during the late Eocene - Oligocene. However, the lack of data within the Peruvian Altiplano precludes a good d...

TC6005, 14 p.

Although Andean southern Peru forms the northwestern termination of the Bolivian Orocline, knowledge of its geology has little progressed in the last 20 years, partly due to the civil war that spread in the region during the 1980s and early 1990s. As a consequence, outdated information and concepts are generally still used in current assessments and syntheses, and updated data are needed. This short descriptive contribution presents the principal tectonic elements we currently recognize in southern Peru, and their relationships with syntectonic sedimentary basins. We observe that the most prominent deformational systems in this part of the Bolivian Orocline are dominantly transcurrent, and that many magmatic manifestations are associated with them.

[ENG] Three large transcurrent systems, with related magmatism, are identified in southern Peru. A ∼40-80km-wide, N150-trending, dextral corridor (CECLLA =Cusco-Lagunillas-Laraqueri-Abaroa structural corridor) is characterized by thick Oligocene basic lavas and numerous intrusions. The other two systems are oriented ∼N125-130 and sinistral, and cartographically related to the CECLLA. Miocene to Quaternary basic magmas are associated to the northeastern system (SFUACC = Urcos-Ayaviri-Copacabana-Coniri fault system). In the southwestern region, the abundant Late Cretaceous-Paleocene arc magmatism seems related to the Incapuquio-El Castillo fault system (SFIEC).