A new cosmogenic nuclide (10Be) record for reconstructing Holocene glacier change in the Eastern European Alps (Austria)
Abstract
Holocene glacier and climate change across the European Alps is important for discerning local variability and for evaluating anthropogenic impact relative to natural variability. Glaciers respond rapidly to climate change and deposit sediments along their ice margins during cold periods. Mapping and dating of ice margin deposits such as moraines using Surface Exposure Dating (SED) allows assigning spatial and timely constraints to past glacier culminations, which deepens our knowledge on long- and short term climate variability, and helps to identify local, regional and over-regional patterns of climate change in the European Alps. While in the Western and Central Alps, 10Be SED has been used in recent years to generate Holocene moraine records, comparable studies in the Eastern Alps are scarce.
Here, we present a comprehensive Holocene moraine chronology in Austria, in the Eastern Alps. We mapped and dated glacial deposits marking Holocene ice margins using SED. Our objectives are to test (1) how the timing and magnitude of Holocene glacier advances in the Eastern Alps compares to patterns of glacier advances reported in the Central and Western Alps, (2) if SED is apt to resolve individual glacier advances during the Little Ice Age (LIA) c. 1300 to 1850 CE, and (3) if our LIA glacier chronology is in agreement with historical maps. (1) Bedrock ages suggest deglaciation in our study area at the beginning of the Holocene followed by a phase of glacier stabilization around 10 ka indicated by moraine formation. These results are consistent with glacier reconstructions from the Western and Central Alps. (2) Multiple glacier advances during the LIA could be dated in stratigraphic order, i.e. younger boulder ages being located inside older LIA ice margins. A clustering of ages c. 1750 CE points towards a sustained period of high glacial activity at that time. (3) Youngest boulder ages are validated by ice margin positions illustrated in historical maps making a case for the 10Be record's overall robustness. In our study area, glaciers were in similar positions during the early Holocene and during the LIA, a finding, which in a next step will be tested on a regional scale.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC11D1139B
- Keywords:
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- 1105 Quaternary geochronology;
- GEOCHRONOLOGY