The Elemental and Isotopic Partitioning Behavior of Nitrogen During Magmatic Differentiation

Nitrogen is the dominant element in Earth's atmosphere at 78% by mass. It is a core element to our DNA, it is an essential nutrient for life and is a crucial ingredient to form the building blocks for life. Yet, we know little about how earth's atmosphere came to be so nitrogen rich, and how nitrogen moves between earth's reservoirs. These questions are still a topic of debate, and the answers have great implications to our understanding of Earth's elemental fluxes, evolution of our atmosphere, evolution of life on earth, and how other planets differ to our own.

Due to the wide range in valency of nitrogen, nitrogen can form a variety of species (e.g. N2, nitride, nitrate, ammonium, ammonia, etc) under different geochemical conditions. Many of these nitrogen species behave very differently in silicate Earth, with different compatibilities, charges, volatility etc. Due to their wide range of traits, they can substitute for many similar ions in the crystal lattice of common minerals in the crust and mantle. Therefore, we must better constrain how nitrogen behaves in silicate earth, and what factors affect its behaviour, to understand how nitrogen occupies, and moves through, our planet.

This project aims to identify the behaviour of nitrogen under different geochemical conditions: specifically, its elemental and isotopic partitioning behaviour during magmatic differentiation. A range of alkaline and subalkaline rocks from volcanic and plutonic settings will be analysed to speak to the behaviour of nitrogen atoms and isotopes under different tectonic and geochemical conditions. The samples will show a variation in P-T-X-fO2 conditions during formation and the research results should therefore be able to speak to the effect of each of these parameters on the behaviour of nitrogen.

Specific findings are expected to include: the source of nitrogen in investigated igneous systems; the key controlling factors on nitrogen behaviour; the elemental and isotopic partitioning behaviour of nitrogen as igneous systems evolve, how nitrogen partitions between key silicate minerals within an evolving system, and how volcanic degassing of nitrogen is influenced by igneous differentiation.