About the Project
Some of the World’s most significant gold deposits are rich in tellurium, and are hosted in alkalic or adakite-like igneous host rocks. Despite the economic importance of Au-Te ore deposits, the underlying processes which link them to particular types of magmas are poorly understood. This project will seek to address this important knowledge gap Fieldwork will be coupled with state-of-the-art analytical techniques and interpretation.
The research will focus on the magmatic history of the Metaliferi Mountains (part of the Apuseni Mountains) in Romania. This area hosts world–class examples of Au-Ag-Te epithermal and porphyry mineralisation (Cioacă et al. 2014). Current research indicates that the magmatism is not directly related to subduction, despite being predominantly calc-alkaline in nature and bearing the geochemical hallmarks of subduction. Instead, various groups have suggested that the magmas are produced by partially melting metasomatised mantle during crustal extension (Harris et al. 2013). This project will test an alternative hypothesis: that lower crustal cumulates are reworked to produce alkaline melts. The two steps – fractionation then remelting – give the magmas their distinctive Au-Te “flavour”.
Metaliferi shares many characteristics with Cripple Creek, Colorado, where we have a large project on tellurium geochemistry. In Colorado, prolonged calc-alkaline magmatism was followed by post-subduction, alkaline magmas that produced world-class Au-Ag-Te ores. This PhD will broaden the study to Metaliferi, and work with the Colorado research team to compare and contrast the magmatic evolution of the ore-forming systems in both regions, and to test the crustal recycling hypothesis.
This project contributes to a growing body of work around the world, that consider the lower crust to be an active, dynamic part of arc magmatism during and after subduction, and not an inert fractionated phase.
Funding Notes
This studentship is one of a number of fully funded studentships available to the best UK and EU candidates available as part of the NERC DTP CENTA consortium.
For more details of the CENTA consortium please see the CENTA website: www.centa.org.uk.
Applicants must meet requirements for both academic qualifications and residential eligibility: http://www.nerc.ac.uk/skills/postgrad/
Please direct informal enquiries to the project supervisor. If you wish to apply formally, please do so via: http://www2.le.ac.uk/study/research/funding/centa/how-to-apply-for-a-centa-project
References
Cioacă, Munteanu, Qi, Costin. Trace element concentrations in porphyry copper deposits from Metaliferi Mountains, Romania: A reconnaissance study. Ore Geol Rev 63, 22-39 (2014).
Davidson, Turner, Handley, Macpherson, Dosseto. Amphibole sponge in arc crust? Geology 35, 787–790 (2007).
Harris, Pettke, Heinrich, Rosu, Woodland, Fry. Tethyan mantle metasomatism creates subduction geochemical signatures in non-arc Cu–Au–Te mineralizing magmas, Apuseni Mountains (Romania). Earth Planet Sci Lett 366, 122-136 (2013).
Jenner, O’Neil, Arculus, Mavrogenes. The Magnetite Crisis in the Evolution of Arc-related Magmas and the Initial Concentration of Au, Ag and Cu. J Petrol 51, 2445-2464 (2010).
Smith. Clinopyroxene precursors to amphibole sponge in arc crust. Nat Commun 5, (2014).
Tapster, Roberts, Petterson, Saunders, Naden. From continent to intra-oceanic arc: Zircon xenocrysts record the crustal evolution of the Solomon island arc. Geology (2014).
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