Supervisors: Joanne Johnson (British Antarctic Survey), Oliver Shorttle , and John Smellie (University of Leicester)
Importance of the area of research:
Loading of the mantle by ice sheets on the surface of the Earth modulates the extent and style of volcanism over geological timescales. Unloading of the mantle during deglaciations in Iceland has resulted in increases in the degree of melting and consequent surges in volcanism at the surface, accompanied by changes in magma geochemistry. Links between volcanism and climate are fundamental to the outgassing of our planet over geological timescales yet the mechanisms and feedbacks involved are poorly understood. Present-day retreat of ice sheets may have implications for future volcanism and emissions to the atmosphere.
Understanding the feedbacks between glaciation, volcanism, and climate is critical not only for understanding the history of Earth’s climate, but also for providing a long-term context for recent emissions from human activity. A recent study showed that glacial unloading roughly tripled global volcanic activity during the last deglaciation, but only one Antarctic volcano was included in the study. This interdisciplinary project will focus on understanding how glaciation has influenced the geochemical evolution of lavas from a large stratovolcano that has erupted frequently (>50 times) beneath the Antarctic ice sheet over multiple glacial cycles (over 6 Ma).
What the student will do:
The project presents an exciting opportunity for the student to undertake state-of-the-art geochemical analyses on a unique suite of lavas and hyaloclastites already collected from Mount Haddington, James Ross Island, on the northern Antarctic Peninsula. These lavas were erupted beneath the Antarctic Peninsula Ice Sheet over the past 6 million years, a period of time during which ice cover was variably present. The thicknesses of ice have been estimated from the morphologies of the flows (Smellie et al., 2008). The student will have the opportunity to pursue novel geochemical approaches such as melt inclusion and isotopic studies, using a range of analytical techniques. Models will be developed to understanding the impact of multiple glaciations on the evolution of mantle melting and associated outgassing.
Hartley, M., Maclennan, J., Edmonds, M., Thordarson T. 2014. Reconstructing the deep CO2 degassing behaviour of large basaltic fissure eruptions. Earth and Planetary Science Letters, vol. 393, pp.120-131
Johnson, J.S., Smellie, J. L., Nelson, A. E., Stuart, F. M. 2009. History of the Antarctic Peninsula ice sheet since the early Pliocene - evidence from cosmogenic dating of Pliocene lavas on James Ross Island, Antarctica. Global and Planetary Change, vol. 69, pp.205-213
Smellie, J. L., Johnson, J. S., McIntosh, W. C., Esser, R., Gudmundsson, M. T., Hambrey, M. J., van Wyk de Vries, B. 2008. Six million years of glacial history recorded in volcanic lithofacies of the James Ross Island Volcanic Group, Antarctic Peninsula. Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 260, pp.122-148
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