FOR 2881:  Diffusion Chronometry of magmatic systems

• Subject Area: Geosciences
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 405665352

Geological processes occur in and on the Earth over a range of timescales that form a nested, hierarchical structure. Determining the durations of processes that occur on the shorter end of this time-spectrum has been a challenge. The tools of diffusion chronometry have emerged as a very promising method to provide solutions in many situations. High temperature magmatic systems provide an excellent natural laboratory for developing and calibrating these tools because various kinds of observations from monitoring volcanoes are able to provide cross checks on the results. Subsequently, the newly developed and refined tools may then be applied to a much wider range of geological and planetary settings. This project aims to bring together field geologists, experimental scientists, theoreticians and modellers from geosciences as well as neighboring fields of physics and materials science to advance this development. Some of the main objectives of the first phase of the proposal for this research unit were: the measurement of missing diffusion parameters in pyroxenes and plagioclase, exploring the recently discovered role of isotopic fractionation at high temperatures due to diffusion, calibrating phase relations to enable the setting of boundary and initial conditions in high resolution diffusion models, exploring the role of textural evolution, and field tests in a divergent as well as at a convergent plate margin magmatic setting (Oman and Kamchatka, respectively). These were to be accompanied by the development of user-friendly codes that incorporate the advances. In the second cycle the overall objective remains the same while the projects extend and build upon the new developments that were made in the first cycle of funding. Experimental projects to measure missing diffusion coefficients in pyroxenes, amphiboles (for the first time) and spinels are planned, isotopic fractionation during diffusion in a range of minerals (pyroxenes, feldspars, spinels) and elements (Fe, Mg, Li) are planned, phase equilibria experiments extend to alkaline systems, with a view to applications and field testing in the Eifel region. Development of user-friendly software and textural modeling using phase field methods will build on algorithms developed in the first phase.

• DFG Programme: Research Units
• International Connection: Belgium, United Kingdom

Projects

• Amphibole stability and chemistry in mafic calc-alkaline and alkaline magmas (Applicants Holtz, Francois ;  Marxer, Felix )
• Application of phase-field simulation of solidification and texture evolution to diffusion chronometry (Applicant Kundin, Julia )
• Chronometry in plutonic rocks: cooling rates of ancient oceanic crust (Applicants Faak, Kathrin ;  Kirchenbaur, Maria )
• Coordination Funds (Applicant Chakraborty, Ph.D., Sumit )
• Diffusion-driven isotope fractionation in feldspars, chain silicates and oxides (Applicants Oeser-Rabe, Martin ;  Weyer, Ph.D., Stefan )
• Diffusion in common mineral phases. Part 3: Chain silicates: pyroxene and amphibole (Applicants Dohmen, Ralf ;  Holtz, Francois )
• Diffusion in common mineral phases. Part 4: Spinel (Applicant Chakraborty, Ph.D., Sumit )
• Large Scale Artificial Intelligence Augmented Mineral Analysis (LS-MAIner) – characterization of volcanic rocks for diffusion chronometry (Applicants Almeev, Ph.D., Renat ;  Sester, Monika )
• Timescales of processes in magma mush zones – a case study from Pulvermaar, Eifel Volcanic Field, Germany (Applicants Chakraborty, Ph.D., Sumit ;  Weyer, Ph.D., Stefan )
• User friendly codes for the generalized application of diffusion chronometry (Applicant Chakraborty, Ph.D., Sumit )

• Spokesperson: Professor Sumit Chakraborty, Ph.D.