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E407: Magmatism as a Key to Unlocking Phanerozoic Dynamic Topography (Lead Supervisor: Nicky White, Earth Sciences)

Supervisors: Nicky White (Earth Sciences) and John Maclennan (Earth Sciences

Importance of the area of research:

The diffculties of reconstructing dynamic topography through space and time can be surmounted by analyzing Phanerozoic magmatism. This inference is based upon a clear correlation between present-day magmatism and convectively-driven regional uplift. Furthermore, it can be shown that there is a quantitative relationship between the volume and composition of igneous rocks, and the size and shape of convective upwellings. Physical models, which have been used to advance our understanding of the links between composition, volume, asthenospheric temperature and lithospheric thickness, can be applied throughout the Phanerozoic record in order to analyze the spatial and temporal pattern of dynamic topography.

Project summary:

A good starting point will be the Cenozoic Era (e.g. western North America, South America, eastern Australia, western Arabia, Madagascar). Existing catalogues of basaltic igneous rocks will be analysed for major, trace, and rare Earth elements together with key isotopic ratios. These analyses will then be inverted as a function of melt fraction. This approach will enable us to constrain asthenospheric temperature beneath convective swells. Our approach will be integrated with other Cenozoic databases (e.g. drainage analyses, free-air gravity anomalies, lithospheric thickness estimates). In this way, analysis of present-day and Cenozoic magmatism will enable us to bench-mark geochemical variations with geodynamically significant parameters such as asthenospheric temperature.

What the student will do:

He/she will exploit publicly available inventories of geochemical analyses in the first instance. A series of fieldtrips will also be carried out to sample igneous rocks in regions of exploration interest.  Our general approach can then be applied to key periods of Phanerozoic magmatism (e.g. Cretaceous, Carboniferous, Cambrian). Otherwise unattainable details of the temporal variation of dynamic topography will be obtained and exploited.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Al-Hajri, Y., White, N., & Fishwick, S., 2009. Scales of transient convective support beneath Africa. Geology, 37, 883-886.

Poore, H., White, N., & Maclennan, J., 2011. Ocean circulation and mantle melting controlled by radial flow of hot pulses in the Iceland plume. Nature Geosciences, 4, DOI:10.1038/NGEO1161.

Parnell-Turner, R., White, N., Maclennan, J., Henstock, T., Murton, B., & Jones, S., 2013. Crustal manifestations of a hot transient pulse at 60 N beneath the Mid-Atlantic Ridge. Earth and Planetary Science Letters, 363, 109-120.

Follow this link to find out about applying for this project.

Other projects available from the Lead Supervisor can be viewed here.

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