Postdoctoral Researcher/Experienced Postdoctoral Researcher Numerical modelling of PGE mineralising processes

Numerical modelling of PGE mineralising processes

Job title: Postdoctoral Researcher/Experienced Post Doctoral Researcher

Location: Discipline of Geology, School of Natural Sciences, Museum Building, College Green, Dublin 02, Ireland

Mentors: Dr Mike Stock (Trinity College Dublin; PI), Prof. Christian Huber (Brown University), Prof. Marian Holness (University of Cambridge)

Salary: Appointment will be made on the appropriate point of the SFI Level 2A or 2B Team Member salary scales, depending on experience, i.e., €41,208 - €53,092 gross per annum.

Post duration: 2 years, fixed term

Hours of work: 37.5 per week

Application closing Date: Midnight Dublin time, 11 October 2023

Position start date: 1 December 2023 (or as soon as possible thereafter)

About the project

Platinum group element (PGE) deposits occur in both layered mafic intrusions (e.g. the Bushveld Complex, South Africa) and magma conduits (e.g. Norilsk, Russia), but require specific thermodynamic and fluid mechanical conditions. Specifically, mineralisation occurs through the segregation, metal enrichment and physical accumulation of sulphide liquids in mafic and ultramafic magmatic systems (Naldrett, 2004). While the chemical processes leading to sulphide liquid saturation have been extensively explored through geological observations and laboratory experiments (e.g. O'Neill & Mavrogenes, 2002), fluid mechanical controls on mineralisation remain poorly constrained, with few studies unifying the thermal, physical and thermodynamic constraints on PGE deposit formation.

In contrast, the chemical and physical dynamics of sub-volcanic systems are relatively well understood, particularly with respect to the behaviour of aqueous fluids. Major insights in the past decade have arisen from the development of numerical models which accurately describe their thermal evolution during magma intrusion (Karakas et al., 2017), the conservation of enthalpy and mass during assimilation/fractional crystallisation, metal partitioning between melts and migrating fluids (Huber et al., 2012), and three-phase separation in porous media (Huber & Parmigiani, 2018). While these have not been widely applied to understand intrusive ore-forming processes, comparable modelling approaches hold great potential for understanding mafic and ultra mafic mineralisation.

This project will adapt existing thermal, thermodynamic and fluid mechanical models developed for interrogation of sub-volcanic processes to include constraints on sulphide solubility, the physical and wetting properties of sulphide liquids, and silicate-sulphide PGE exchange. Specifically, the project will aim to:

• Understand how intrusion cooling history impacts assimilation and sulphide saturation through thermodynamic models describing crustal thermal evolution, the propagation of assimilation fronts, assimilation fractional crystallisation and sulphide solubility.
• Model PGE-enrichment in sulphide liquids migrating through magma mush by adapting 1D models of aqueous fluid migration in magmas to include the physical properties of sulphide liquids and thermodynamics and kinetics of silicate-sulphide PGE exchange.
• Understand the physical transport and accumulation of sulphide liquids in intrusions with variable crystallinities by adapting models of three phase aqueous fluid-melt-crystal kinetics.

Models will be refined using petrological observations of natural systems and will initially be applied to understand ore-forming processes in well-constrained global case studies (e.g. mineralised intrusions in Norilsk and Skaergaard, and potentially mineralised intrusions in Ireland). They will then be run over a range of parameter space (e.g. cooling rate, intrusion volume, magma/assimilant composition) to isolate the dynamic variables that facilitate PGE mineralisation globally.

This postdoctoral position forms part of the SFI-GSI co-funded Critical-Ireland project. The successful applicant will be based in Trinity College Dublin but will undertake a research visit to Brown University (USA) for training in specific modelling techniques. The postdoc will work closely with other members of the Critical-Ireland team to integrate their results and achieve the projects broad objective of understanding the fundamental magmatic processes which generate PGE mineralisation. Results will be communicated to industry through the iCRAG consortium.

We seek an enthusiastic and motivated individual to undertake this project. The applicant should have a strong background in Earth science, physical sciences or applied mathematics, including a PhD in a relevant subject. The applicant must be able to demonstrate the high level of numerical competency required to undertake this research, preferably with prior experience in computational fluid mechanics (CFD). A research background in igneous systems is desirable but not essential.

For all enquiries, please contact Dr Michael Stock, Michael.Stock@tcd.ie.

Application procedure

To apply, the following documents should be submitted to Michael.Stock@tcd.ie in advance of the closing date:

• A cover letter, outlining the applicants experience and motivation for undertaking this project (max. 2 A4 pages).
• A research statement, outlining the applicants specific skillset(s) and academic preparation with regard to this project (max. 1-2 pages).
• The applicants CV.
• Two academic references (these can either be submitted by the applicant or confidentially by the referees).

Shortlisted applicants will be invited to interview in October 2023 and will be informed of the outcome within one week. The project start date is 1 December 2023 (or as soon as possible thereafter by negotiation).

Funding notes

This postdoctoral position is fully funded for 2 years by a Frontiers for the Future Project grant, supported by Science Foundation Ireland and Geological Survey Ireland. Applicants require the right to work within the European Union in advance of the start date.

References

• Naldrett, A. J. (2004). Magmatic sulfide deposits: Geology, geochemistry and exploration. Springer, Heidelberg, Germany.
• O'Neill, H.C., and Mavrogenes, J.A. (2002). The Sulfide Capacity and the Sulfur Content at Sulfide Saturation of Silicate Melts at 1400°C and 1 bar. Journal of Petrology, 43, 1049.
• Karakas, O. et al. (2017). Lifetime and size of shallow magma bodies controlled by crustal-scale magmatism. Nature Geoscience, 10, 446.
• Huber, C. et al. (2012). A physical model for metal extraction and transport in shallow magmatic systems. Geochemistry, Geophysics, Geosystems, 13, Q08003.
• Huber, C. & Parmigiani, A. (2018). A physical model for three?phase compaction in silicic magma reservoirs. Journal of Geophysical Research: Solid Earth, 123, 2685.