Biography
Gary O’Sullivan is a research assistant in Laser Ablation ICP Mass spectrometry (LA-ICP-MS) in the iCRAGLab @ Trinity College Dublin, who joined iCRAG in early 2017. Gary graduated with a B.A. in Geology from TCD in 2014, and is currently writing up a PhD on the subject of “microanalysis of detrital apatite for use as a provenance proxy” as part of a project separate to iCRAG, in TCD.
Dating and geochemical analysis of uranium-bearing minerals allows us to use them as tracers of the origin of sandstones, as the composition and age of individual sand grains can thus be linked to specific source rocks. By revealing the origin of sandstones we can reconstruct ancient river-systems or even infer the past positions of the continents. My project specifically investigates the mineral apatite for use as a geological tracer. In particular, I investigate the usefulness of apatite versus more established mineral tracers, and I also work to expand our knowledge of how and why the composition of apatite varies in nature.
Project title: Method development in chemical fingerprinting and laser-ablation analysis
Technical description
Detrital geochronometers are used as tracers to determine the source rock provenance of clastic rocks in the geological record, and are therefore useful for tectonic and drainage reconstructions. The mineral apatite (calcium phosphate – Ca5(PO4)3(F,Cl,OH)) is a relative newcomer to the stable of geological tracers, as it has only recently become possible to routinely date by the U-Pb method using LA-ICP-MS.
This project investigates the efficacy and advantages of the detrital apatite U-Pb method for questions of sedimentary provenance, and the novel pairing of this U-Pb data with the trace element geochemical composition of apatite. Apatite is one of the most ubiquitous mineral phases on Earth, crystallising in almost all basement lithologies, and hence is extremely diverse in its composition. By linking this compositional data (which can tell us the source lithology of individual grains) with U-Pb dating, we will be able to establish apatite as a powerful and specific source rock tracer; able to both date the origin of individual grains in sands, and to tell from what kinds of rocks they were derived.
Role
- Specialist Staff
Institution
- TCD
Research Area
- Enabling Methodologies
Expertise
- Geochemistry, Geochronology, LA-ICP-MS Mapping, Provenance, Sedimentology
