ISSN:
1573-8590
Keywords:
Bolivia
;
diatom
;
Late Glacial
;
paleohydrology
;
paleosalinity
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geography
Notes:
Abstract This study is focused on the endorheic Uyni-Coipasa Basin located in the southern Bolivian Altiplano. Stratigraphical and fossil diatom studies based on a detailed radiocarbon chrnology 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 mesosaline flora. Between ∼14,500 years and ∼13,000 years, finely lanminated 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 reached ∼+100 m). After ∼12,000 years, 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, characterized 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 teh available data on the northern (Lake Titicaca) and southern (Lipez are) Bolivian Altiplano and on the northern Chilean Altiplano (Atacama Desert).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01999113
Permalink
