The role of tectonic inheritance in the development of an Andean retroarc foreland basin system: The Acre Basin (NW Brazil)

The Andes, located on the western edge of the South American platform, corresponds to a classic example of subduction, which results in one of the most extensive mountain ranges on Earth. However, little is still understood about the area of influence of the fold-thrust belt in the deformation of the distal retroarc region to the east, close to the craton. In this context, Acre Basin is one of the least understood provinces, located in the Peruvian flat slab, a region that involves one of the greatest deformations in the Andes. Therefore, this research aims to understand the tectono-stratigraphic evolution of the Acre Basin and its relationships with the subAndean basins through 2D seismic lines and exploration wells. The definition and mapping of six seismic units aged between the Devonian and the Neogene, confirmed by restoration, indicated a tectonic history compatible with the main events recorded in the sub-Andean basins, marked by an intercalation between extensional rift and compressional regimes, with an important role of basement and structural inheritance in deposition and in the structural style of deformation. Seismic units representative of the Famatinian, Gondwanide, Juru'a and Andean orogenies, and the Pangea breakup were identified. The current positioning of the forebulge was conditioned by a locally non-elastic mechanism of forebulge uplift related to the upper Jurassic basement high (Envira High Arch), Cenozoic reactivation of Triassic rift faults and by the uplift of intraforeland basement blocks in thick-skinned tectonics during the Miocene. Thus, in addition to placing the Acre Basin in the context of sub-Andean basins, these deposits help to understand the geodynamic mechanisms and the complexity of Andean deformation even in regions distal to the fold-thrust belt.