Although several glacier chronologies have been focused on the Southern part of the Tropical Andes, these efforts have not permitted yet to establish a common and integrated satisfactory scenario describing the global and regional forcing driving the glaciers fluctuations during the late-Pleistocene deglaciation. On the other hand, it is now well established that the endorheic basin of the Bolivian Altiplano has undergone several lake episodes during the same late Quaternary period. The largest ultimate highstand, the lake Tauca, was characterized by a ?100 m deep and 51,000 km² water body that persisted about 2 ka between 17 and 15 ka BP, synchronously with the Heinrich 1 event.
In this contribution we present new ³He and ¹⁰Be cosmogenic glacial chronologies from several localities in the vicinity of the paleolake Tauca. Along with the reinterpretation of existing Altiplano chronologies, our new data indicate that glacier persisted in a stationary position or possibly readvanced during the lake Tauca episode (17-15 ka). More interestingly, a spatial analysis of the glaciers positions indicates that synchronous Equilibrium-Line-Altitudes (ELA) are characterized by a significant regional variability. Importantly, they seem significantly controlled by their distance to the centre of the paleolake Tauca.
We use here a joint approach coupling a lake hydrological budget with the modeling of the glaciers ELA to propose a quantitative reconstruction of temperatures and precipitations at the scale of the Altiplano during this period. Such an integrated method is particularly relevant because glaciers and lakes have contrasted sensitivities to precipitation and temperature. Preliminary results allow establishing the regional pattern of paleoprecipitation over the Altiplano during the Heinrich 1 event (17-15 ka). Although further work remains necessary, this study is a first step toward the establishment of a high-resolution map of paleoprecipitation over the Tropical Andes.