Paleogeographic boundary in the evolution of the Pucara Basin (Triassic-Liassic) and the Arequipa basin (Lias-Dogger): an inheritance of the block accreted during the Mesoproterozoic

Abstract

Summarizing, the older Cusco-Puno High has a deeper metasomized lerzholithic mantle lithosphere below the Western Altiplano. This block is separated from the Western Cordillera by the C-L-M fault system. Beneath the Eastern Altiplano, corresponds to a Paleoproterozoic to Archaic metasomatized harzburgite mantle. This is added to the presence of the Arequipa Massif (with ages between 1900 and 600 Ma) which is the basement of the Western Cordillera (oldest Arequipa basin). Hence, the lithosphere of the western margin of the South American continent is a mosaic of amalgamated lithospheric blocks (terranes) accreted to Amazonia during the Sunsás orogeny at 1000 Ma. This was a complex collision between a large block, the Arequipa Massif, and other small lithospheric blocks which later formed the substrate for the Western and Eastern Altiplano. If we consider the Totos-Paras High as a prolongation of the Cusco-Puno High, then the substrate would be the same which comes from Cusco-Puno High. This study shows how the older structures control not only Meso-Cenozoic paleogeography, but also Andean deformation.