293 p.

227 p.

123 p.

Se presenta una reseña de la morfología y la geología, como características generales de la zona de estudio. Se describen los movimientos de tierra con el detalle de cada caso, incluyendo uno antiguo de Orccopuquio y el de la zona de alrededores del cementerio. Igualmente se evalúan las causas de los deslizamientos y factores relacionados: a) erosión regresiva; b) presencia de arcillas y yesos; c) régimen climático alternado ,de estación seca a otra lluviosa. Se evalúan los peligros y se aportan las recomendaciones del caso, tanto para áreas urbana como para áreas cultivadas.

12 páginas

The main part of the basement of the Peruvian and Bolivian Andes is formed by the remnants of a Hercynian intracratonic range in which some elements of the Precambrian basement are reworked. The Hercynian sedimentary prism is made of thick detrital Lower Paleozoic sediments, which are partly flysch-like but seem to be never associated with ophiolites. Those sediments were strongly disturbed by the Upper Devonian « Eohercynian » folding ; they display close folds with axial-plane cleavage which result of at least two subphases of deformation, in some areas a greenschist facies metamorphism is associated with the folds. On the whole the range does not show any preferential vergence. The Eohercynian folded complex and its unconformable caver of Carboniferous and Lower and Middle Permian sediments are reworked at the end of the Middle Permian by the Late Hercynian movements which in Peru a...

In the Huancayo-Jauja intra-Andean basin, whose origin seems to be linked to a warping of the «Puna» tertiary erosion surface, an important set of quaternary formations was deposited. The oldest one is the «Jauja» lacustrine formation; the following ones constitute t', t'' and t''' terraces, each one of them being contemporaneous with one glaciation stage. New observations allow to prove that the «Jauja » and t''' formations have been folded, generating a System of narrow anticlinal ripples as also large, flat synclinal basins. The terraces sedimentation and the deepening of the rio Mantaro gorges below the basin were also partly conditioned by a block tectonics which appears to continue at the present time. These new facts are then replaced into the frame of the basin and of the area climatic evolution, in the Quaternary.

4 páginas

pp. 69-75

The peruano•bolivian segment of the Andes is about 2500 km long and its direction is NW-SE north of 18° S, submeridian further south. Its frame made of precambrian and hercynian folded material, constitutes a sialic basement for the Andean orogenic belt. From a stratigraphical point of view, the peruano-bolivian Andes appear as an intracratonic chain, where continental or neritic series prevail. The paleogeographic evolution is controlled by a system of two or three basins separated by rises and generally oriented parallel to the future chain; its most internal element is a high zone, where an intense volcanic activity has been remarkably constant in time and. space during the Mesozoic. The chain built up through three brief and homo•axial tectonic phases occurring respectively at the end of the Cretaceous, the end of the Eocene and the mid•Pliocene, that develop a moderate foldin...