Heather Watson
Union College, NY·Earth & Environmental Science
Geologists read the history of Earth from the chemistry locked inside mineral grains. Two zirconium-bearing minerals are especially useful: zircon, a zirconium silicate, and baddeleyite, a zirconium oxide.
- Fields
Earth & Environmental Science
Materials Science
Physics
- Topics
zircon
baddeleyite
diffusion
- Grants
- 1 known grant, through Aug 2027
What they work on
- Measure diffusion rates of key elements in baddeleyite, the zirconium oxide mineral for which almost no diffusion data exist, to constrain how reliably it records isotopic ages and thermal histories.
- Determine diffusion of pentavalent cations in zircon to assess how resistant these potential geochemical tracers are to chemical alteration, and to clarify substitution mechanisms and charge balance for ions of unusual valence.
- Measure xenon diffusion in zircon and baddeleyite to inform interpretation of xenon isotope systematics and noble gas behavior in terrestrial and lunar samples bearing on early Earth and Solar System history.
- Refine accelerator-based ion beam techniques, Rutherford Backscattering Spectroscopy and Nuclear Reaction Analysis, exploiting their fine depth resolution to resolve the very slow diffusivities characteristic of these minerals.
More about the research
They occur in small amounts in most rocks but are tough enough to survive melting, burial and weathering, and zircons include some of the oldest known materials on Earth, carrying information from as far back as 4.4 billion years ago. Their value depends on whether the atoms inside them stay put. If elements diffuse, meaning migrate through the crystal, the ages and chemical signatures they record shift, and interpretations change.
Why it matters
As microanalytical instruments resolve ever finer chemical and isotopic variations in natural samples, interpreting those measurements requires knowing how fast atoms move inside the host mineral. The new diffusion data could let geochronologists and thermochronologists place firmer limits on the timing of geologic events and on the thermal histories of rocks, meteorites and lunar samples. Because zirconia is also used as a refractory and optical material, the property measurements may have technological relevance.
Known grants
From NIH and NSF research grants. Labs often have other funding we can't see.
Closest labs
Johannes Haemmerli
Washington State University, WA·Earth & Environmental Science
Identify which accessory minerals, such as zircon, apatite, allanite and titanite, take part in mineral reactions caused by deformation in granitic rocks, using electron probe microanalysis.
Elizabeth Bell
University of California-Los Angeles, CA·Earth & Environmental Science
Separate the effects of magma depth from those of fractionation, the chemical evolution of magma during crystallization, on trace element ratios in zircon, using zircons from magmas of known melting depth.
Igor Puchtel
University of Maryland, MD·Earth & Environmental Science
Estimate the timing, volumes and proportions of continental and oceanic crust extracted in the Archean, using lead, samarium-neodymium and lutetium-hafnium isotopes in thirteen 3.6–2.7-billion-year-old komatiite-basalt systems.
The school
Union College: 1 labs on PI Pages.
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