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

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.