Lake Tauca
| Lake Tauca | |
|---|---|
| Lake Pocoyu | |
Satellite image of the Altiplano. The green, brown and white surfaces in the lower right quadrant of the image are Lake Poopó, Salar de Coipasa and Salar de Uyuni, respectively. The blue surface at centre top is Lake Titicaca | |
Lake Tauca | |
| Location | Andes, South America |
| Coordinates | 20°S 68°W / 20°S 68°W |
| Type | Former lake Pleisto- Holocene glacial lake 72,600–7200 BP |
| Part of | Altiplano |
| Primary inflows | Glacial meltwater Desaguadero River, Río Grande de Lipez, Lauca River |
| Primary outflows | Potentially Pilcomayo River |
| Basin countries | Bolivia, Chile, Peru |
| Surface area | 48,000–80,000 km2 (19,000–31,000 sq mi) |
| Average depth | 100 m (330 ft) |
| Max. depth | 142 m (466 ft) |
| Water volume | 1,200–3,810 km3 (290–910 cu mi) |
| Salinity | 20–90 g/L (0.00072–0.00325 lb/cu in) |
| Surface elevation | 3,660–3,770 m (12,010–12,370 ft) |
| Max. temperature | 10 °C (50 °F) |
| Min. temperature | 2 °C (36 °F) |
Lake Tauca is a former lake in the Altiplano of Bolivia. It is also known as Lake Pocoyu for its constituent lakes: Lake Poopó, Salar de Coipasa and Salar de Uyuni. At high water levels, the lake spread across the southern Altiplano between the Eastern and Western Cordilleras, flooding the basins that now hold Lake Poopó and the Uyuni and Coipasa salars. Published area estimates range from about 48,000 to 80,000 square kilometres (19,000 to 31,000 sq mi). Water levels varied, possibly reaching about 3,800 metres (12,500 ft) above sea level. It was a saline lake. The lake received water from Lake Titicaca, although estimates of Titicaca's contribution vary widely. In any case, Tauca was large enough to influence local climate and to depress the underlying terrain under its own weight. Diatoms, plants and animals lived in the lake, sometimes forming reef-like carbonate knolls.
The duration of Lake Tauca's existence is uncertain. Research published in 2011 suggested that lake levels began rising around 18,500 BP and reached their main highstand around 16,000–14,500 years ago. Around 14,200 years ago, lake levels fell, then rose again and persisted until about 11,500 years ago. Some researchers suggest that the final phase may have continued until about 8,500 BP. When the lake dried—possibly during the Bølling–Allerød oscillation—it left the salt deposits of Salar de Uyuni.
Lake Tauca is one of several ancient lakes which formed in the Altiplano. Lake Tauca was one of several named Altiplano palaeolakes (including Escara, Ouki, Salinas, Minchin, Inca Huasi and Sajsi), alongside repeated highstands of Lake Titicaca. How these named lake phases relate to one another is debated. Sajsi is often treated as part of the Tauca system, and Tauca itself is frequently divided into an earlier Ticaña phase and a later Coipasa phase.
Lake Tauca formed when the Altiplano became colder and wetter, likely because shifts in the Intertropical Convergence Zone (ITCZ) strengthened easterly moisture transport. Early explanations emphasised glacial meltwater, but melt alone would not have provided enough water to fill the lake. Glaciers advanced alongside the lake, leaving clear evidence at Cerro Azanaques and Tunupa. Elsewhere in South America, water levels and glaciers also expanded during the Lake Tauca phase.