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Reconstructing the eruptive activity of Mount Melbourne in northern Victoria Land (Antarctica), characterization of englacial tephra deposits from the southwest flank

Giulia Fisauli 1, Alessio Di Roberto 2, Giuseppe Re 2, Maurizio Petrelli 1, Paola Del Carlo 2

  • Affiliations: 1 Department of Physics and Geology, University of Perugia, Perugia, Italy 2 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, Pisa, Italy 

  • Presentation type: Talk

  • Presentation time: Tuesday 09:15 - 09:30, Room S150

  • Programme No: 3.13.4

  • Theme 3 > Session 13

Abstract

We present a comprehensive characterization of tephra deposits discovered within an ice sequence on the southwest flank of Mount Melbourne, located in northern Victoria Land, Antarctica. This study focuses on the detailed analysis of three distinct fallout tephra layers DPT 1, DPT 2 and DPT 3, including textures, components, major and trace elements single glass composition. DPT 1 represents the lowermost layer and is composed of pumiceous lapilli and ash, it is moderately to highly vesicular with a predominantly aphyric groundmass and rare euhedral to subhedral crystals. DPT 2 is the intermediate layer and consists of dense, poorly vesicular glass shards embedded in a glass matrix ranging from microlite-poor to nearly crystallized. DPT 3 is the uppermost layer, it looks dense to poorly vesicular scoriaceous fragments, rich in microlites and nearly fully crystallized. These deposits are predominantly trachytic, with occasional transitions to trachyandesitic compositions. Major and trace element compositions strongly suggest that they originate from the explosive activity of Mount Melbourne. Notably, no direct correlation was found with previously studied tephra attributed to this volcano, indicating that they represent deposits from three yet undiscovered eruptions, one of which is particularly significant in terms of energy. Therefore, the integration of DPT 1-2-3 within the regional tephra framework from previously studied marine sediments and ice core tephra enhances our understanding of the explosive activity of Mount Melbourne. These insights are also crucial for evaluating volcanic hazards, particularly given the proximity of Mount Melbourne to polar air traffic routes and scientific research stations.