Impact of Bolivian paleolake evaporation on the δ18O of the Andean glaciers during the last deglaciation (18.5-11.7 ka): Diatom-inferred δ18O values and hydro-isotopic modeling

Título traducido de la contribución: Impacto de la evaporación de los paleolagos bolivianos en el δ18O de los glaciares andinos durante la última deglaciación (18.5-11.7 ka): Valores de Diatomea-Inferida δ18O y modelación hidro-isotópica

Benjamin Quesada, Florence Sylvestre, Françoise Vimeux, Jessica Black, Christine Paillès, Corinne Sonzogni, Anne Alexandre, Pierre Henri Blard, Alain Tonetto, Jean Charles Mazur, Hélène Bruneton

Resultado de la investigación: Contribución a RevistaArtículo

5 Citas (Scopus)

Resumen

Durante la última deglaciación, el Altiplano boliviano (15-23°S, 66-70°O) fue ocupado por el paleolago Tauca, cubriendo, como mínimo, unos 51.000 km2 en su máxima altitud entre 16,5 y 15 ka. Dos mil quinientos años después, después de una regresión masiva, una nueva fase transgresora, produjo el paleolago Coipasa, más pequeño que Tauca y restringido a la parte sur de la cuenca. Estos paleolagos fueron vistos al oeste por la capa de hielo de Sajama. Este último proporciona un registro continuo de la composición isotópica de oxígeno de la paleoprecipitación para los últimos 25 ka. Contemporáneamente al final del paleolago Tauca, alrededor de 14.3 ka, la capa de hielo de Sajama registró un aumento significativo en la composición isotópica del oxígeno del hielo (δ18Oice). Este trabajo examina hasta qué punto la desaparición del lago Tauca contribuyó a la precipitación en la cumbre del Sajama y esta variación isotópica específica. Los valores del agua δ18O de los paleolagos Tauca y Coipasa (δ18Olake) fueron reconstruidos cuantitativamente de 18.5 a 11.7 ka en base a la composición isotópica de diatomeas (δ18Odiatoms) y la composición isotópica de ostracodas (δ18Ocarbonates) recuperadas en sedimentos lacustres. A una escala temporal centenaria, aparece una fuerte tendencia: las disminuciones abruptas de δ18Olake durante los rellenos del lago son seguidas inmediatamente por aumentos abruptos de δ18Olake durante las fases estables del nivel del lago. La variación más alta ocurrió en ~15.8 ka con una disminución de δ18Olake de aproximadamente ~10‰, concomitante con la altura del Lago Tauca, seguido de ~400 años más tarde por un aumento de 7‰ en δ18Olake. Un simple enfoque de modelación hidro-isotópica reproduce consistentemente esta característica de rápido "aumento de la disminución". Además, sugiere que este inesperado aumento en δ18Olake después de las fases de llenado puede explicarse en parte por un equilibrio de los flujos isotópicos durante el estado estacionario del lago. Basados en cálculos isotópicos durante la evaporación del lago y un simple balance de isótopos estables en el agua entre fuentes potenciales de humedad en Sajama (advección versus evaporación del lago), mostramos que la evaporación total o parcial (del 5 al 60%) de la Tauca paleolaca durante su fase de regresión mayor a 14.3 ka podría explicar la pronunciada excursión isotópica en la capa de hielo de Sajama. Estos resultados sugieren que las perturbaciones del ciclo hidrológico local en áreas lacustres pueden afectar sustancialmente la interpretación paleoclimática de las señales isotópicas cercanas (por ejemplo, núcleo de hielo o espeleotemas)

Idioma originalEnglish (US)
Páginas (desde-hasta)93-106
Número de páginas14
PublicaciónQuaternary Science Reviews
Volumen120
DOI
EstadoPublished - jul 5 2015
Publicado de forma externa

All Science Journal Classification (ASJC) codes

  • Global and Planetary Change
  • Ecology, Evolution, Behavior and Systematics
  • Archaeology
  • Archaeology
  • Geology

Citar esto

Quesada, Benjamin ; Sylvestre, Florence ; Vimeux, Françoise ; Black, Jessica ; Paillès, Christine ; Sonzogni, Corinne ; Alexandre, Anne ; Blard, Pierre Henri ; Tonetto, Alain ; Mazur, Jean Charles ; Bruneton, Hélène. / Impact of Bolivian paleolake evaporation on the δ18O of the Andean glaciers during the last deglaciation (18.5-11.7 ka) : Diatom-inferred δ18O values and hydro-isotopic modeling. En: Quaternary Science Reviews. 2015 ; Vol. 120. pp. 93-106.
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title = "Impact of Bolivian paleolake evaporation on the δ18O of the Andean glaciers during the last deglaciation (18.5-11.7 ka): Diatom-inferred δ18O values and hydro-isotopic modeling",
abstract = "During the last deglaciation, the Bolivian Altiplano (15-23°S, 66-70°W) was occupied by paleolake Tauca covering, at least, ~51,000 km2 at its maximum highstand between 16.5 and 15 ka. Twenty-five hundred years later, after a massive regression, a new transgressive phase, produced paleolake Coipasa, smaller than Tauca and restricted to the southern part of the basin. These paleolakes were overlooked at the west by the Sajama ice cap. The latter provides a continuous record of the oxygen isotopic composition of paleo-precipitation for the last 25 ka. Contemporaneously to the end of paleolake Tauca, around 14.3 ka, the Sajama ice cap recorded a significant increase in ice oxygen isotopic composition (δ18Oice). This paper examines to what extent the disappearance of Lake Tauca contributed to precipitation on the Sajama summit and this specific isotopic variation. The water δ18O values of paleolakes Tauca and Coipasa (δ18Olake) were quantitatively reconstructed from 18.5 to 11.7 ka based on diatom isotopic composition (δ18Odiatoms) and ostracod isotopic composition (δ18Ocarbonates) retrieved in lacustrine sediments. At a centennial time scale, a strong trend appears: abrupt decreases of δ18Olake during lake fillings are immediately followed by abrupt increases of δ18Olake during lake level stable phases. The highest variation occurred at ~15.8 ka with a δ18Olake decrease of about ~10‰, concomitant with the Lake Tauca highstand, followed ~400 years later by a 7‰ increase in δ18Olake. A simple hydro-isotopic modeling approach reproduces consistently this rapid {"}decrease-increase{"} feature. Moreover, it suggests that this unexpected re-increase in δ18Olake after filling phases can be partly explained by an equilibration of isotopic fluxes during the lake steady-state. Based on isotopic calculations during lake evaporation and a simple water stable isotopes balance between potential moisture sources at Sajama (advection versus lake evaporation), we show that total or partial evaporation (from 5 to 60{\%}) of paleolake Tauca during its major regression phase at 14.3 ka could explain the pronounced isotopic excursion at Sajama ice cap. These results suggest that perturbations of the local hydrological cycle in lacustrine areas may substantially affect the paleoclimatic interpretation of the near-by isotopic signals (e.g. ice core or speleothems).",
author = "Benjamin Quesada and Florence Sylvestre and Fran{\cc}oise Vimeux and Jessica Black and Christine Paill{\`e}s and Corinne Sonzogni and Anne Alexandre and Blard, {Pierre Henri} and Alain Tonetto and Mazur, {Jean Charles} and H{\'e}l{\`e}ne Bruneton",
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Impact of Bolivian paleolake evaporation on the δ18O of the Andean glaciers during the last deglaciation (18.5-11.7 ka) : Diatom-inferred δ18O values and hydro-isotopic modeling. / Quesada, Benjamin; Sylvestre, Florence; Vimeux, Françoise; Black, Jessica; Paillès, Christine; Sonzogni, Corinne; Alexandre, Anne; Blard, Pierre Henri; Tonetto, Alain; Mazur, Jean Charles; Bruneton, Hélène.

En: Quaternary Science Reviews, Vol. 120, 05.07.2015, p. 93-106.

Resultado de la investigación: Contribución a RevistaArtículo

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T1 - Impact of Bolivian paleolake evaporation on the δ18O of the Andean glaciers during the last deglaciation (18.5-11.7 ka)

T2 - Diatom-inferred δ18O values and hydro-isotopic modeling

AU - Quesada, Benjamin

AU - Sylvestre, Florence

AU - Vimeux, Françoise

AU - Black, Jessica

AU - Paillès, Christine

AU - Sonzogni, Corinne

AU - Alexandre, Anne

AU - Blard, Pierre Henri

AU - Tonetto, Alain

AU - Mazur, Jean Charles

AU - Bruneton, Hélène

PY - 2015/7/5

Y1 - 2015/7/5

N2 - During the last deglaciation, the Bolivian Altiplano (15-23°S, 66-70°W) was occupied by paleolake Tauca covering, at least, ~51,000 km2 at its maximum highstand between 16.5 and 15 ka. Twenty-five hundred years later, after a massive regression, a new transgressive phase, produced paleolake Coipasa, smaller than Tauca and restricted to the southern part of the basin. These paleolakes were overlooked at the west by the Sajama ice cap. The latter provides a continuous record of the oxygen isotopic composition of paleo-precipitation for the last 25 ka. Contemporaneously to the end of paleolake Tauca, around 14.3 ka, the Sajama ice cap recorded a significant increase in ice oxygen isotopic composition (δ18Oice). This paper examines to what extent the disappearance of Lake Tauca contributed to precipitation on the Sajama summit and this specific isotopic variation. The water δ18O values of paleolakes Tauca and Coipasa (δ18Olake) were quantitatively reconstructed from 18.5 to 11.7 ka based on diatom isotopic composition (δ18Odiatoms) and ostracod isotopic composition (δ18Ocarbonates) retrieved in lacustrine sediments. At a centennial time scale, a strong trend appears: abrupt decreases of δ18Olake during lake fillings are immediately followed by abrupt increases of δ18Olake during lake level stable phases. The highest variation occurred at ~15.8 ka with a δ18Olake decrease of about ~10‰, concomitant with the Lake Tauca highstand, followed ~400 years later by a 7‰ increase in δ18Olake. A simple hydro-isotopic modeling approach reproduces consistently this rapid "decrease-increase" feature. Moreover, it suggests that this unexpected re-increase in δ18Olake after filling phases can be partly explained by an equilibration of isotopic fluxes during the lake steady-state. Based on isotopic calculations during lake evaporation and a simple water stable isotopes balance between potential moisture sources at Sajama (advection versus lake evaporation), we show that total or partial evaporation (from 5 to 60%) of paleolake Tauca during its major regression phase at 14.3 ka could explain the pronounced isotopic excursion at Sajama ice cap. These results suggest that perturbations of the local hydrological cycle in lacustrine areas may substantially affect the paleoclimatic interpretation of the near-by isotopic signals (e.g. ice core or speleothems).

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