JCJC SIMI 5-6 - JCJC - SIMI 5-6 - Environnement, Terre et Espace

Spatio-chronological analysis of Altiplano paleoGlaciers during the lake Tauca episode (Heinrich 1): a case study for building a paleoprecipitation map in the Tropical Andes. – GALAC

GALAC

Spatio-chronological analysis of Altiplano paleoGlaciers during the lake Tauca episode (Heinrich 1): a case study for building a paleoprecipitation map in the Tropical Andes.

Glacier and lake : archives of the Altiplano paleoclimate

A major issue in paleoclimatology research is the development of new approaches to reconstruct the spatial variability of paleoprecipitations and paleotemperatures over the continents. The GALAC project will focus on a case study to improve the knowledge of the Andes paleoclimate. We will indeed use an innovative strategy to study the paleoclimate of the Altiplano, a high altitude region where the hydrosphere is likely to have recorded large climatic fluctuations. The project's main objective is to understand the atmospheric processes that led to the formation of the giant lake Tauca in the central Altiplano during the Heinrich 1 event (17-15 ka). To achieve this goal, and in particular to establish a map of the Altiplano paléoprecipitations during the lake Tauca highstands (synchronous with Heinrich event 1), we will implement a transdisciplinary strategy based on the reconstruction and cosmogenic 3He and 10Be dating of paleoglaciers, The presence of numerous Quaternary glacial relics in a remarkable state of preservation indicates that this region of the Andes is particularly well suited for the implementation of this method.

The first highly important task of the project is the discovery by our CRPG group of high quality calibrations sites in the Altiplano. These will allow defining regional reference production rates for cosmogenic 3He and 10Be. This is a key fundamental prerequisite before producing new glacial chronologies with precision and reliability. A special attention will be paid to define the equlibrium line of glaciers during the paleolake Tauca highstand (17-15 ka).
These new geochronological data will then be used to reconstruct the spatial variability of the regional cryosphere during the Lake Tauca. Because lakes and glaciers have very contrasted sensitivity to temperature and precipitation, it is possible to use their co-existence to reconstruct paleotemperatures and, most importantly, paleoprecipitations, with a very good spatial resolution. The interpretation of these data will be based on the joint modeling of the mass balance of glaciers and of the lake water balance.
Our preliminary results are particularly encouraging, we strongly hope that this project will generate new and important scientific findings for understanding the paleoclimate of the Tropical Andes.

September 2012 : establishement of an absolute 3He production rate in the Central Altiplano

Building a paleotemperature and paleoprecipitation map for the Altiplano during the Heinrich 1 event.

September 2012 : 1 paper submitted to EPSL.
2 others articles in preparation.

This project aims to better constrain the paleoclimaotlogical processes that led to the formation of the giant paleoLake Tauca, Central Altiplano during the Heinrich 1 event (17-15 ka BP). To reach this goal, we plan to build a paleoprecipitation map during Heinrich 1 by developing a multi-method program based on the reconstruction of the spatial variability of the paleo-equilibrium line of glaciers during this period. A significant milestone of the project will be to establish new geochronological data from cosmogenic 3He and 10Be dating of several paleoglaciated locations of the Altiplano. This task will permitt to establish the spatial pattern of the Altiplano paleoglaciers during the highstand of the paleolake Tauca (17-15 ka). Then, we will perform a joint modeling of the paleoglacier mass balances and of the lake hydrological budget during this period. Indeed, as lake and glaciers have contrasted sensitivities to precipitation and temperature, the synchronism of these two hydrosphere objects offers an unparalleled opportunity to solve the regional paleotemperatures and, most important, the spatial field of paleoprecipitation. This project aims to create a dynamic and fruitful collaborations by bringing together several young CNRS and IRD researchers having complementary skills : glacial geochronology, glaciology and climate modeling.

Project coordinator

Monsieur Pierre-Henri BLARD (CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE (CNRS) - DELEGATION REGIONALE CENTRE-EST) – blard@crpg.cnrs-nancy.fr

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

CRPG CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE (CNRS) - DELEGATION REGIONALE CENTRE-EST

Help of the ANR 175,583 euros
Beginning and duration of the scientific project: October 2011 - 48 Months

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