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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities
 

Lead Supervisor: Marie Edmonds, Earth Sciences

Co-Supervisors: John Maclennan, Earth Sciences & Margaret Hartley, University of Manchester

Importance of the area of research concerned: 
Diffuse degassing has been shown to make up a large fraction of the global volcanic carbon budget. Diffuse degassing takes place through faults and fractures, derived from deep-stored magma bodies in the crust, which may or may not erupt. Microseismicity beneath the neovolcanic zone in Iceland has been linked to the degassing of CO2 from sill-stored magmas fracturing the overlying crust. Diffuse degassing is well-characterised in many areas of the world and these studies have shown that this mode of degassing dominates in the East African rift, and in arc settings. Very little is understood about the deep carbon budget of magmas beneath Iceland. Petrological studies have reconstructed the carbon budget of magmas, and have predicted substantial carbon degassing prior to eruption. Does this carbon dioxide migrate to the surface ahead of the magma? How much CO2 is sequestered by groundwater? Would a monitoring network of CO2 sensors provide early warning signals of impending eruptions?
Project summary : 
This project will seek to quantify the diffuse degassing budget of carbon from the Askja region of Iceland. Askja is a large volcanic system which stretches 200 km from beneath the Vatnajökull glacier to the northern coastline. The project will focus on the area around the Askja caldera, and fissures that have been recently active south of the caldera. Grid-based measurements of CO2 degassing through soils and fractures will be carried out using portable IR spectrometers, and using CO2 sensors mounted on unmanned aerial vehicles to obtain estimates of CO2 flux integrated across the area. These CO2 fluxes will be compared to the reconstructed carbon budgets of erupted magmas in this part of the Askja system, and used to infer the likely volume and depth of magmas in the crust beneath. The potential utility of CO2 monitoring for forecasting eruptions will be assessed.
What will the student do?: 
The student will undertake field measurements of diffuse degassing using NDIR spectrometers in the Askja region of Iceland; and will use these measurements, acquired over two field seasons, to estimate the outgassing flux of CO2 for this part of the rift zone. Gases, geothermal waters and subsurface carbonate deposits will be sampled and their carbon isotope composition analysed using mass spectrometry. The data will be used to infer the likely depth and volume of any currently stored magma, as well as predict the likely pre-eruptive signal that might be caused by magmas moving towards the surface.
References: 
Hartley ME, Maclennan J, Edmonds M, Thordarson T. Reconstructing the deep CO2 degassing behaviour of large basaltic fissure eruptions. Earth and Planetary Science Letters. 2014 May 1;393:120-31.
White RS, Edmonds M, Maclennan J, Greenfield T, Agustsdottir T. Melt movement through the Icelandic crust. Philosophical Transactions of the Royal Society A. 2019 Jan 7;377(2139):20180010.
Illyinskaya E, Mobbs S, Burton R, Burton M, Pardini F, Pfeffer MA, Purvis R, Lee J, Bauguitte S, Brooks B, Colfescu I. Globally significant CO2 emissions from Katla, a subglacial volcano in Iceland. Geophysical Research Letters. 2018 Oct 16;45(19):10-332.
Applying
You can find out about applying for this project on the Department of Earth Sciences page.