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Hydrodynamics in Holocene Lake Mega-Chad

Published online by Cambridge University Press:  20 January 2017

Frédéric Bouchette*
Affiliation:
GEOSCIENCES-M, Université Montpellier II et CNRS, cc 60, Place Eugène Bataillon, 34095 Montpellier cedex 5, France Institut de Mathématiques et modélisation de Montpellier, Université Montpellier II et CNRS, cc 51, Place Eugène Bataillon, 34095 Montpellier cedex 5, France
Mathieu Schuster
Affiliation:
Université de Poitiers UFR SFA, IPHEP - Institut International de Paléoprimatologie, Paléontologie Humaine: Evolution et Paléoenvironnements, CNRS UMR 6046, 40 avenue du Recteur Pineau, 86022 Poitiers, France
Jean-François Ghienne
Affiliation:
Institut de Physique du Globe de Strasbourg (CNRS/Université de Strasbourg, UMR 7516, EOST), 1, rue Blessig, 67084 Strasbourg, France
Cléa Denamiel
Affiliation:
HR-Wallingford, Howbery Park, Wallingford, OX10 8BA, UK
Claude Roquin
Affiliation:
Institut de Physique du Globe de Strasbourg (CNRS/Université de Strasbourg, UMR 7516, EOST), 1, rue Blessig, 67084 Strasbourg, France
Abderamane Moussa
Affiliation:
Université de Poitiers UFR SFA, IPHEP - Institut International de Paléoprimatologie, Paléontologie Humaine: Evolution et Paléoenvironnements, CNRS UMR 6046, 40 avenue du Recteur Pineau, 86022 Poitiers, France Institut de Physique du Globe de Strasbourg (CNRS/Université de Strasbourg, UMR 7516, EOST), 1, rue Blessig, 67084 Strasbourg, France
Patrick Marsaleix
Affiliation:
Laboratoire d'Aérologie-CNRS et Université de Toulouse, 14, Avenue Edouard Belin, 31400 Toulouse, France
Philippe Duringer
Affiliation:
Institut de Physique du Globe de Strasbourg (CNRS/Université de Strasbourg, UMR 7516, EOST), 1, rue Blessig, 67084 Strasbourg, France
*
*Corresponding author.E-mail addresses:[email protected] (F. Bouchette), [email protected] (M. Schuster).

Abstract

Holocene Lake Mega-Chad (LMC) was the largest late Quaternary water-body in Africa. The development of this giant paleo-lake is related to a northward shift of the isohyetes interpreted as evidence for an enhanced Monsoon (African Humid Period). Numerous preserved coastal features have been described all around the LMC shore. Such features reveal the main paleo-hydrodynamical tendencies. In the context of a closed water-body like LMC, hydrodynamics are forced mainly by winds. We use a three-dimensional numerical model (SYMPHONIE) to simulate the mean hydrodynamics in LMC under both Harmattan-like (northeasterly trade winds) and Monsoon-like (southwesterly winds) forcings. The northern part of LMC displays coastal features, such as sand spits, that are consistent with the simulations forced by Harmattan-like winds. Geomorphic features related to Monsoon-driven hydrodynamics are not clearly expressed. They could have developed during the early stage of LMC but subsequently reworked. At the time of sand-spit building, Harmattan-like driven hydrodynamics prevailed and related coastal features were preferentially preserved in the sedimentary record.

Type
Original Articles
Copyright
University of Washington

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