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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities
 

Lead Supervisor: Sergei Lebedev, Earth Sciences

Co-Supervisor: Nick Rawlinson, Earth Sciences

Brief summary: 
New seismic data from the North Atlantic seafloor will be used to study the structure and dynamics of the region, the Iceland Plume, and the origin of the North Atlantic Igneous Province.
Importance of the area of research concerned: 
Prior to the onset of seafloor spreading in the NE Atlantic Ocean ~60 million years ago, large basalt eruptions, such as at the Giant’s Causeway in N Ireland or Fingal’s Cave in Scotland, were scattered across the region. The vast North Atlantic Igneous Province (NAIP) now stretches from western Greenland and Baffin Island in the west to Ireland and Great Britain in the east. Today, volcanic activity continues in Iceland, attributed to the Iceland plume, an upwelling of hot mantle rock from the core-mantle boundary. The formation of the NAIP has also been attributed to this plume, but its eruptions were not focused in the same area but, rather, scattered across thousands of km, which presents a puzzle. A possible explanation for this is channelling of hot plume material through thin-lithosphere corridors, but mapping such corridors—or flow in the mantle—has been difficult due to the data gaps in the Atlantic Ocean. The recently completed experiment SEA-SEIS has filled a large part of the gap. Seismic imaging using SEA-SEIS data, along with data from both sides of the Atlantic, can answer long-standing questions on the origin of the volcanism and the region’s dynamics.
Project summary : 
The SEA-SEIS deployment (www.sea-seis.ie) provided, for the first time, broadband seismic data from across a large part of the northeast Atlantic Ocean. The goal of this project is to apply a suite of complementary seismic imaging methods to the entire SEA-SEIS dataset in order to study the structure and dynamics of the region. Surface wave data, shear-wave splitting data and teleseismic receiver functions will be used to determine the structure of the lithosphere, the current flow in the asthenosphere, and the thickness of the mantle transition zone, indicative of its temperature. The results will be interpreted together with other geophysical and geological data and bring important new evidence on the structure of the enigmatic Iceland Plume and its effects on the dynamics and evolution of the entire North Atlantic region.
What will the student do?: 
The student will analyse and interpret unique seismic data. They will learn and apply a suite of state of the art seismic imaging methods. Surface-wave analysis will yield information on the structure of the lithosphere and underlying mantle. Shear-wave splitting analysis will provide complementary information on the anisotropy and, by inference, flow of the rock in the asthenosphere. Teleseismic receiver functions will provide further information on the structure of the crust and lithosphere. Importantly, they will also determine the thickness of the mantle transition zone (410-660 km depths), indicative of its temperature. This will yield essential information on the up and down flow—hot upwellings and cold downwellings—from and to the lower mantle, important for understanding the Iceland Plume and the North Atlantic mantle dynamics. The interpretation of the results will be multi-disciplinary, with a global geodynamic approach to the problem and with multiple lines of geological and geophysical evidence incorporated. Seismic imaging and interpretation will be in collaboration with leading Cambridge and international experts.
References - references should provide further reading about the project: 
Lebedev, S., R. Bonadio, M. Tsekhmistrenko, J.I. de Laat, C.J. Bean, 2021. Seafloor seismometers look for clues to North Atlantic volcanism, EOS, 102, https://doi.org/10.1029/2021EO159380.
Bonadio, R., S. Lebedev, T. Meier, P. Arroucau, A.J. Schaeffer, A. Licciardi, M.R. Agius, C. Horan, L. Collins, B.M. O'Reilly, P. Readman & the Ireland Array Working Group, 2021. Optimal resolution tomography with error tracking and the structure of the crust and upper mantle beneath Ireland and Britain. Geophys. J. Int., 226, 2158-2188, https://doi.org/10.1093/gji/ggab169.
Steinberger, B., E. Bredow, S. Lebedev, A. Schaeffer, T. H. Torsvik, 2019. Widespread volcanism in the Greenland-North Atlantic region explained by the Iceland plume. Nature Geoscience, 12, 61–68, doi:10.1038/s41561-018-0251-0.
Applying
You can find out about applying for this project on the Department of Earth Sciences page.
Sergei Lebedev
Prof Nicholas Rawlinson
Department of Earth Sciences Graduate Administrator