Cenozoic weathering of fluvial terraces and emergence of biogeographic boundaries in Central Amazonia

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Gautheron, Cecile ; Sawakuchi, Andre O. ; dos Santos Albuquerque, Marcio F. ; Cabriolu, Cristiana ; Parra, Mauricio ; Ribas, Camilla C. ; Pupim, Fabiano N. ; Schwartz, Stephane ; Kern, Andrea K. ; Gomez, Sebastian ; de Almeida, Renato P. ; Horbe, Adriana M. C. ; Haurine, Frederic ; Miska, Serge ; Nouet, Julius ; Findling, Nathaniel ; Riffel, Silvana Bressan ; Pinna-Jamme, Rosella

• Tipo de documento: Artigo Científico
• Fonte: GLOBAL AND PLANETARY CHANGE; v. 212, p. 18-pg., 2022-04-19.

Resumo

The study of paleofluvial dynamics is crucial to understand the role of rivers as biogeographic boundaries in Amazonia during the Cenozoic. In central Amazonia, Mesozoic and Cenozoic fluvial deposits -Alter do Chao, Iranduba and Novo Remanso Formations-host supergene iron oxides and record changes in the distribution of flooded and non-flooded (upland) environments. Geochronological data on these deposits are still scarce to constrain past landscape changes. Therefore, in this study we investigate iron oxides precipitated within weathering profiles developed on ancient fluvial terraces to access the interplay between flooded and non-flooded environments in central Amazonia. We aimed to trace the history of abandonment of alluvial plains and the subsequent weathering of lowland sediment deposits during the Cenozoic. We identified at least two main periods of iron oxide precipitation: (1) one starting before similar to 42 Ma and ending at similar to 18 Ma; and (2) a well-defined humid and weathering prone phase between-8 and 1 Ma. Dominant goethite precipitation marks a major climatic shift towards more humid conditions from similar to 3 Ma. The increase in water discharge of the Negro and Solimoes rivers possibly promoted fluvial incision and conversion of floodplains into long-lasting upland terrains as indicated by the development of lateritic weathering profiles. This major phase of upland expansion corroborates upland birds phylogenetic data, which indicate the emergence of a major biogeographic barrier in central Amazonia during late Pliocene/Pleistocene. (AU)

• Processo FAPESP: 14/23334-4 - Reconstrução de mudanças no sistema fluvial da Amazônia durante o Cenozoico tardio (<5 Ma) por meio da integração de análises por luminescência opticamente estimulada (OSL) e nuclídeos cosmogênicos (TCN).
• Beneficiário: Fabiano do Nascimento Pupim
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 18/23899-2 - Projeto de Perfuração Transamazônica: origem e evolução das florestas, clima e hidrologia dos trópicos da América do Sul
• Beneficiário: André Oliveira Sawakuchi
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático
• Processo FAPESP: 13/03265-5 - Processos de superfície durante orogênese ativa: soerguimento e erosão da Serra Nevada de Santa Marta (Colômbia) em escalas múltiplas de tempo
• Beneficiário: Mauricio Parra Amézquita
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores