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Magmatic mass transfer through deep crust: Field relationships, chemistry and rheology

Dr Sandra Piazolo (SEE), Dr. Thomas Mueller (SEE), Assoc. Prof. Nathan Daczko (Macquarie)

Project partner(s): Department of Earth and Environment, Macquarie University, Australia (CASE)

Contact email: s.piazolo@leeds.ac.uk

Summary

This exciting project aims to shed light on the long standing problem of how melt is transferred through the crust by a combination of field studies in Greenland and Central Australia, combined with lab-based microstructural and geochemical analyses. Depending on student’s interests investigations will be augmented by a choice of high temperature or analogue experiments and/or numerical modelling. The student will be part of an international research group involving partners and students based in Greenland, Australia and Italy. Throughout the studentship, the student will have the opportunity to visit partners.

Fluids are instrumental in the evolution of Earth’s crust and mantle; they facilitate chemical exchanges that change basic rock properties and are important for crustal differentiation at the large scale. Fluid advection of heat and mass is central to nuclear waste storage, CO2 sequestration, geothermal systems, and the formation of ore deposits. 

The motivation for examining transfer of melt in the lower crust is rooted in a fundamental gap in our knowledge. It is poorly understood how magmatic mass transfer occurs through the deep crust. This project builds on observations that significant migration of melt and mass transfer at the kilometre-scale can occur in localized areas resulting in significant changes to both the melt and the host through which melt migrates (Daczko, Piazolo et al. 2016) (Fig. 1).

This project aims to achieve a new level of understanding and quantification of the underlying principles governing magmatic mass transfer through deep crust. Three main questions will be addressed:

1) Processes: What physiochemical processes are involved in magmatic mass transfer through deep crust? 

2) Recognition: How can geologists recognize prior magmatic mass transfer in natural rocks? What is the physical and chemical fingerprint at micro- to meso-scales? Do rock units commonly mapped as metasediments in fact represent such melt transfer zones which developed through extreme metasomatism?

3) Effect: How does magmatic mass transfer affect the chemistry, geochronology, melt fertility and rheology (strength) of the crust it transfers through as well as the crust it forms at higher levels?

In this project, you will work with leading scientists at Leeds, UK, and the Centre of Excellence, (Macquarie University, Australia), together with experts on the geology of the field areas to develop an in-depth understanding of how melt moves through the crust and how such melt flux influences the chemical make-up of both the transgressing melt and the material that the melt passes through. Special emphasis will be given to the feedback between deformation and melt migration.

The studentship will involve 

(1) field work in remote areas of W. Greenland and/or Central Australia. 

(2) In-depth analysis of samples from the chosen two field areas. This will include chemical analysis including major and minor elements, bulk rock geochemical analysis, quantitative microstructural analysis (e.g. Smith et al. 2015) and high resolution trace element analysis using synchrotron analysis

In order to develop an in-depth understanding of the processes involved, the student will be able to utilize additional tools, the choice made depending on the student’s individual background and interests:

1. Numerical modelling of reactive flow 

2. High temperature- high pressure experiments 

3. Analogue modelling with real-time analysis (see for example Bons et al. 2001, 2008)

4. Trace element analysis using laser ablation and synchrotron techniques (Stuart et al. 2016)

5. Analysis of “nanogranitoids” – crystallized melt inclusions (e.g. Bartoli et al. 2016)

You will work under the supervision of Prof. Sandra Piazolo and Dr. Thomas Mueller within the IGT metamorphic and structural geology group.  This project provides a high level of specialist scientific training in: (i) Field work and targeted sampling in lower crustal sections, (ii) state-of-the-art analytical techniques with special emphasis on both chemical and structural analysis of geomaterials; along with a selection of other skills including numerical modelling of reactive flow, high temperature and pressure experiments and analogue modelling. You will visit the Centre of Excellence “Core to Crust Fluid Systems” (CCFS, Macquarie University, Australia) for an extended period. In Australia you will work under the supervision of Assoc. Prof. Nathan Daczko. 

Click here for a full project description.

References

Bons, P. D., Elburg, M. A. and Dougherty-Page, J. (2001). Journal of the Virtual Explorer, 4.

Bons, Paul D., et al. (2008) Geology 36, 851-854.

Daczko, N.R., Piazolo, S., Meek, U., Stuart, C.A. and Elliott, V. (2016), Scientific Reports, 6, 31369, doi:10.1038/srep31369.

Stuart, C.A., Piazolo, S. and Daczko, N.R. (2016), Geochemistry, Geophysics, Geosystems (G3), doi: 10.1002/2015GC006236.

Smith, J. R., Piazolo, S., Daczko, N. R., & Evans, L. (2015). Journal of Metamorphic Geology, 33, 557-577.

 

Related undergraduate subjects:

  • Chemical engineering
  • Earth science
  • Geochemistry
  • Geological science
  • Geology
  • Geoscience
  • Materials science
  • Physical science