Pleistocene-Holocene sedimentation of Solimões-Amazon fluvial system between the tributaries Negro and Madeira, Central Amazon

Brazilian Journal of Geology. 46(2):167-180 DOI 10.1590/2317-4889201620160009

 

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Journal Title: Brazilian Journal of Geology

ISSN: 2317-4889 (Print); 2317-4692 (Online)

Publisher: Sociedade Brasileira de Geologia

Society/Institution: Sociedade Brasileira de Geologia (SBG)

LCC Subject Category: Science: Geology

Country of publisher: Brazil

Language of fulltext: Portuguese, Spanish; Castilian, French, English

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AUTHORS

Eliezer Senna Gonçalves Júnior
Emílio Alberto Amaral Soares
Sonia Hatsue Tatumi
Marcio Yee
Juan Carlos Ramirez Mittani

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Time From Submission to Publication: 11 weeks

 

Abstract | Full Text

ABSTRACT: In the scope of Solimões-Amazon fluvial system between the Negro and Madeira tributaries, three levels of Quaternary fluvial terraces overlie the Alter do Chão and Novo Remanso formations further than 100 km southward its current main channel. Smooth undulated topography presenting low drainages density formed by sparse secondary plain channels and rounded lakes characterizes these deposits. Internally, they show point bars morphology constituted by intercalated layers of mud (silt and clay) and sand forming an inclined heterolithic stratification. The asymmetric distribution of fluvial terraces allied to the records of old scroll-bars features and paleochannels in many extensions of the Solimões River suggests the predominance of a meander pattern between 240 to 6 kyears. On the other hand, the development of the current anabranching pattern took place in the last six kyears due to the Holocene sea-level rise, besides the action of neotectonics and rainforest establishment related to the increase of humidity in Amazonia.