Ian Meiklejohn

Marion Island volcanism and glaciation

Abstract Sub-Antarctic Marion Island was the site of extensive volcanism as well as glaciation during both the Quaternary and the Holocene. Initial reconstructions suggested a link between deglaciation and the initiation of faulting which, in turn, facilitated lava eruptions during the interglacials. However, our reassessment of the faulting, volcanic rock, and palaeoglacier distribution indicate that these original interpretations were erroneous. Features thought to be due to faulting are shown to be erosional scarps and this significantly changes interpretations of former glacier distribution. Further, the loss of the former ice cap has revealed new information on former glaciers and their flow directions, thereby allowing reconstruction of palaeoglaciers. Our new reconstruction fits with information from invertebrate genetic mapping that suggest some lava outcrops were nunataks and, therefore, refuges during the Last Glacial period. The new findings of glacial landforms in areas previously covered by snow suggest there was a significant ice advance during the Little Ice Age. Although Holocene volcanic rocks overlie and mask much of the glacial evidence, it has been possible to develop a proposed new reconstruction for glaciation, which is presented together with some of the implications.

Aqueous geochemistry as an indicator of chemical weathering on southeastern Alexander Island, Antarctica1

Abstract Chemical alteration of rock in the Antarctic is considered to be less dominant than physical weathering processes. The research presented in this discussion represents investigations to determine the extent of contemporary chemical weathering in an area that hitherto has not been investigated. A glacial outwash stream on southeastern Alexander Island was investigated to determine the extent of active chemical weathering. Data indicate that solution of minerals does take place during the Antarctic summer when water is present. Contrary to studies elsewhere in the Antarctic, there is little evidence of maritime or biological influences on the observed weathering regime. Although chemical weathering is active, its relative importance compared to that of physical weathering could not be determined.

Glaciation in Southern Africa and in the Sub-Antarctic

Abstract New studies from southern Africa provide evidence of spatially limited niche glaciation in the Drakensberg mountains. In the sub-Antarctic, evidence for ice extending further off-shore has been found for Heard Island and South Georgia, while a new glacial reconstruction for Marion Island has been presented.

Active layer monitoring in Antarctica: an overview of results from 2006 to 2015

Monitoring of active layer thawing depth and active layer thickness (ALT), using mechanical pronging and continuous temperature data logging, has been undertaken under the Circumpolar Active Layer ...

Temporal variability of ground thermal regimes on the northern buttress of the Vesleskarvet nunatak, western Dronning Maud Land, Antarctica

Abstract The ground temperature down to 60 cm depth in western Dronning Maud Land (WDML), has been recorded since 2009. The study area is situated in a blockfield that comprises a shallow active layer above permafrost. Using ground thermal regimes and regional climate data, the temporal (seasonal and annual) variability of the active layer was characterized. Active layer depth was calculated for each site for five consecutive summers from 2009/10–2013/14, showing interannual variability with no overall trends of decreasing or increasing active layer depth. Particular attention was paid to 2010 as it matched the average for the ground thermal regimes over the six year study period, as well as the interpolation period used by Meteonorm®. Analysis showed significant synchronous relationships of ground thermal regimes with air temperature and incoming radiation. Moreover, a correlation between pressure and measured ground temperature during the transitional season of the Southern Annual Oscillation in May and September was identified.