Abstract Details
| ID: | 2617 |
| Title: | Mid to Late Holocene Glacier Variations in Central Caucasus, Russia |
| Content: | Here we present a combined 10Be, 14C, tree-ring and lichens-based glacial chronology for the Holocene in Central Caucasus. At Bezengi glacier five glacial advances from buried detritus and peat layers were dated by radiocarbon 1- before 8600±350 yrs BP (tln-416), 2 -between 8600±350 14C yrs BP and 6480±500 14C yrs BP (Mo-822), 3 - between 6480±500 14C yrs BP and 4250±80 14C yrs BP (TA-866) yrs BP, 4 - after 3350±7014C yrs BP (TA-865), and 5 - before AD 1220-1440 (TA-867) (Serebrianny et al., 1984). In summer 2009 we collected three samples from the top of large boulders at the moraine located 6,2 km away from the Bezengi glacier. They all yielded close 10Be exposure ages around 5.6-6 ka (5853±291, 6032±244, 5632±294) and roughly correspond to the stage 3. These new 10Be dates revealed that the advance at 5.6-6.0 ka in Caucasus was very prominent and larger than the Late Holocene glacial extents. Such mid Holocene glacial advance was reported in the Alps but its scale was minor. A buried soil found one km away from the Ullukam glacier (3580±80 14C yrs BP (IGRAS-3790) revealed a retreat phase due to warmer conditions that were confirmed by archeological data. At 3.8-3.4 ka the Bezengi glacier was readvancing synchronously with the beginning of the Neoglacial in the Alps (Ivy-Ochs, 2009). Tree-ring, lichenometry and historical data enabled us to date glacial advances in the last millennium: earlier AD 1590s and AD 1550s, AD1839-1840, three times between AD1870s and AD1890s. The historically constrained glacier variations in Caucasus and those in the Alps are believed to be largely synchronous (Grove, 1988). However our results show that so far the dates for the advances predating the mid 19th century in Caucasus vary from those in the Alps. New 10Be samples (analysis in progress) collected on late Holocene moraine stages should improve our knowledge in this region soon. |
| Session: | 15 Holocene Glacier Variability from the Tropics to the Poles |
| Authors: |
Olga Solomina Vincent Jomelli Régis Braucher Didier L. Bourlès Irina Bushueva |
| Presenter: | Vincent Jomelli |
| Type: | oral |
