Dataset Information

Summer paleohydrology during the Late Glacial and Early Holocene based on δ²H and δ¹⁸O from Bichlersee, Bavaria.

ABSTRACT: Isotope-based records provide valuable information on past climate changes. However, it is not always trivial to disentangle past changes in the isotopic composition of precipitation from possible changes in evaporative enrichment, and seasonality may need to be considered. Here, we analyzed δ²H on n-alkanes and δ¹⁸O on hemicellulose sugars in sediments from Bichlersee, Bavaria, covering the Late Glacial and Early Holocene. Our δ²H_n-C31 record documents past changes in the isotopic composition of summer precipitation and roughly shows the isotope pattern known from Greenland. Both records show lower values during the Younger Dryas, but at Bichlersee the signal is less pronounced, corroborating earlier suggestions that the Younger Dryas was mainly a winter phenomenon and less extreme during summer. δ¹⁸O_fucose records the isotopic composition of the lake water during summer and is sensitive to evaporative enrichment. Coupling δ²H_n-C31 and δ¹⁸O_fucose allows calculating lake water deuterium-excess and thus disentangling changes in the isotopic composition of precipitation and evaporative enrichment. Our deuterium-excess record reveals that the warm Bølling-Allerød and Early Holocene were characterized by more evaporative enrichment compared to the colder Younger Dryas. Site-specific hydrological conditions, seasonality, and coupling δ²H and δ¹⁸O are thus important when interpreting isotope records.

SUBMITTER: Prochnow M

PROVIDER: S-EPMC10613243 | biostudies-literature | 2023 Oct

REPOSITORIES: biostudies-literature

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Publications

Summer paleohydrology during the Late Glacial and Early Holocene based on δ2H and δ18O from Bichlersee, Bavaria.

Prochnow Maximilian M Strobel Paul P Bliedtner Marcel M Struck Julian J Bittner Lucas L Szidat Sönke S Salazar Gary G Schneider Heike H Acharya Sudip S Zech Michael M Zech Roland R

Scientific reports 20231028 1

Isotope-based records provide valuable information on past climate changes. However, it is not always trivial to disentangle past changes in the isotopic composition of precipitation from possible changes in evaporative enrichment, and seasonality may need to be considered. Here, we analyzed δ2H on n-alkanes and δ18O on hemicellulose sugars in sediments from Bichlersee, Bavaria, covering the Late Glacial and Early Holocene. Our δ2Hn-C31 record document ...[more]

PMID: 37898674

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Project description:Climate is currently warming due to anthropogenic impact on the Earth's atmosphere. To better understand the processes and feedbacks within the climate system that underlie this accelerating warming trend, it is useful to examine past periods of abrupt climate change that were driven by natural forcings. Glaciers provide an excellent natural laboratory for reconstructing the climate of the past as they respond sensitively to climate oscillations. Therefore, we study glacier systems and their behavior during the transition from colder to warmer climate phases, focusing on the period between 15 and 10 ka. Using a combination of geomorphological mapping and beryllium-10 surface exposure dating, we reconstruct ice extents in two glaciated valleys of the Silvretta Massif in the Austrian Alps. The mountain glacier record shows that general deglaciation after the Last Glacial Maximum (LGM) was repeatedly interrupted by glacier stabilization or readvance, perhaps during the Oldest Dryas to Bølling transition (landform age: 14.4 ± 1.0 ka) and certainly during the Younger Dryas (YD; 12.9-11.7 ka) and the Early Holocene (EH; 12-10 ka). The oldest landform age indicates a lateral ice margin that postdates the 'Gschnitz' stadial (ca. 17-16 ka) and predates the YD. It shows that local inner-alpine glaciers were more extensive until the onset of the Bølling warm phase (ca. 14.6 ka), or possibly even into the Bølling than during the subsequent YD. The second age group, ca. 80 m below the (pre-)Bølling ice margin, indicates glacier extents during the YD cold phase and captures the spatial and temporal fine structure of glacier retreat during this period. The ice surface lowered approximately 50-60 m through the YD, which is indicative of milder climate conditions at the end of the YD compared to its beginning. Finally, the third age group falls into a period of more substantial warming, the YD-EH transition, and shows discontinuous glacier retreat during the glacial to interglacial transition. The new geochronologies synthesized with pre-existing moraine records from the Silvretta Massif evidence multiple cold phases that punctuated the general post-LGM warming trend and illustrate the sensitive response of Silvretta glaciers to abrupt climate oscillations in the past.

Dataset Information

Summer paleohydrology during the Late Glacial and Early Holocene based on δ²H and δ¹⁸O from Bichlersee, Bavaria.

Publications

Summer paleohydrology during the Late Glacial and Early Holocene based on δ<sup>2</sup>H and δ<sup>18</sup>O from Bichlersee, Bavaria.

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