Lake-Level Chronology on the Southern Bolivian Altiplano (18°–23°S) During Late-Glacial Time and the Early Holocene

Abstract

Stratigraphic analyses of outcrops, shorelines, and diatoms from the southern Bolivian Altiplano (Uyuni-Coipasa basin) reveal two major lacustrine phases during the late-glacial period and the early Holocene, based on a chronology established by radiocarbon and U/Th control. A comparison of14C and230Th/234U ages shows that during times of high lake level, radiocarbon ages are valid. However, during low-water periods,14C ages must be corrected for a reservoir effect. The lacustrine Tauca phase started a little before 16,00014C yr B.P., and the lake level reached its maximum between 13,000 and 12,00014C yr B.P. A dry event (Ticaña) occurred after ca. 12,000 and before 950014C yr B.P. A moderate lacustrine oscillation (Coipasa event) occurred between ca. 9500 and 850014C yr B.P., using a reservoir-corrected conventional14C chronology. Comparisons between the lake-level chronology in the Uyuni-Coipasa basin and data from other southern tropical areas of South America suggest that the lacustrine evolution may reflect large-scale climatic changes.

The Geology of Mars

“…Smaller stromatolites located stratigraphically closer to the current shore are dated 11 210 ± 120 years. These results are consistent with the large paleolake being formed during the Holocene wet climate episode (Messerli et al, 1993;Wirrmann and Mourguiart, 1995;Grosjean et al, 1995;Baucom and Rigsby, 1999;Sylvestre et al, 1999;Vuille et al, 2003). Below this stratigraphic level, and closer to the current active shoreline, the density of fossil structures is scarce.…”

“…These analyses also contribute to the understanding of the hydrological and algological state of the Andean high lakes (Hustedt, 1927;Rumrich et al, 2000). Several Bolivian lower lakes (mostly in the Unuyi region) were investigated as tracers of modern climate changes (Sylvestre et al, 1999;Servant Vilardy et al, 2000).…”

Late Quaternary Climate and Hydrology of Tropical South America Inferred from an Isotopic and Chemical Model of Lake Titicaca, Bolivia and Peru

“…Ancient shorelines, marked by carbonate bioherm deposits on the central Altiplano, show that the most recent paleolake, known as Lake Tauca, covered about 60,000 km 2 and obtained depths greater than 100 m (Bills et al, 1994;Blodgett et al, 1997;Sylvestre et al, 1999). The Tauca lacustrine phase (including the subsequent, smaller Coipasa phase) lasted from about 25,000 cal yr B.P.…”

“…to about 12,000 cal yr B.P. (Servant et al, 1995;Sylvestre et al, 1999;Baker et al, 1999). Prior to the Tauca phase, wet and dry conditions alternated on the Altiplano for at least a few hundred thousand years (Servant and Fontes, 1978;Seltzer et al, 1999;Baker et al, 1999).…”

Signatures of habitats and life in Earth's high-altitude lakes: clues to Noachian aqueous environments on Mars

“…Most of the brackish lagunas in the Bolivian Altiplano were formed as freshwater lakes and experienced their peak volumes during the early Holocene between 18 000 and 9200 BP, when precipitation reached 400À500 mm/yr (Tauca phase, Messerli et al, 1993;Wirrmann and Mourguiart, 1995;Grosjean et al, 1995;Baucom and Rigsby, 1999;Sylvestre et al, 1999;Vuille et al, 2003). Our topographic survey using Global Positioning System (GPS) and Laser Range Finder shows that the two lagunas were originally one large ($20 Â 3 km), deep ($55 m) lake which has receded significantly since its formation.…”