The ancestors of meandering rivers

Author(s)

de Almeida, Renato Paes ^{[1, 2]} ; Marconato, Andre ^[2] ; Freitas, Bernardo Tavares ^{[2, 3]} ; Turra, Bruno Boito ^[4]

Affiliation

^[1] Univ Sao Paulo, Inst Energia & Meio Ambiente, Ave Prof Luciano Gualberto 1289, BR-05508080 Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Inst Geociencias, Rua Lago 562, Cidade Univ, BR-05508900 Sao Paulo, SP - Brazil

^[3] Univ Fed Itajuba, Inst Recursos Nat, Ave BPS 1303, BR-37500903 Itajuba, MG - Brazil

^[4] CPRM Geol Survey Brazil, Rua Costa 55, BR-01304010 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: GEOLOGY; v. 44, n. 3, p. 203-206, MAR 2016.
• Web of Science Citations: 9

Abstract

Modern alluvial plains, in contrast to their pre-Silurian counterparts, are characterized by the presence of meandering rivers in low-downstream-gradient areas, constituting efficient transport systems that maintain high bottom shear stresses in deep channels, which are made possible by bank stabilization, most commonly provided by vegetation in Earth's recent history. Here we show, through numerical modeling and field-based description of large-scale exposures in Mesoproterozoic successions, that prevegetation rivers in low-downstream-gradient areas were markedly different from both younger meandering rivers and the common prevegetation sheet-braided rivers, showing deeper braided channels and greater floodplain preservation than the latter. These systems were less frequent and had lower transport efficiency than modern meandering rivers, implying differences in global-scale Earth-surface dynamics, from the weathering of silicate minerals in floodplains to the grain size distribution in all clastic depositional systems. (AU)

• FAPESP's process: 11/50280-4 - Architecture of pre-vegetation alluvial systems of the Tombador Formation (Mesoproterozoic, Northeastern, Brazil)
• Grantee: Renato Paes de Almeida
• Support Opportunities: Regular Research Grants