Geomorphological evidence and Be-10 exposure ages for the Last Glacial Maximum and deglaciation of the Velka and Mala Studena dolina valleys in the High Tatra Mountains, central Europe
Abstrakt
10Be exposure age chronology of the last glaciation was established in a key area at the southern slopes of the High Tatra Mts., Western Carpathians. In-situ produced 10Be in moraine boulders, glacially transformed bedrock surfaces and rockfall accumulations constrains the timing of the Last Glacial Maximum glacier expansion and provides chronological evidence for the post-LGM decay of one of the largest paleoglaciers in the range.
The uncertainty-weighted mean age of 22.0 +- 0.8 ka obtained for the terminal moraine in the forefield of the Velká Studená dolina Valley indicates that the oldest moraine was deposited close to the global LGM. This finding confirms that well-preserved moraines in the range were formed during the last glacial cycle and that glaciation on the southern flank of the range was more extensive than earlier in the last glacial cycle.
The maximum glacier extent correlates with late Würmian/Weichselian glacier phases in the Alps, the Bavarian/Bohemian Forest and the Krkonoše Mts., but probably postdates the period of maximum glaciation in the Southern Carpathians. Re-advance moraines at the mouth of the Velká Studená dolina Valley and in the middle part of the Malá Studená dolina Valley were deposited no later than around 20.5 ka and 15.5 ka, respectively.
The timing of these advances is broadly synchronous within the High Tatra Mts. as well as with glacier advances in the Alps, Bavarian/Bohemian Forest and Krkonoše Mts. 10Be exposure ages obtained from glacially transformed bedrock surfaces range between 20.5 +- 1.7 ka and 10.7 +- 0.3 ka constraining the onset and the final phase of the deglaciation. Surface exposure dating of four rockfall accumulations produced uncertainty-weighted mean ages of 20.2 +- 1.2 ka, 17.0 +- 0.7 ka, 16.5 +- 0.4 ka and 15.6 +- 0.7 ka.
These ages indicate that activation of rock-slope failures occurred under paraglacial conditions within a few centuries up to 1400 years after the formation of re-advance moraines.