Premium
Les Diatomées des Sédiments Holocènes du Bassin du Lac Afrera (Giulietti) (Afar Septentrional, Ethiopie). Essai de Reconstitution de l'Évolution du Milieu
Author(s) -
Gasse Françoise
Publication year - 1974
Publication title -
internationale revue der gesamten hydrobiologie und hydrographie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 52
eISSN - 1522-2632
pISSN - 0020-9309
DOI - 10.1002/iroh.19740590112
Subject(s) - holocene , diatom , geology , period (music) , structural basin , salinity , oceanography , quaternary , sedimentation , abundance (ecology) , eutrophication , ecology , physical geography , paleontology , geography , sediment , biology , physics , nutrient , acoustics
The calcareous holocene sediments found in the outlying areas around Lake Afrera (Ethiopia) contain diatoms in abundance, some of which seem to be new species. Qualitative and quantitative studies, with informatory treatment of the data, allow us to reconstruct the main characteristics of the sedimentation conditions and their variations in the course of time. During periods of warm and humid climatic conditions, the basin was progressively filled up with alkaline, lightly saline and quickly eutrophic water. At this time, the lake covered an area of 250 km 2 . This period occurred from 9800 years B. P. to around 7800 years B. P. It was followed by a short interruption, showed by important modifications in the diatom flora and a marked increase in the depth and salinity of the water. It has been hypothesized that this phenomenon had a tectonic origin. Soon thereafter, the previous ecological conditions reappeared. In the following period the lake began to dry up and the diatoms began to disappear. The present‐day highly saline Lake Afrera is all that remains of this large holocene water area. Diatoms of the Holocene Sediments in the Afrera Lake Basin. (Northern Afar, Ethiopia). Reconstruction of the Environmental Evolution