Our research is currently supported by the Science and Technology Facilities Council, the UK Space Agency, Carnegie Trust, European Commission, Royal Society of Edinburgh and Barringer Family Fund for meteorite impact research. We are currently working across three areas:

1. Early solar system evolution

2. History of the atmosphere, lithosphere and biosphere of Mars

3. Earth impacts

Research Funders

Early Solar System Evolution

We seek to understand the processes and chronologies of assembly and evolution of asteroids by microtextural, chemical and isotopic analysis of chondritic meteorites. Topics of current interest are described below.
Multiphase calcite crystals in a CM2 meteorite

Aqueous alteration of the CM carbonaceous chondrites

The CM carbonaceous chondrites are samples of C type asteroids. Their primitive bulk chemical composition suggests that they have changed little since accretion at the birth of the solar system, yet these rocks contain abundant phyllosilicates and carbonates that have formed in asteroidal interiors by the action of liquid water. The focus of our work is on understanding the processes and chronologies of water-rock interaction via petrographic and isotopic (16,17,18O; 53Mn-53Cr, 39Ar-40Ar) analysis of fine-grained carbonate- and phyllosilicate-rich meteorite matrices. We are also studying meteorite petrofabrics using X-ray computed tomography, and the mineralogy of pristine chondrules.

Timescales for cooling of the H-chondrite parent body

The early solar system was a turbulent and violent place, with a complex interplay between numerous processes including radioactive heating, thermal diffusion, and massive impact events. Knowledge of the timescales and prevalence of such processes is crucial to understand the formation of the rocky planets and asteroids. In this study we are investigating the cooling history of the H chondrites – the most common type of meteorite. In particular, we aim to determine if cooling was consistent with heat diffusion only (the onion-skinned model), or if cooling was enhanced, for example, via excavation by impacts.

History of the atmosphere, lithosphere and biosphere of Mars

The exploration of Mars is a priority for national space agencies. Our contribution is to enhance understanding of the history of the crust, atmosphere, and potentially the biosphere of Mars by analysis of meteorites, characterisation of terrestrial analogues, and by construction of instruments for future Mars rovers. Topics of current interest are described below.

Shergottites: from old Mars or young Mars?

How old is the surface of Mars? The bulk of the red planet is heavily cratered, indicating ancient terranes exposed for more than 3 billion years. In contrast, the majority of martian meteorites (the shergottites) apparently have much younger ages as recent as 180 million years ago. We aim to develop a robust chronology to allow for investigation of this shergottite age paradox¹, and to understand the chronology of martian meteorites within the broader context of martian geology.

Water-mediated alteration of the nakhlite meteorites

The nakhlite group of martian meteorites are a very important tool for understanding the evolution of the planet’s hydrosphere. They contain a suite of minerals that crystallized from liquid water ~600 million years ago, and we are working to unravel the sequence in which these minerals formed in order to develop and refine models of interaction of crustal water with the igneous crust of Mars.

Martian carbon in the Tissint meteorite

We are using a wide range of analytical techniques to distinguish between indigenous Martian carbon and terrestrial contaminants in Tissint (the most recent, most pristine Martian meteorite). The overall aim is to assess whether any native carbon present is of biotic or abiotic origin, and therefore whether Mars could have been (or could currently be) capable of supporting life.

Astrobiology and the habitability of Mars

Knowledge of the longevity of organic molecules at the martian surface is crucial for designing strategies for planetary exploration. To this end, we are using the Chilean Altiplano as an analogue for Mars, and it is a particularly appropriate site because it has low temperatures and a high flux of UV radiation.

History of volatiles in the martian atmosphere and crust

There are currently more than 60 martian meteorites in various geological collections on Earth. In general, these meteorites are volcanic rocks (basalts) that crystallized from Mg- and Fe-rich magmas derived from depth in the planet’s interior. These magmas erupted onto the martian surface as lava flows, or intruded into the shallow sub-surface. Based on their chemistry and mineralogy, the martian meteorites can be separated into groups, where each group originates from a different site on Mars and was formed at a different period in martian history. Our research is focused on investigating the volatile element (e.g., H, F, Cl) content of both primary and secondary minerals in martian meteorites at sub-micrometre scales. These investigations will indicate the abundance of volatile elements in the martian interior, and will clarify the cycling and eventual fate of these elements at the martian surface. Knowing the stability and fate of the martian atmosphere is key to understanding whether life developed on Mars.

Development of instrumentation for Mars rovers

Rovers have proven to be very powerful tools for understanding the nature and composition of the martian surface, and new rovers are being designed. We are designating new instruments for radiometric age dating of crustal rocks, and for machining the surfaces of rocks in order to understand better their mineralogy and internal structure.

Earth impacts

The impact of extraterrestrial rocks on the Earth’s surface has been of pivotal importance in the history of life on Earth, but also in other processes such as the formation of economically important mineral deposits. We seek to understand better the timescale of Earth impacts, the potential for them to drive hydrothermal mineralization and their possible role in biological evolution. Current areas of research include:

Post-impact hydrothermal alteration of the Rochechouart impact crater

Another important process which is being utilized in decoding the history of volatiles on Mars is impact cratering. On tectonically dead terrestrial bodies, impacts provide an exogenic source of heat, which when combined with even small amounts of hydrous mineral phases or ice, has the potential to initiate hydrothermal activity. Impact sites on Earth are being explored and assessed for habitability in hopes to provide insight to potential exploration sites on Mars and other rocky, hydrous bodies in our solar system.

The Triassic Wickwar ‘tektite’ bed

A layer of sedimentary rock containing millimetre-sized spheres of glauconite occurs in Triassic rocks of south-west England. These spheres are believed to have formed by replacement of tektites, which are beads of glass produced by terrestrial meteorite impacts. We are currently examining these rocks to understand better the nature of their target rock, and the diagenetic history of the deposit.

Using feldspars to probe the nature of impact craters

Feldspars are one of the most common minerals in the Earth’s crust and so have the potential to be used to provide detailed information on geological processes, including impact cratering. However, the process of cratering disrupts the crystalline structure of the mineral, compromising its use to date impacts. In this project we are investigating the effects of impacts on alkali feldspars, and whether they can be used to determine the chronology of impacts throughout Earth history.