The geodynamic evolution of the early Paleozoic Gondwana margin in southern Peru and northern Bolivia – the provenance record of the Ordovician and Devonian siliciclastic strata

Basic data for this project

Description

The Arequipa Massif basement block in the central Andes represents one of the longest-lived enigmas of Andean geology. The geochronological structures of the Arequipa Massif on the coast of southern Peru, and the Sunsas belt on the SW margin of the Amazonia craton in eastern Bolivia are characterized by Transamazonian protoliths affected by Grenville age metamorphism. They differ by events between 1.8 and 1.2, which are only present in the Sunsas belt. Even though the knowledge of its geochronological structure has been refined in the past years, the Arequipa massif's role in the plate tectonic evolution of the proto-Andean margin of South America during the Proterozoic and Early Paleozoic remains obscure. The same is consequently valid also for the Ordovician and Devonian sedimentary basins in southern Peru and northern Bolivia, which developed between the Arequipa Massif and the Sunsas belt.- We will determine the age distribution, and the derivation of the detritus from eastern and/or western sources, in the Ordovician and Devonian deposits in southern Peru and northern Bolivia by applying LA-ICP mass spectrometry to detrital zircons and 40Ar/39Ar geochronology to detrital muscovites. These provenance data, in combination with our sedimentological and geochemical data, will be instrumental in the differentiation of proximal and distal sources, and the reconstruction of the tectonic setting in which the Ordovician and Devonian basins in the northern central Andes evolved.