Horizon / Plein textes La base de ressources documentaires de l'IRD

IRD

 

Publications des scientifiques de l'IRD

Novello A., Lebatard A. E., Moussa A., Barboni D., Sylvestre Florence, Bourles D. L., Pailles C., Buchet G., Decarreau A., Duringer P., Ghienne J. F., Maley Jean, Mazur J. C., Roquin C., Schuster M., Vignaud P. (2015). Diatom, phytolith, and pollen records from a Be-10/Be-9 dated lacustrine succession in the Chad basin : insight on the Miocene-Pliocene paleoenvironmental changes in Central Africa. Palaeogeography Palaeoclimatology Palaeoecology, 430, 85-103 + corrigendum, 2016, 442, p. 128. ISSN 0031-0182

Accès réservé (Intranet IRD) Demander le PDF

Lien direct chez l'éditeur doi:10.1016/j.palaeo.2015.04.013

En Libre Accès sur HAL https://hal.archives-ouvertes.fr/hal-01691621

Titre
Diatom, phytolith, and pollen records from a Be-10/Be-9 dated lacustrine succession in the Chad basin : insight on the Miocene-Pliocene paleoenvironmental changes in Central Africa
Année de publication2015
Type de documentArticle référencé dans le Web of Science WOS:000356739800007
AuteursNovello A., Lebatard A. E., Moussa A., Barboni D., Sylvestre Florence, Bourles D. L., Pailles C., Buchet G., Decarreau A., Duringer P., Ghienne J. F., Maley Jean, Mazur J. C., Roquin C., Schuster M., Vignaud P.
SourcePalaeogeography Palaeoclimatology Palaeoecology, 2015, 430, p. 85-103 + corrigendum, 2016, 442, p. 128. ISSN 0031-0182
RésuméA discontinuous 200 m-long borehole drilled in the Bol Archipelago (13 degrees N, Lake Chad) provided 25 samples, which were dated using the Be-10/Be-9 method and analyzed for their micro-biological content. The dating provided ages ranging from 63 +/- 0.1 to 2.6 +/- 0.1 Ma, a period contemporaneous with the Pliocene fossil localities located in the current Djurab desert of Chad (16-17 degrees N). Well-preserved diatom assemblages first occurred at 4.7 +/- 0.1 Ma and were dominated by the freshwater planktonic genera Aulacoseira and Stephanodiscus until the end of the Pliocene. This supports the recurrence of lacustrine conditions at Bol during all the Pliocene. The presence of pelite and argillaceous deposits in the core before 4.7 +/- 0.1 Ma, however, suggests that the lake settled earlier, at least since 6.3 +/- 0.1 Ma. The abundance of Afromontane pollen taxa at 4.2 +/- 0.1 Ma and the occurrence of trapeziform polylobate phytoliths throughout the sequence suggest significant vegetation inputs from the southern highlands, while the importance of kaolinite in the clay sediments indicates a water supply predominantly from the south during the Pliocene. Phytolith assemblages are all dominated by lobate grass silica short cells and by blocky and elongate types, which attest to the presence of herbaceous-dominated vegetation around Bol and/or in the southern drainage basin during the Pliocene. This result is also supported by the pollen assemblage described at 4.2 +/- 0.1 Ma, which shows highest affinity for the savanna biome. Moreover, low values for the Xerophytic grass phytolith index indicate the presence of humid-loving (mesophytic and aquatic) grass communities in this vegetation. At last, significant variations in the abundance of blocky and elongate phytoliths are indicative of local alternations of fully lacustrine and marshy conditions at Bo!. Particularly between 3.6 and 2.7 Ma, the abundance of silicified bulliform cells combined with the absence of diatoms support a significant lacustrine reduction at Bol favoring the increasing of local marshy vegetation.
Plan de classementGéologie et formations superficielles [064] ; Ecologie, systèmes aquatiques [036] ; Etudes, transformation, conservation du milieu naturel [082] ; Sciences du milieu [021]
Descr. géo.AFRIQUE CENTRALE ; SAHARA ; SAHEL ; TCHAD BASSIN
LocalisationFonds IRD [F B010064754]
Identifiant IRDfdi:010064754
Lien permanenthttp://www.documentation.ird.fr/hor/fdi:010064754

Export des données

Disponibilité des documents

Télechargment fichier PDF téléchargeable

Lien sur le Web lien chez l'éditeur

Accès réservé en accès réservé

HAL en libre accès sur HAL


Accès aux documents originaux :

Le FDI est labellisé CollEx

Accès direct

Bureau du chercheur

Site de la documentation

Espace intranet IST (accès réservé)

Suivi des publications IRD (accès réservé)

Mentions légales

Services Horizon

Poser une question

Consulter l'aide en ligne

Déposer une publication (accès réservé)

S'abonner au flux RSS

Voir les tableaux chronologiques et thématiques

Centres de documentation

Bondy

Montpellier (centre IRD)

Montpellier (MSE)

Cayenne

Nouméa

Papeete

Abidjan

Dakar

Niamey

Ouagadougou

Tunis

La Paz

Quito