Miocene drainage reversal of the Amazon River driven by plate–mantle interaction

Abstract

Northern South America experienced significant changes in drainage patterns during the opening of the South Atlantic Ocean. Disappearance of a mega-wetland in the western Amazonian basins was followed by the formation of the eastward-draining Amazon River, which has been attributed to Andean uplift [1][2][3][4][5] . However, South America's westward motion over cold, dense subducted slabs implies that regional subsidence and uplift east of the Andes may have been driven by mantle convection. Here we use a coupled model of mantle convection and plate kinematics to show that dynamic subsidence of up to 40 m Myr . The resulting progressive tilt of northern South America to the east enabled the establishment of the Amazon River, suggesting that mantle convection can profoundly affect the evolution of continental drainage systems.During the Early Miocene (from ∼23 Myr bp), an inland fluviolacustrine/marginally marine Amazonian system partially flooded northwest South America with regional drainage mainly northwards towards the Caribbean 1-4 . This Amazonian megawetland existed at least from the Middle to Late Miocene 1,2 when the dominant fluvial drainage switched to its present course towards the Atlantic. This shift, initiating the fluviolacustrine system that is now the Amazon River is supported by sediment provenance, palaeo-transport direction and biostratigraphic studies [1][2][3]5 . The timing of this onset is estimated from offshore sedimentary records between 10.6 and 9.7 Myr bp (ref. 6). Any possible AmazonianCaribbean connection was fully closed by the Late Miocene 2 , with the Amazon River reaching its present shape and size from the Pleistocene onwards 2,7 (∼2.4 Myr bp). During the Early and Middle Miocene a restricted eastward-flowing palaeo-Amazon River may have drained to the Atlantic coast 7 . Stratigraphic data suggest that this fluvial system extended westward until limited by the Purus arch 7 (Fig. 1), a structural high that separated the Solimões and Amazonas basins and restricted the Amazonian mega-wetland to the west and the palaeo-Amazon River to the east.The main Miocene changes in drainage patterns, and the formation of the Amazon River, are commonly attributed to uplift in the northwest Andes 5,[8][9][10][11] . It has been proposed that the uplift of the Eastern Cordillera caused flexural subsidence in the foreland basins, and redirected a significant portion of the northwest Amazonas basin drainage, along the northward-flowing Palaeo-Orinoco and Magdalena rivers, to the east 2 . In addition, it has also been suggested that Amazon landscape evolution can be attributed to Early Tertiary to Holocene intraplate tectonics, including subsidence associated with a low-rate extension that contributed to a structural low 12 . The Late Miocene (∼11 Myr bp) is also well documented for a significant drop in sea level, which would have contributed to the disappearance of the Amazonian mega-wetland and marine incursions 13,14 , but could not have caused a fundamental change in the continental drainage pa...

Eustatic and tectonic change effects in the reversion of the transcontinental Amazon River drainage system

“…This uplifted area is the site of numerous Neogene bauxitic and no-bauxitic plateaus, higher in the basin flanks and lower close to the central basin axis area. Large plateau tops reached about 250 m above sea level, according to SRTM 90 m digital elevation model (DEM) from NASA, as opposed to the conclusions of Shephard et al (2010), who stated subsidence lowered central and eastern basins of northern South America driven by mantle convection, from 14 Myr ago to date. Sacek (2014) concluded that the reversal of the Amazon River can be interpreted by the dynamics of surface processes and the flexure of the lithosphere in response to the formation of the Andes instead of regional uplift guided by mantle convection as proposed by Shephard et al (2010), but Sacek's (2014) hypothesis also fails to fully reproduce the area stratigraphic development.…”

“…Castro et al (1978 andShephard et al (2010) suggested it to have taken place in the Middle Miocene time; Hoorn et al (1995) and Figueiredo et al (2009) in the Late Miocene; Espurt et al (2007) and Roddaz et al (2005) not before the Pliocene; Latrubesse et al (2010), Campbell et al (2006) and Campbell (2010) in the Late Pliocene; and Almeida (1974) in the PlioceneEarly Pleistocene. Bezerra (2003), Rossetti et al (2005) and Bezerra and Ribeiro (2015) inferred the Amazon River to have flowed through the Tacutu Rift, the Essequibo River and the coast of Guyana Republic to the Atlantic Ocean in the Plio-Pleistocene and at the end of the Pleistocene and in the Holocene, being guided to its present valley site, by following neotectonic faults.…”

Eroding dynamic topography

“…1 ISTerre Université de Grenoble 1, CNRS-IRD, F-38041 Grenoble, France. perturbation to oceanic circulation [Poore and White, 2011], large scale continental drainage reorganizations [Shephard et al, 2010] or the formation of major geomorphic features such as the Grand Canyon [Karlstrom et al, 2008].…”

Palinoestratigrafia da Formação Solimões: comparação entre bioestratigrafia tradicional e o método de Associações Unitárias

“…A principal mudança ao longo do desenvolvimento do sistema amazônico ocorreu no Mesomioceno-Neomioceno, com a inversão da direção de fluxo do sistema fluvial, que passou a drenar para o Oceano Atlântico (Hoorn et al, 1995(Hoorn et al, , 2010Shephard et al, 2010). Esse evento pode ser sustentado pela origem da foz do Rio Amazonas no Oceano Atlântico no período entre 11.8 e 8.3 Ma (Figueiredo et al, 2009;Gorini et al, 2014).…”

“…As idades atribuídas para Formação Solimões variam entre Mioceno e início do Plioceno (Hoorn, 1993;Leite, 2006;Leite et al, 2016;Silva-Caminha et al, 2010) O ambiente de deposição da Formação Solimões é predominantemente lacustre e fluvial, com episódios de incursões marinhas registrados por alguns autores no Mioceno inferior e médio/superior (Maia et al, 1977;Hoorn, 1993;Hoorn et al, 1995Hoorn et al, , 2010Cozzuol, 2006;Lovejoy et al, 2006;Latrubesse et al, 2007Latrubesse et al, , 2010Silva-Caminha et al, 2010;Shephard et al, 2010;Linhares et al, 2011;Boonstra et al, 2015).…”