Amazonian paleogeography reavaliation on Miocene and Pliocene and establishment of links to numerical integrated models of geodynamic and sedimentary systems

Abstract

The Acre Basin, located in Western most Brazil, is considered the brazilian continuity of the andean Marañón, Ucayali and Madre de Dios foreland basins (Peru), it is the single brazilian basin where the subsidence was related with the andean tectonic, over the Cenozoic. The Acre Basin is also related to the Amazon drainage basin context, therefore represents a link among the andean tectonic and the development of the modern transcontinental Amazon drainage system. The Cenozoic evolution of the Basin is of great relevance to the formation of the landscapes and biota in Amazonia, being central subject of large international research projects in progress, highlighted the Trans-Amazon Drilling Project. Despite its relevance, the Cenozoic units of Acre Basin are not individualized, the entire sequence from Eocene to Pliocene is included in the Solimões Formation, making it difficult to recognize the spatial and temporal variations on sedimentation patterns. The uplift of the Fitzcarrald region in the Pliocene, which induced widespread geographic changes and a regional erosive discordance, is another reason to argue if the outcrops indeed correspond to the Solimões Formation type section or if it match with older units. Based on outcrops descriptions and with the access to boreholes that will be obtained by the Trans-Amazon Drilling Project in Cruzeiro do Sul (AC) and Tefé (AM), as well as with the cosmogenic nuclide datation, models stratigraphically controlled will be elaborated to the paleogeography of the region in Miocene and Pliocene, opposed to the current conceitual models and numerical models of landscape evolution. (AU)