A new Eemian record of Antarctic tephra layers retrieved from the Talos Dome ice core (Northern Victoria Land)

Biancamaria Narcisi (1) , Jean Robert Petit (2) , Antonio Langone (3) , Barbara Stenni (4)

1 ENEA - Ente per le Nuove Technologie, l'Energia e l'Ambiente
2 LGGE - Laboratoire de glaciologie et géophysique de l'environnement
3 IGG-CNR
4 Dipartimento di Scienze Geologiche [Trieste]

Polar ice sheets are remarkable repositories of tephra layers. The Talos Dome ice core (72°49′S, 159°11′E), drilled at the edge of the East Antarctic Plateau, close to Late Quaternary volcanoes, offers considerable potential to extend the current tephra time-stratigraphic framework. A tephrochronological study was undertaken of the ice core sections related to the Last Interglacial and the transition to the subsequent glacial period. Thirteen macroscopically visible layers, interpreted to be related to primary deposition of fallout tephra, have been analysed for quantitative grain size and glass shard geochemistry. The layers, precisely framed within the climate (δ18O) record for the core, span in age from 111.6 ± 1.9 to 123.3 ± 2.2 ka. Coarse particle size suggests origin from regional sources. Indeed, the vast majority of the samples display an alkaline affinity and trachytic composition that are both typical geochemical features of rifting Antarctic volcanism. Using subtle differences in the geochemical signatures and the comparison with data from previous studies, a few layers are attributed to known coeval Mt. Melbourne eruptions. Another sample subset is consistent with derivation from The Pleiades and Mt. Rittmann volcanoes. One peculiar trachytic glass population appears to be related to activity of the more distant Marie Byrd Land volcanoes. The newly detected tephras provide stratigraphic markers that could facilitate future synchronisation and dating of palaeoclimatic records. The Talos Dome tephra inventory also contributes significantly to the reconstruction of the Northern Victoria Land explosive volcanism, for which chronostratigraphic data for the Last Interglacial temporal segment are poor.

Mots clés: Tephra layers; Antarctic ice cores; Last Interglacial; Glass shard microanalysis; Tephrostratigraphy; Northern Victoria Land volcanism

Domaines: Sciences de l'environnement

Biancamaria Narcisi, Jean Robert Petit, Antonio Langone, Barbara Stenni. A new Eemian record of Antarctic tephra layers retrieved from the Talos Dome ice core (Northern Victoria Land). Global and Planetary Change, 2016, 137, pp.69 - 78. ⟨10.1016/j.gloplacha.2015.12.016⟩. ⟨insu-01351730⟩