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Title: The impact of Quaternary sea level changes on the evolution of the Amazonian lowland
Authors: Irion, George F.
Müller, Jens
Morais, Jáder Onofre de
Keim, Gertrud
Mello, Jose Nunes de
Junk, Wolfgang Johannes
Keywords: Erosion
Sea Level
Sediment Transport
Water Levels
Backwater Effects
Bed-load Transport
Last Glacial Maximum
Quaternary (late)
Rivers And Lakes
Sealevel Change
Landform Evolution
Lowland Environment
Sealevel Change
Sediment Transport
Amazon River
South America
Issue Date: 2009
metadata.dc.publisher.journal: Hydrological Processes
metadata.dc.relation.ispartof: Volume 23, Número 22, Pags. 3168-3172
Abstract: Coring and acoustic surveying (3.5 kHz) in both rivers and lakes in Central Amazonia provide additional insights into the Late Quaternary hydrological and sedimentological development of the Amazon River and its tributaries. Erosion and accumulation phases were found to be linked to Quaternary sea level changes. The low sea level phase during the last glacial maximum caused deep incision of the Amazon River and erosion in major tributaries such as the Rio Negro, 1500 km upstream from the Amazon mouth. A 3.5-kHz profiling suggests a lowering of the water level by at least 30 m at Manaus. During that phase, the slope of the Amazon valley must have increased, resulting in an increase in bed load transport capacity. The subsequent sea level rise caused a backwater effect far upstream, with silting up of the Amazon valley and the tributary inflows. Former river systems changed into Ria lakes. The floodplains of the Amazon River, the várzea, were formed approximately 5000 years ago when the sea level approached its present-day level. Copyright © 2009 John Wiley & Sons, Ltd.
metadata.dc.identifier.doi: 10.1002/hyp.7386
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