Rift systems at continental margins: A case study of facies evolution and provenance of the sedimentary-volcanic facies evolution of the Permotriassic Mitu Group (Central Andes, Peru)

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The Permian-Jurassic Mitu Rift System in the Peruvian Andes marks the crucial transition from an accretionary (Neoproterozoic-Paleozoic) to the modern Andino-type continental margin, which exists since the Jurassic. Despite its geodynamic importance the Mitu Rift System is not well studied and understood. Consequently it remains unclear in which way basin structures, and the thicknesses and distribution of the basin fill have influenced Andean mountain building. Centered in the Urubamba valley near Cusco the proposed project combines a detailed analysis of volcanisedimentary facies with provenance analytical studies of single- and multi-grain heavy mineral samples including petrography, geochronology, geochemistry and isotope geochemistry. This will result, for the first time, in geographically resolved maximum depositional ages of different basin parts as well as the determination of variable inputs from different source areas. This will induce an enhanced temporal and spatial resolution of the units building the basin fill architecture. The combination of facies and provenance data will allow for deciphering temporal and spatial variations in the depositional development, and consequently of the basin itself. Finally, these data will constrain the influence of structures and sedimentary fill of the Mitu basin on mountain building of the Andean chain.