Late Cretaceous through Cenozoic Paleoenvironmental History of the Bagua Basin, Peru: Paleoelevation Comparisons with the Central Andean Plateau

Located in northern Peru, at the lowest segment of Central Andes, Bagua Basin contains a Campanian to Pleistocene sedimentary record that archives local paleoenvironmental and tectonic history. We present new ?18O ?13C signatures pedogenic carbonate nodules from paleosols Campanian–Maastrichtian Fundo El Triunfo Formation upper Eocene–middle Miocene Sambimera reconstruct isotopic composition paleo-meteoric water floristic biome. compare these results modern values newly obtained transect interpret environmental evolution this area its relationship with neighboring Eastern Cordillera. A ~2‰ depletion between latest Cretaceous Eocene reflects shift coastal inland environment. negative ~3‰ middle day reveals establishment Cordillera as an orographic barrier for moisture traveling westward, sometime after deposition top ~13 Ma. signature ~?25‰ Campanian–Miocene deposits ~?23‰ modern–Holocene times suggests change biome dominant C3 plants mixture C4 plants. This both late global expansion transition more arid conditions basin. The Campanian–middle reconstruction indicates steady paleoelevation setting northernmost Andes during most Cenozoic constrains uplift Miocene–Pleistocene. history contrasts Andean Plateau, which is characterized by two major episodes surface uplift: early–middle Miocene–Pliocene. contrasting topographic configuration Plateau gives rise question what factors created such dramatic difference regions shared overall common discuss possible responsible suggest diachronous flat slab are likely factor, resulting greater shortening crustal thickness and, ultimately, earlier occurring Plateau.