Expanding the tephrostratigraphical framework for the South Shetland Islands, Antarctica, by combining compositional and textural tephra characterisation

Liu, E. J. and Oliva, M. and Antoniades, D. and Giralt, S. and Granados, I. and Pla-Rabes, S. and Toro, M. and Geyer, A. (2016) Expanding the tephrostratigraphical framework for the South Shetland Islands, Antarctica, by combining compositional and textural tephra characterisation. Sedimentary Geology, 340. pp. 49-61. ISSN 00370738 DOI https://doi.org/10.1016/j.sedgeo.2015.08.002

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Official URL: http://doi.org/10.1016/j.sedgeo.2015.08.002

Abstract

Tephra layers preserved in lake sedimentary sequences provide valuable isochrons with which to synchronise palaeoclimatic records. However, in regions where tephra inputs are dominated by a single volcanic source, overlapping chemical compositions can preclude unambiguous correlation of tephra layers. In this study, we characterise multiple visible (macrotephra) layers within sedimentary sequences from three lakes in Byers Peninsula, Antarctica. By combining compositional analyses with additional constraints from textural componentry, we identify three distinct tephra isochrons—T1, T2, and T3—each with distinct textural properties. The relative proportion of glassy compared to crystal-rich grains varies from ~ 50% (T3) to ~ 3% (T1) of the total sample. Although the proportion of dense to vesicular grains differs only slightly between all sampled tephra layers, the dominant vesicle shape varies from spherical (T3) to irregular and polylobate (T1/T2). These textural differences can be related to variations in the eruptive processes occurring at the Deception Island source volcano. This study highlights the efficacy of a correlative approach based on both chemical and physical tephra properties for deconvolving the tephra stratigraphy in regions where chemical compositions are non-unique.

Item Type: Article
Uncontrolled Keywords: NILAREP; IA70
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Journal or Publication Title: Sedimentary Geology
Volume: 340
Page Range: pp. 49-61
Identification Number: https://doi.org/10.1016/j.sedgeo.2015.08.002
Depositing User: Sarah Humbert
Date Deposited: 23 May 2018 09:21
Last Modified: 23 May 2018 09:21
URI: http://eprints.esc.cam.ac.uk/id/eprint/4285

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