Sylvestre Florence, Servant Vildary Simone, Fournier Marc, Servant Michel. (1996). Lake levels in the southern Bolivian Altiplano (19°-21°S) during the Late Glacial based on diatom studies. International Journal of Salt Lake Research, 4, p. 281-300.
Titre du document
Lake levels in the southern Bolivian Altiplano (19°-21°S) during the Late Glacial based on diatom studies
Année de publication
1996
Auteurs
Sylvestre Florence, Servant Vildary Simone, Fournier Marc, Servant Michel
Source
International Journal of Salt Lake Research, 1996,
4, p. 281-300
This study is focused on the endorheic Uyuni-Coipasa Basin located in the southern Bolivian Altiplano. Stratigraphical and fossil diatom studies based on a detailed radiocarbon chronology revealed six phases in water-level changes and paleosalinity variations. At 15,430 +- 80 yr B.P., lacustrine conditions settled in the southern Bolivian Altiplano. A saline lake, characterized by benthic meso-metasaline species, reached +4 m altitude above the present bottom of the basin. After 15,430 +- 80 yr B.P. the level rapidly rose to + 27 m, as suggested by a tychoplanktonic mesoline flora. Between 14,500 years and 13,000 years, finely lamited sediments at + 32 m contained successively a dominance of epiphytic mesosaline to hypersaline species and tychoplanktonic oligosaline diatoms, indicating weak fluctuations in water-level and salinity. At 13,000 years, strong changes in the diatom flora occurred: epiphytic oligo-hypersaline diatoms were replaced by planktonic meso-polysaline species. They indicate a deep salt lake (the lake level reached + 100 m). After 12,j000 yars, the lake level abruptly dropped, as suggested by fluviatile sediments with a benthic mesopolysaline diatom flora. The main lake was replaced by shallow saline ponds. A wet pulse occurred at 11,400 years, characterizad by low water level ( + 7 m) and high salinity. This lacustrine phase remained until 10,400 yr B.P. These data indicate changes in Precipitation minus Evaporation (P-E). Our regional interpretations are based on a comparison with the available data on the northern (Lake Titicaca) and southern (Lipez area) Bolivian Altiplano and on the northern Chilean Altiplano (Atacama Desert). (Résumé d'auteur).
Plan de classement
Géologie du quaternaire [064GEOQUA]
Descripteurs
FLORE ; DIATOMEE ; FOSSILE ; STRATIGRAPHIE ; PALEOCLIMAT ; NIVEAU DE L'EAU ; SALINITE ; SEDIMENTATION GLACIAIRE ; SEDIMENTATION FLUVIATILE ; MILIEU LACUSTRE
Description Géographique
BOLIVIE ; ANDES
Localisation
Fonds IRD [F B010025538] ;
La Paz
Identifiant IRD
fdi:010025538
