This award supports continued operation of the CAMECA /ims 1270 /high transmission, high resolution ion microprobe at UCLA as a national facility for isotopic microanalysis of geologic materials. Research will continue to focus on dating geological samples at high spatial resolution but new thrusts in biogeochemistry and environmental proxy records investigating, among other issues, climate change, are being pursued. We expect to host over 50 external investigators representing about half as many independently supported NSF projects. Technical upgrades, both hardware and software, are planned for the coming three year funding cycle. NSF funds provide us a stable source of support to develop the new analytical protocols that will help us better understand the Earth and our place in it and allow us to host scientists from across the nation who benefit from access to our world-class ion microprobe laboratory. In addition to this direct benefit to the community, interactions between visiting scientists and students with UCLA staff tend to catalyze and incubate new ideas that feedback into our discipline. As one of only a handful of similar facilities world-wide, we are one of the principal sources of trained personnel to commission new ion microprobe laboratories in the field of geo- and cosmochemistry. In this regard, we will host an annual Workshop in which two dozen or so young scientists are brought to UCLA for a week of lectures and laboratory demonstrations to introduce the next generation to the potential of the ion microprobe in the geosciences.
This grant subsidizes the costs of laboratory operation thereby enabling us to provide external user access to a high resolution, high sensitivity ion microprobe. Our dual role is to innovate new analytical methods for microscale isotopic analysis and enable access to these capabilities for the wider community. We have continually improved our CAMECA ims1270 to the extent that very few components remain unmodified from the as-delivered prototype instrument. We have long established protocols for the routine measurement of U-Th-Pb in zircon, monazite, and baddelyite as well as stable isotope ratio analysis B, C, N, O, Mg, Si, and S and continue to provide these capabilities. In the project funding period, we developed U-Th-Pb and oxygen isotope analysis of rutile to take advantage of the higher intrinsic sensitivity relative to LA-ICPMS to provide accurate in situ methods to date mafic dykes and intrusions. We developed negative ion analysis of apatite to take advantage of the higher brightness and smaller lateral spot dimensions available to our Cs+ and Ga+ ion sources. We used the ion imaging mode to re-calibrate the zircon thermometer, producing a superior and more precise model. Interestingly, we found no observable pressure effect to 25 kbars and no effect of water activity. Chemical and isotopic signatures in marine carbonates have been used to infer aspects of past climate, but the interpretation of such data is often not straightforward. In addition to temperature, seawater chemistry and mineral growth rates can cause systematic changes in proxy records. We experimentally calibrated geochemical tracer uptake in carbonates in order to improve interpretations of coral records for reconstructing ocean chemistry changes. Lastly, we began to develop a new role for the NASA-funded MegaSIMS – an ion microscope mated to a million-volt tandem accelerator – to be a unique complementary capability to our "conventional" SIMS. Our first application development was to take advantage of the molecule-free secondary ion beam to pursue both U-series geochronology and nuclear forensic applications. We hosted three annual Ion Microprobe Student Workshops in which we bring over 20 graduate students to UCLA for five days of lectures and practical demonstrations. The lectures focus on the role of SIMS in geology and geochemistry with hands-on demonstrations of the UCLA ims 1270 ion microprobe and its auxiliary facilities by the facility's researchers and faculty. Data from our facility was used in 18 graduate student theses over the three year funding period. Several students were hosted for multi-month periods while they used the ion microprobe and other UCLA resources. During this grant period, we logged the most instrument usage since we began to automatically record user time in 1999 (typically 13.7 hours/day on a 365 day/year basis). This reflects both the absence of any major repairs and the presence of a particularly enthusiastic group of post-docs and PhD students (one of the latter logging 250 hours). Between 2010 and 2013, the percentage of total usage for NSF-funded research was 29.4%.
