Laguna Lejía is a salt lake located in the Altiplano of the Antofagasta Region of northern Chile. The landscape of the area is dominated by the volcanoes Chiliques, Lascar, Aguas Calientes and Acamarachi. It is shallow and has no outlet, covering a surface area of about 1.9 square kilometres (0.73 sq mi) in the present-day.
During glacial times, the lake was considerably larger owing to decreased evaporation and increased precipitation rates, with bioherms developing around the waterbody. Presently, flamingos and a number of microorganisms live in the lake.
Lejía Lake is a circular,[8] shallow lake[5] at an elevation of 4,325 metres (14,190 ft)[1] with a surface area of 1.9 square kilometres (0.73 sq mi)[5][1] or 2 square kilometres (0.77 sq mi). It is a polymictic lake which freezes over occasionally[9] and whose waters are turned over quickly,[10] mainly through evaporation.[11] Winds sometimes create foam on the lake surface and blow them onto the shores.[12] Water temperatures have been measured to range between 3–10.6 °C (37.4–51.1 °F), and the lake is about 1.2 metres (3 ft 11 in) deep.[13]
The lake is nourished from the north through two creeks, one originates on Aguas Calientes and the other from two tributaries on Lascar and Cerro del Abra. From Chiliques and Lejia in the south other creeks run north and enter the southern part of the lake.[8] A groundwater outlet appears to exist, considering that there is no halite accumulating in the lake,[17] and Cerro Overo is a maar that formed through groundwater-magma interaction.[18]
Lake history
The lake lies in a tectonic depression, which is geologically related to the fault system Miscanti-Callejón de Varela;[5] once it was thought that the lake was in a caldera.[12] The Altos de Toro Blanco mountains separate Lejía Lake's drainage basin from the Salar de Aguas Calientes catchment.[5] A lineament known as the Tumisa line runs along the southern shore of the lake,[7] and appears to have been the site of three earthquakes in post-glacial time.[19] The lake is influenced by volcanic activity from the neighbouring Lascar; ash and pyroclastic material entered Lejía Lake in 1993,[20] and the large Soncor eruption from this volcano 26,450 years before present filled the lake.[21]
During glacial times, the lake was considerably larger, reaching a surface area of 10 square kilometres (3.9 sq mi)[9] with water levels rising to about 25 metres (82 ft) above present-day level; the lake was filled with freshwater at that time.[22] A volcanic marker dated to 16,700 ± 2,000 years before present pre-dates the lake highstand;[23] this volcanic marker is a tephra erupted by the Cerro Corona lava dome south of Lascar.[24] Lake levels stayed high until the Holocene and then decreased; the timing of Holocene changes is unknown.[22] These earlier larger lakes have left terraces around Lejía Lake which contain bioherms and stromatolith leftovers.[20] Water level fluctuations drove changes in microbial ecosystems around the lake.[25] Even older deposits associated with the Lake Minchin wet period are not present at Lejía Lake unlike other Altiplanic lakes, probably owing to volcanic activity that disrupted the sediments.[21] The environment at Laguna Lejía has been used as analogues for ancient lakes on Mars like Jezero crater, which might have been habitable before they dried up.[26]
The increase in surface area was a consequence of increased precipitation and increased cloud cover which decreased its evaporation rate.[10]Sediment cores have shown evidence of separate lake stages with water levels mostly higher than today;[11] higher moisture levels owing to a displacement of the tropical circulation during the Lake Tauca stage have been invoked to explain higher lake levels in Lejía and other regional waterbodies.[27]Glaciers developed in the region as well but did not reach the lake.
[28]
Climate
Precipitation around the lake is about 200 millimetres per year (7.9 in/year) mostly during the summer months, considerably less than the annual evaporation rate. Temperatures range −6–7 °C (21–45 °F) with an average temperature of 2 °C (36 °F);[9] night temperatures can drop to −18 – −25 °C (0 – −13 °F).[29] There is strong daily and interannual variability of the weather.[30] During glacial highstands, precipitation was about double that of today.[31]
Archeological artifacts from the archaic period have been found on an upper terrace of the lake,[22] indicating that ancient hunters did head to Lejía Lake at that time.[38]
^ abcSimoneit, Bernd R. T.; Halpern, H. I.; Didyk, B. M. (1980). "Lipid Productivity of a High Andean Lake". Biogeochemistry of Ancient and Modern Environments. p. 201. doi:10.1007/978-3-662-26582-6_21. ISBN978-0-85847-062-0.
Grosjean, Martin (May 1994). "Paleohydrology of the Laguna Lejía (north Chilean Altiplano) and climatic implications for late-glacial times". Palaeogeography, Palaeoclimatology, Palaeoecology. 109 (1): 89–100. Bibcode:1994PPP...109...89G. doi:10.1016/0031-0182(94)90119-8. ISSN0031-0182.