Fluvial sand, Amazon mud, and sediment accommodation in the tropical Maroni River estuary: Controls on the transition from estuary to delta and chenier plain

Type Article
Date 2021-01
Language English
Author(s) Gardel Antoine1, Anthony Edward J.1, 2, F. Dos Santos Valdenira3, Huybrechts Nicolas4, Lesourd Sandric5, Sottolichio Aldo6, Maury Tanguy1, Jolivet Morgane1
Affiliation(s) 1 : URS 3456 LEEISA, CNRS, University of Guyane, IFREMER, Cayenne, French Guiana
2 : Aix Marseille Univ, CNRS, IRD, INRA, Coll France, CEREGE, Aix-en-Provence, France
3 : NuPAq, IEPA, Mascara, Brazil
4 : Cerema, HA Research Team, 134 rue de Beauvais – CS 60039-60280 Margny-lès-Compiègne, France
5 : University of Caen Basse Normandie, UMR 6143 M2C, Caen, France
6 : University of Bordeaux, UMR 5805 EPOC, Bordeaux, France
Source Regional Studies In Marine Science (2352-4855) (Elsevier BV), 2021-01 , Vol. 41 , P. 101548 (11p.)
DOI 10.1016/j.rsma.2020.101548
WOS© Times Cited 8
Keyword(s) Tropical estuary, Delta, Chenier plain, Maroni river, Amazon mud

The Maroni River, South America, is a tropical estuary encased in a narrow lower valley with a limited area of estuarine tidal flat development, and displays a channel with large downstream-migrating sandy bedforms linked to a large sand-filled shallow mouth. The sand-rich nature of the lower Maroni River reflects significant fluvial bedload supply, and the Maroni is among rivers with the lowest suspension-sized sediment load in the world. During the dry season, the estuary shows high suspended sediment concentrations near the bottom (several g/l) that are due to the ingress of mud streaming alongshore from the Amazon River delta. However, Amazon mud is expelled from the estuary during the high-discharge rainy-season, and seems to be essentially restricted to this seasonal intrusion along the main channel with little net estuarine sedimentation because of limited channel overbank sediment accommodation space. Sand actively supplied by the Maroni River to the coast has been diverted by wave-generated longshore transport westwards, towards the Suriname coast. This has resulted in the construction of numerous sandy cheniers within a muddy coastal plain built from Amazon mud. This sediment-source dichotomy is an important original feature of the Guiana Shield estuaries. The asymmetric progradation at the mouth of the Maroni fingerprints the westward growth, in the vicinity of river mouths, of the muddy, chenier-studded, coastal plain of the Guianas. The propensity for these rivers to supply sand to the coast, eventually evolving into deltas, depends on the ability of their estuaries to limit westward (downdrift) deflection by long-term updrift coastal sedimentation. The Maroni estuary has tended to evolve towards a delta built from both Maroni river sand and Amazon mud, a stage, among the Guiana Shield Rivers, that only the large Essequibo River estuary in Guyana has achieved. Further studies will be needed in order to constrain the infill pattern of the Maroni River estuary and its mouth.

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Gardel Antoine, Anthony Edward J., F. Dos Santos Valdenira, Huybrechts Nicolas, Lesourd Sandric, Sottolichio Aldo, Maury Tanguy, Jolivet Morgane (2021). Fluvial sand, Amazon mud, and sediment accommodation in the tropical Maroni River estuary: Controls on the transition from estuary to delta and chenier plain. Regional Studies In Marine Science, 41, 101548 (11p.). Publisher's official version : https://doi.org/10.1016/j.rsma.2020.101548 , Open Access version : https://archimer.ifremer.fr/doc/00663/77505/