The Holocene alluvial
plain of the middle
Geomorphology, Volume
44, Issues 3-4,
Edgardo M. Latrubesse and
Elena Franzinelli
Summary of Points:
·
The fluvial belt of the
·
In the study area the main channel of the Solimões
is nearly straight. The river may be considered anastomosed,
albeit with few islands and anabranches. The main Holocene units are the
impeded floodplain and the channel-dominated floodplain. The channel-dominated
floodplain is a complex mosaic of fluvial forms, including younger channels,
active sandbars, islands, levees, scroll-dominated plains, and abandoned belts.
·
The impeded floodplain is a widespread unit characterized by a
very flat surface and round or irregularly shaped lakes. The impeded drainage
flood plain is only partially affected by the present floods, and even those
parts affected by floods receive little or no sediment from the main channel.
·
More important sediment contribution is by alluvial plain channels
from the Solimões branches that generate deltas in
the impeded floodplain lakes. The impeded floodplain is interpreted to be an
earlier stage in the evolution of the Holocene alluvial belt. The formation was
marked by widespread vertical accretion and a channel morphogenetically
less active than at present. The later stage is associated with an active main
channel and the paranás, and generation of a
scroll-dominated plain.
·
This very large river system had a complex and delayed response to
variations in the hydrological conditions induced by changes in the regional
climate during the Late Holocene.
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