Abstract
In the northern Antarctic Peninsula area, at least 12 Late Pleistocene-Holocene volcanic centers could be potential sources of tephra layers in the region. We present unique geochemical fingerprints for ten of these volcanoes using major, trace, rare earth element, and isotope data from 95 samples of tephra and other eruption products. The volcanoes have predominantly basaltic and basaltic andesitic compositions. The Nb/Y ratio proves useful to distinguish between volcanic centers located on the eastern (Larsen Rift) and those situated on the western side (Bransfield Rift) of the Antarctic Peninsula. In addition, the Sr/Nb ratio (for samples with SiO2 <63 wt%), along with Sr/Y, Ba/La, Zr/Hf and Th/Nb are suitable to unequivocally characterize material erupted from every studied volcanic center. Microprobe analyses on volcanic glass show that the samples are generally very poor in K2O, and that glass from Bransfield Rift volcanoes is enriched in SiO2, while that of Larsen Rift volcanoes tends towards elevated alkali contents. We propose an algorithm for the identification of the source volcano of a given tephra layer using the new geochemical fingerprints. This will contribute to the development of a regional tephrochronological framework needed for future correlations of tephra in climate archives (e.g., marine, lacustrine and ice cores).
Highlights
In the northern part of the Antarctic Peninsula there are at least a dozen volcanic centers that are potentially capable of dispersing volcanic ash over large areas (Fig. 1)
The Nb/Y ratio proves useful to distinguish between volcanic centers located on the eastern (Larsen Rift) and those situated on the western side (Bransfield Rift) of the Antarctic Peninsula
Subducted sediments as one of the possible contributors to magma formation beneath Bransfield Rift might be reflected by enrichment of the light rare earth elements (LREE) relative to heavy rare earth elements (HREE), generally high Th abundances expressed as high Th/Ce and low U/Th, low Ta/Nd and Nb/Nd, high Pb isotope ratios, low εNd values and negative Ce anomalies (Hawkesworth et al, 1997; Turner and Hawkesworth, 1997; Turner et al, 2000; Elliott, 2003)
Summary
In the northern part of the Antarctic Peninsula there are at least a dozen volcanic centers that are (or have been in the past) potentially capable of dispersing volcanic ash over large areas (Fig. 1). Over the past few decades, a range of studies on the volcanic products generated by these volcanoes (Baker et al, 1975; Palais and Kyle, 1988; Björck et al, 1991a, 1993; Hodgson et al, 1998; Smellie, 1999a, b, 2001; Fretzdorff and Smellie, 2002; Fretzdorff et al, 2004; Gibson and Zale, 2006; Kraus and Kurbatov, 2010) has contributed to the development of a tephrochronological framework that can be used to identify potential source volcanoes within the Antarctic continent. This article presents a comprehensive geochemical dataset on compositions of tephra and other volcanic products from Late Pleistocene-Holocene Antarctic Peninsula volcanoes, including trace and rare earth element signatures and Sr-Nd-Pb isotopy. We discuss differences for every sampled volcanic center and provide geochemical signatures that can be used for future discrimination of volcanic products in paleoclimate archives
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