Origin and function of a closed depression in equatorial humid zones : the lake Télé in north Congo

1998

Article

Laraque Alain, Pouyaud Bernard, Rocchia R., Robin E., Chaffaut Isabelle, Moutsambote J.M., Maziezoula B., Censier C., Albouy Yves, Elenga H., Etcheber H., Delaune Mireille, Sondag Francis, Gasse F.

Journal of Hydrology, 1998, 207, p. 236-253 ISSN 0022-1694

Lake Télé has a nearly perfect ellipsoidal shape and is surrounded by swamps and barely penetrable flooded forests in the heart of the Congo-Zaïre watershed basin, and has intrigued the international scientific community for decades. In June 1992, a first Franco-Congolese multidisciplinary scientific expedition was finally able to reach the lake which is vast (23 km2) and shallow (3 m). Its volume is estimated at 71 000 000 m3 and is 40% filled with an organic silt layer a metre thick. Its hydrological exchanges are almost exclusively vertical with very little lateral contribution from the surrounding swamp. This leads to the observation that the waters are very slightly mineralized (< 3 mg/l), but are very rich in organic carbon (44% of suspended matter and of total dissolved matter) and are very acidic (pH < 4). In addition, a magnetic anomaly of some hundred nanoTesla from a magnetic body at shallow depth has been detected in the lake's northern half, although its origin remains unknown. Botanical and palynological observations suggest the persistence of a strongly hydromorphic forest environment for at least the last 6600 years. Identified pollen taxa, whether ancient or recent, come mainly from pioneer and colonizing taxa such as Macaranga, which tends to indicate that the forest is continuing to gradually fill in the lake. (Résumé d'auteur)

Milieux physico-chimique [032MILPHY]

MILIEU LACUSTRE ; PALEOHYDROLOGIE ; GEOMORPHOLOGIE ; LIMNOLOGIE ; CHIMIE DE L'EAU ; ANOMALIE MAGNETIQUE ; PALEOENVIRONNEMENT ; FORET ; PALYNOLOGIE

CONGO

Fonds IRD [F B010014857] ; Montpellier (Centre IRD)

fdi:010014857