This award provides $11,840 in NSF funding over 12 months to acquire an EDS spectrometer which uses Silicon Drift Detector (SSD) technology. The current detector uses an older technology which makes analyses very slow relative to the requested detector and carries additional costs for consumable liquid nitrogen. Duke and UNC will support half the unit cost. The new detector will be used for Earth and materials sciences at UNC and Duke. Science to be undertaken with the new detector will involve study of volatiles and volatile-rich fluids during interstitial fluid crystallization, the textural evolution of layered intrusions, plutonic petrogenesis and growth, detrital zircon transport, mineralogy, oceanic basalt geochemistry, and paleoclimatology and paleoceanography. The facility supports a wide range of petrographic, geochemical and environmental research interests at Duke and the UNC, as well as other colleges and universities in North Carolina. The new detector will be incorporated into courses to both undergraduate and graduate students in geosciences. Two non-working spare instruments are on hand for obtaining outdated parts. The instrument will be maintained by the PI. The PI will also train new users. The upgraded instrument is not expected to require any more support than currently needed.
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. All funding was used to purchase a 4Pi silicon drift detector (SDD). This piece of equipment allows for the rapid acquisition of sample composition on a micron scale by the use of energy-dispersive spectrometry. It also allows one to produce composition maps on the 10-1,000 micro scale about an order of magnitude faster than we could previously. To date the new instrument has been used in three main areas of research: 1) Characterization of trace phases in the Stillwater Complex of Montana. The Stillwater Complex is host to an important deposit of the platinum-group elements (PGE) associated with sulfides, for which magmatic fluids have been suggested to be the transporting agent. Work with the new instrument has shown that these sulfides are local associated with a high temperature (~900 °C) carbonates and chlorapatite, supporting models of transport by carbonatitic-Cl fluids. 2) Characterization of arsenic-bearing phases in groundwater aquifers. Arsenic and other heavy metals are a potential health hazard in groundwater. The new instrument allows one to quickly identify possible trace minerals that are possible sources of arsenic contamination. 3) Characterization of heavy metal phases in coal. As with groundwater, heavy metals in coal are a potential source of groundwater contamination and, when burned, airborne contamination as well. The new instrument has been used in preliminary studies of heavy metal minerals in Pennsylvania coal deposits.
