The upper Cenozoic tephra record in the south polar region: a review

Abstract

Tephrochronology studies in the south polar region are reviewed and evaluated. There have been numerous investigations of tephra layers in ice cores, reflecting the continuing importance of ice cores as a principal source of palaeoenvironmental information. By contrast, tephra in marine sediment cores have been largely neglected. Chemical analyses of glass shards are not uniformly available across the region. In particular, they are currently unavailable for the northern Antarctic Peninsula. Few tephras have been dated directly, although potassic glass and minerals are commonly present and should be readily amenable to isotopic dating. Chemical ‘fingerprinting’ seems to have a high potential for successfully correlating layers and identifying source areas, but only a few studies have considered trace elements as well as major oxides. The effects of within-ash compositional variations and analytical imprecision limit the general utility of ‘fingerprinting’. The tephra record is locally much more complete than is preserved in the source volcanoes themselves. However, the effects of frequent eruptions on local depocentres may swamp other environmentally significant indicators and make the environmental record harder to interpret than in tephra-free successions. Linked studies of tephra and volcanically-derived aerosols in ice in the south polar region could be of critical importance for quantitative calculations of the volcanic contribution to atmospheric fluxes and attempts to assess the possible effects of volcanism on global climate.