My research centres around the application of ion microprobes to the understanding of the isotopic nature of materials at the microscale. This type of technology allows analyses of materials with high degrees of selectivity and is applied to the characterization of provenance of dust grains in the early solar system, through to the provenance and origins of rocks from Gondwana. Current interests include analysis of refractory meteorite components for evidence of the characteristics of the solar nebula, 4-isotope sulfur compositions form terrestrial and extraterrestrial samples, and 3-isotope oxygen analyses from meteorites and their components.

Annual Report 2014:  Development of SHRIMP SI

SHRIMP SI continues to expand its retinue of stable isotope applications.  The past year saw the first results reported for oxygen-three-isotope analysis of meteoritic materials, with 16O excesses in refractory inclusions, the solar system’s oldest materials (Sapah et al. 2014), and 16O deficits in interstitial silicates in chondrules (Bridges and Ireland, 2014). Sulfur-four-isotope analysis of sulfides and sulfates has been developed to a near-routine capability. The four isotopes of sulfur fractionate differently between Archean photochemical reactions and biochemical reactions, allowing the possibility of discerning early life processes on Earth. Development of charge-mode acquisition (Ireland et al. 2014) allows faraday cup measurements of count rates down to 50,000 c/s and work continues to lower this noise limit by an order of magnitude or more.  This capabilitywill allow the measurement of isotope ratios that normally require the use of electron multipliers, which can be compromised by gain drift and dead time corrections. Ultimately this will lead to the development of a new multiple collector for SHRIMP SI, as well as SHRIMP II.

 

References:

Ireland et al. (2014) Oxygen isotope compositions of CAI from NWA4502 CV3 chondrite. 45th Lunar and Planetray Science Conference,  Abstract #1671.

Bridges and Ireland (2014) Oxygen isotope exchange in OC chondrules.  77th Meteoritical Society Annual Meeting, Abstract #5334.  

Ireland et al. (2014) Charge-mode electrometer measurements of S-isotopic compositions on SHRIMP-SI.  Int. J. Mass Spectrometry 359, 26-37.