The expression of Heinrich Event 2 in Alpine speleothems

Terrestrial archives of the last glacial maximum (LGM) are remarkably rare across Switzerland which was largely covered
with ice (Bini et al., 2009). Characterizing the LGM paleoclimate is nonetheless critical to reconstruct the glacier dynamics
and thus understand processes which drove the regional landscape evolution. The Sieben Hengste cave system (7H) has
revealed continuous deposition of speleothems across the LGM, suggesting that glacier build-up took advantage of
enhanced southerly moisture advection between 26.5 and 23.5 ka (Luetscher et al., 2015). Surprisingly, the 7H record
reveals only a buffered oxygen isotope signal at the time of Heinrich event 2. Here, we compare this original record with
two new speleothems recovered nearby the initial sampling site. These stalagmites are characterized by a markedly distinct
petrography indicating contrasted hydrological regimes. We discuss the paleoclimate interpretation of these groups of
speleothems and suggest that the northern Alps may have been subject to enhanced summer aridity during the time period
covering Heinrich stadial 2. These results are compared with regional sedimentary records and discussed with respect to
the Alpine glacier dynamics during the LGM.