Isotope and Trace Element Cosmochemistry
My research is largely the application of mass spectrometric techniques to unravel the trace element and isotopic histories of meteoritic material.
Meteorites are the only objects that we can handle that come from outside the Earth-Moon system. Many are survivors from the very earliest days of the Solar System and, as such can give us clues as to how planets, planetary systems and stars form and evolve. However these rocks have complex nebular and parent body histories and so we need to deconvolve these separate processes before we can understand their formation and what they can tell us about the first few million years of Solar System history.
I use mass spectrometric techniques to unravel the trace element and isotopic compositions of chondrules, calcium- aluminium-rich inclusions (CAIs) and other components of primitive chondritic meteorites as these were probably the earliest formed solids in the Solar System. However we know little about how, where and when they actually formed and how they relate to other objects in the Solar System.
Equipment at the University of Maryland allows me to indulge in trace element and high precision isotopic analysis of extraterrestrial materials. Whilst I am involved in most of the analyses carried out in the plasma lab, at the moment I am working with collaborators on:
(i) Nb-Ta and REE distributions in CAIs and chondrules to trace the distribution of CAIs in the early solar system.
(ii) Nb in iron meteorites to find the fate of Nb in the Earth.
(iii) REE abundances in CAIs and chondrules.
(iv) Light element distributions in CAI analogues
(v) Siderophile distributions and abundances in iron meteoritesJust as there are many elements so there are many methods for measuring their abundances and isotopic ratios. In the past I have used stepped combustion, coupled with gas source mass spectrometry, for the analysis of carbon, nitrogen and hydrogen isotopes. This I applied to the analysis of organic material in carbonaceous and ordinary chondrites, and presolar grains from a variety of primitive meteorites in order to help understand their origins and evolution. Gas source mass spectrometry has also enabled me to use Ar-Ar and I-Xe dating to look at the history of Martian meteorites and chondrules from ordinary and enstatite chondrites. By coupling gas source mass spectrometry with laser fluorination I have measured oxygen isotopes in chondrules and CAIs from ordinary and carbonaceous chondrites and olivine and pyroxene in ureilites, primitive achondritic meteorites.