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Ice thinning on nunataks during the glacial to interglacial transition in the Antarctic Peninsula region according to Cosmic-Ray Exposure dating: evidence and uncertainties
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Orientador(es)
Resumo(s)
The small ice caps distributed across the Antarctic Peninsula region have undergone large ice volume
changes since the Last Glacial Cycle, in line with most of the Antarctic continent. While the surface extent
of glacial shrinking is relatively well known, the timing of glacial oscillations and the magnitude of ice
thinning remain little investigated. Cosmic-Ray Exposure (CRE) dating applied on ice-free vertical sequences
can provide insights about the temporal framework of glacial oscillations. However, the potential
occurrence of nuclide inheritance may overestimate the real timing of the last glacial retreat. This
problem has been observed in many areas in Continental Antarctica, but similar studies have not yet
been conducted in environments of the Maritime Antarctica, such as the South Shetland Islands (SSI).
This research focuses on the Hurd Peninsula ice cap (HPIC, ca. 60 220 W, 62 40’ S), located in the SW of
Livingston Island, SSI. Past climate oscillations since the Last Glacial Cycle have determined the amount of
ice stored in the ice cap. Today, this polythermal ice cap is surrounded by several nunataks standing out
above the ice. Three of them have been selected to explore their deglaciation history and to test the
potential occurrence of nuclide inheritance in deglaciated bedrocks associated with polythermal glaciers.
We present a new dataset with 10 10Be exposure dates. Some of them were found to be anomalously old,
evidencing that nuclide inheritance is present in bedrocks associated with polythermal ice caps and
suggesting complex glacial exposure histories.We attribute this to limited erosion, given the gentle slope
of the nunatak margins and the cold-based character of the surrounding ice. The remaining samples
allowed to approach local surface-elevation changes of the HPIC. Our results suggest that ice thinning
started during the Last Glacial Maximum (LGM) at ~22 ka but intense glacial shrinking occurred from ~18
to ~13 ka, when the nunataks became exposed, being particularly intense at the end of this period (~14
e13 ka) coinciding with the time of the meltwater pulse 1a (MWP-1a) and the end of the Antarctic Cold
Reversal (ACR).
Descrição
Palavras-chave
Antarctica South Shetland Islands Hurd Peninsula ice cap Nunataks Ice thinning Nuclide inheritance
Contexto Educativo
Citação
Fernández-Fernández, J. M., Oliva, M., Palacios, D. Garcia-Oteyza, J., . . . & ASTER Team (2021). Ice thinning on nunataks during the glacial to interglacial transition in the Antarctic Peninsula region according to Cosmic-Ray Exposure dating: evidence and uncertainties. Quaternary Science Reviews, 264, 107029. https://doi.org/10.1016/j.quascirev.2021.107029
Editora
Elsevier