"This project aims to provide vital analytical and experimental information that can be used to create models of how the Moon evolved and when it formed. In particular, the project builds on recent advances in determining the ages and compositions of volcanic rocks from the Moon. These new datasets have provided the basis for a preliminary model describing how the interior of the Moon evolved from global ""magma ocean"", into the planetary body that we see today. Ultimately, this model provides a new way to address the question of when the Moon formed. However, the model relies on understanding how radiogenic pairs of elements (for example U and Pb) would have behaved in the early Moon and other rocky planets. Currently, this behavior is poorly constrained. Therefore, a series of high pressure and high temperature experiments have been designed, which will simulate conditions in the ""magma ocean"" period of lunar history. The results of these experiments will then be used to generate new models for the evolution of the Moon and the time of lunar formation.
The importance of this project extends beyond simply lunar science. Firstly, because the Moon provides a more complete geologic record than the Earth (where atmospheric weathering and plate tectonics have erased the earliest terrestrial rocks) studies of lunar rocks have revolutionised more general models describing how rocky planets like the Earth formed. Analogously, this study will produce results that are not just relevant to lunar science, but also to geologic and planetary sciences as a whole, by placing new constraints on models of planetary evolution. Furthermore, the timing of lunar formation is specifically relevant to the Earth, as a giant impact of the type thought to have formed the Moon would have had catastrophic effects on the Earth and its early geologic evolution.
Given that the depletion of Pb in lunar rocks has previously been attributed to loss of volatile elements very early in the Moon’s history, this work will also provide new insight into the lunar volatile element budget. By understanding the potential effects of U and Pb partitioning during lunar core formation and magma ocean crystallisation, we will have clearer knowledge of how volatile depleted the Moon would have needed to be, in order to explain the Pb isotope data acquired from lunar samples. The topic of lunar volatiles has been subject to a surge of interest in the last decade, with multiple new studies being published in high-profile journals. It is also a subject with a clear interdisciplinary link to astrobiology, given that volatiles (and specifically water) are fundamental to life as we know it, so it is vital to understand the behaviour of volatile elements and compounds during the formation of planetary bodies.
Finally, the behaviour of elements during metal-silicate segregation that will be studied here is also important in the steelmaking industry, and the host institution has strong links with the R&D division of Tata Steel, who are interested in the behaviour of Pb in particular.
The key objectives of this project are as follows:
- continued analysis of lunar samples, resulting in the production of a complete set of ages and Pb isotopic compositions of the main types of basalts sampled during the Apollo missions
- completion of high-pressure/temperature experiments in order to better constrain silicate/melt partitioning behavior for a range of radiogenic parent-daughter pairs
- combining experimental and analytical datasets to produce a revised model for the Moon's early magmatic evolution, and place new constraints on the age of the Moon"
