Sajsi

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Sajsi is the name of an ancient lake in the Andes

The existence of ancient lakes in the Altiplano was proposed as early as 1882. At first, a Lake Minchin was identified with ages of 30,000 years or older; later additional lake cycles were recognized. [1] The minor ones include Inca Huasi, Salinas and Coipasa. The major ones include Lake Tauca and Ouki. [2] Because of this, it was proposed that Lake Minchin was actually a combination of several different ancient lakes. [3]

This lake occupied the area of the current Salar de Uyuni; [4] it also covered the Salar de Coipasa but it is not clear whether and how it extended in the Lake Poopo. [5] Its waters reached altitudes of 3,670 metres (12,040 ft) and its depth did not exceed 17 metres (56 ft). [6] A sample dated 23,700 ± 2,600 years ago by uranium-thorium dating indicates that lake levels at that point were about 15 metres (49 ft) deep in the Uyuni basin. [7] Water levels subsequently decreased to less than 5 metres (16 ft) above the present day levels before Lake Tauca formed, [8] however both the timing and the history of water levels are uncertain. [9] The surface area of the lake may have been 21,000 square kilometres (8,100 sq mi) during the highstand. [10] By 19,900 ± 900 - 18,700 ± 200 years ago, the Lake Tauca was beginning to form. [7] The so-called "L2" unit in drill cores in Salar de Uyuni may correspond to both the Sajsi and the later Lake Tauca cycle. [11] Strontium isotope data indicate that about 41% of the water in Sajsi came from Lake Poopo and 4% from Lake Titicaca. [12]

Radiocarbon dates have been obtained for Sajsi-age ooids and tufa, uncalibrated they range from 17,080 ± 720 to 20,830 ± 140 years ago. [13] Later dates indicated that the lake existed between 25,000 and 19,000 years ago and reached its maximum depth 23,000 years ago. [7] The existence of this lake coincides with the Last Glacial Maximum. Earlier, lakes had formed in the Laguna Blanca, the Salar de Atacama, [4] as well as the Pozuelos Basin in northwest Argentina. [14] Given evidence from the Bolivian Eastern Cordillera [15] and the small size of the glacial Sajsi and Inca Huasi paleolakes, it is likely that the Last Glacial Maximum was accompanied by a dry climate on the Altiplano [8] and indeed climate modelling shows that only a small precipitation increase - or none at all - would be needed to create the Sajsi lake. [16] Glacier expansion is recorded at that time in Northwest Argentina. [17] The second Heinrich event seems to coincide with the Sajsi lake period. [18]

A maximum in local insolation about 21,000 years ago coincides with the existence of the Sajsi lake but was probably not responsible for the lake's existence. [19] Farther south, precipitation in the drainage area of the Rio Salado had increased by 10 millimetres per year (0.39 in/year) during the Sajsi time, [20] lakes formed within the Western Cordillera [21] and the Bolivian Chaco likewise shows evidence of increased precipitation. [22] Rising water levels during the Sajsi reduced dust deflation. [23] The Sajsi lake was apparently followed by Lake Tauca, but evidence is lacking. [24] Another theory postulates that Sajsi was simply a sub-phase of Lake Tauca, [25] an interpretation applied in particular to data taken from drill cores. [26]

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References

  1. ↑ Sánchez-Saldías, Andrea; Fariña, Richard A. (March 2014). "Palaeogeographic reconstruction of Minchin palaeolake system, South America: The influence of astronomical forcing". Geoscience Frontiers. 5 (2): 250. doi: 10.1016/j.gsf.2013.06.004 .
  2. ↑ Placzek, Quade & Patchett 2006, p. 520.
  3. ↑ Placzek, Quade & Patchett 2006, p. 528.
  4. 1 2 Torres, Gonzalo R.; Lupo, Liliana C.; Kulemeyer, Julio J.; Pérez, Claudio F. (May 2016). "Palynological evidence of the geoecological belts dynamics from Eastern Cordillera of NW Argentina (23° S) during the Pre-Last Glacial Maximum". Andean Geology . 24 (2): 151. doi: 10.5027/andgeoV43n2-a01 . hdl: 11336/55881 . ISSN   0718-7106 . Retrieved 9 October 2016.
  5. ↑ Placzek, Quade & Patchett 2013, p. 102.
  6. ↑ Placzek, Quade & Patchett 2006, p. 524.
  7. 1 2 3 Blard et al. 2011, p. 3984.
  8. 1 2 Placzek, Quade & Patchett 2006, p. 531.
  9. ↑ Blard et al. 2011, p. 3974.
  10. ↑ Placzek, Quade & Patchett 2013, p. 103.
  11. ↑ Placzek, Quade & Patchett 2006, p. 529.
  12. ↑ Placzek, Christa J.; Quade, Jay; Patchett, P. Jonathan (January 2011). "Isotopic tracers of paleohydrologic change in large lakes of the Bolivian Altiplano" (PDF). Quaternary Research. 75 (1): 239. Bibcode:2011QuRes..75..231P. doi:10.1016/j.yqres.2010.08.004. S2CID   54069269.
  13. ↑ Placzek, Quade & Patchett 2006, p. 519.
  14. ↑ McGlue et al. 2013, p. 653.
  15. ↑ Ratnayaka, Kevin; Hetzel, Ralf; Hornung, Jens; Hampel, Andrea; Hinderer, Matthias; Frechen, Manfred (2019). "Postglacial alluvial fan dynamics in the Cordillera Oriental, Peru, and palaeoclimatic implications". Quaternary Research. 91 (1): 16. doi:10.1017/qua.2018.106. ISSN   0033-5894. S2CID   134229798.
  16. ↑ Vargo, L.J.; Galewsky, J.; Rupper, S.; Ward, D.J. (April 2018). "Sensitivity of glaciation in the arid subtropical Andes to changes in temperature, precipitation, and solar radiation". Global and Planetary Change. 163: 87. doi: 10.1016/j.gloplacha.2018.02.006 . ISSN   0921-8181.
  17. ↑ Zech, Jana; Zech, Roland; Kubik, Peter W.; Veit, Heinz (December 2009). "Glacier and climate reconstruction at Tres Lagunas, NW Argentina, based on 10Be surface exposure dating and lake sediment analyses". Palaeogeography, Palaeoclimatology, Palaeoecology. 284 (3–4): 180. Bibcode:2009PPP...284..180Z. doi:10.1016/j.palaeo.2009.09.023.
  18. ↑ Placzek, Quade & Patchett 2013, p. 106.
  19. ↑ Quade, Jay; Rech, Jason A.; Betancourt, Julio L.; Latorre, Claudio; Quade, Barbra; Rylander, Kate Aasen; Fisher, Timothy (May 2008). "Paleowetlands and regional climate change in the central Atacama Desert, northern Chile". Quaternary Research. 69 (3): 358. doi:10.1016/j.yqres.2008.01.003. S2CID   121189411.
  20. ↑ Latorre, Claudio; Betancourt, Julio L.; Arroyo, Mary T.K. (May 2006). "Late Quaternary vegetation and climate history of a perennial river canyon in the Río Salado basin (22°S) of Northern Chile". Quaternary Research. 65 (3): 462. Bibcode:2006QuRes..65..450L. doi:10.1016/j.yqres.2006.02.002. hdl: 10533/178091 . S2CID   129119233.
  21. ↑ Pfeiffer, Marco; Latorre, Claudio; Santoro, Calogero M.; Gayo, Eugenia M.; Rojas, Rodrigo; Carrevedo, María Laura; McRostie, Virginia B.; Finstad, Kari M.; Heimsath, Arjun; Jungers, Matthew C.; De Pol-Holz, Ricardo; Amundson, Ronald (October 2018). "Chronology, stratigraphy and hydrological modelling of extensive wetlands and paleolakes in the hyperarid core of the Atacama Desert during the late quaternary". Quaternary Science Reviews. 197: 237. doi:10.1016/j.quascirev.2018.08.001. ISSN   0277-3791. OSTI   1830486. S2CID   134817135.
  22. ↑ May, Jan-Hendrik; Zech, Roland; Veit, Heinz (June 2008). "Late Quaternary paleosol–sediment-sequences and landscape evolution along the Andean piedmont, Bolivian Chaco". Geomorphology. 98 (1–2): 47. Bibcode:2008Geomo..98...34M. doi:10.1016/j.geomorph.2007.02.025.
  23. ↑ Vanderstraeten, Aubry; Mattielli, Nadine; Laruelle, Goulven G.; Gili, Stefania; Bory, Aloys; Gabrielli, Paolo; Boxho, Sibylle; Tison, Jean-Louis; Bonneville, Steeve (July 2023). "Identifying the provenance and quantifying the contribution of dust sources in EPICA Dronning Maud Land ice core (Antarctica) over the last deglaciation (7–27 kyr BP): A high-resolution, quantitative record from a new Rare Earth Element mixing model". Science of The Total Environment. 881: 163450. doi:10.1016/j.scitotenv.2023.163450.
  24. ↑ Broecker, Wally; Putnam, Aaron E. (December 2012). "How did the hydrologic cycle respond to the two-phase mystery interval?". Quaternary Science Reviews. 57: 20. Bibcode:2012QSRv...57...17B. doi:10.1016/j.quascirev.2012.09.024.
  25. ↑ McPhillips, Devin; Bierman, Paul R.; Crocker, Thomas; Rood, Dylan H. (December 2013). "Landscape response to Pleistocene-Holocene precipitation change in the Western Cordillera, Peru: Be concentrations in modern sediments and terrace fills" (PDF). Journal of Geophysical Research: Earth Surface. 118 (4): 2490. Bibcode:2013JGRF..118.2488M. doi: 10.1002/2013JF002837 . hdl:10044/1/40590.
  26. ↑ McGlue et al. 2013, p. 652.

Sources

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  • McGlue, Michael M.; Cohen, Andrew S.; Ellis, Geoffrey S.; Kowler, Andrew L. (December 2013). "Late Quaternary stratigraphy, sedimentology and geochemistry of an underfilled lake basin in the Puna plateau (northwest Argentina)". Basin Research. 25 (6): 638–658. doi:10.1111/bre.12025. S2CID   16055852.
  • Placzek, C.; Quade, J.; Patchett, P. J. (8 May 2006). "Geochronology and stratigraphy of late Pleistocene lake cycles on the southern Bolivian Altiplano: Implications for causes of tropical climate change". Geological Society of America Bulletin. 118 (5–6): 515–532. Bibcode:2006GSAB..118..515P. doi:10.1130/B25770.1.
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