Climate variability on the Adriatic seaboard during the last glacial inception and MIS 5c from Frasassi Cave stalagmite record
Résumé
A stalagmite (FR16) from Frasassi Cave, located near the Adriatic coast of the Italian peninsula, offers a 16 kyr petrographic and stable isotope record spanning from 112.8 ± 1.5 ka to 96.6 ± 1.0 ka, corresponding to the interval from marine isotope stage (MIS) 5c to MIS 5d. The physical characteristics of FR16 calcite, allowed for a thorough understanding of the processes controlling isotopic changes, because fabrics as well are controlled by the environmental parameters within the cave that reflect external climate forcing. The FR16 δ13C profile matches fabric changes where columnar fabric usually corresponds to more negative values and micrite/microsparite layers to less negative δ13C values, and with the North Greenland Ice-core Project (NGRIP) δ18O record with more negative δ13C values during interstadials GI24 and GI23. This suggests a hydrological sensitivity for the two proxies, and their variability can be linked to recharge changes. On the other hand, the response to Greenland events appears subdued in the δ18O record and the trend mimics instead the Northern Hemisphere (NH) summer insolation with more negative δ18O values corresponding to the maximum insolation centred at ca. 105 ka. This behaviour can be explained by the higher sensitivity of δ18O to rainfall seasonality, moisture source and trajectories, whose combined effect attenuated the stadials/intersadials signal in the stalagmite