The Elemental and Isotopic Partitioning Behavior of Nitrogen During Magmatic Differentiation

氮是地球大气中的主要元素，占总质量的78%。它是我们DNA的核心元素，是生命必需的营养物质，是构成生命基石的关键成分。然而，我们对地球大气是如何变得如此富含氮的，以及氮是如何在地球的储存库之间移动的知之甚少。这些问题仍然是一个争论的话题，其答案对我们理解地球的元素通量、大气的演化、地球上生命的演化以及其他行星与我们自己的行星有何不同具有重大意义。由于氮的价态范围广，在不同的地球化学条件下，氮可以形成多种物质（如N2、氮化物、硝酸盐、铵、氨等）。这些氮的许多种类在硅酸盐土中表现得非常不同，具有不同的相容性、电荷、挥发性等。由于其广泛的特性，它们可以替代地壳和地幔中常见矿物晶格中的许多类似离子。因此，我们必须更好地约束氮在硅酸盐土中的行为，以及影响其行为的因素，以了解氮是如何占据并穿过我们的星球的。本项目旨在确定不同地球化学条件下氮的行为，特别是在岩浆分异过程中氮的元素和同位素分配行为。将分析一系列来自火山和深部构造环境的碱性和亚碱性岩石，以说明不同构造和地球化学条件下氮原子和同位素的行为。样品将显示在形成过程中P-T-X-fO2条件的变化，因此研究结果应该能够说明这些参数对氮行为的影响。预计具体的发现包括：所研究的火成岩系统中氮的来源；氮素行为的关键控制因素；随着火成岩系统的演化，氮的元素和同位素分配行为，在演化系统中氮如何在关键硅酸盐矿物之间分配，以及火成岩分异如何影响氮的火山脱气。

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.