This MRI award funds a laser ablation system to couple with an existing Inductively Coupled Plasma Mass Spectrometer (ICP-MS) to enhance geochemistry and solid materials research. The laser ablation (LA) system will allow expanded analytical capabilities and provide new opportunities for PIs. Seven faculty and their students Geology, Chemistry, and Physics will immediately benefit. Currently, in situ and high spatial resolution capabilities are not available at the College; the current ICP-MS only supports solution-based samples. The research agenda bridges several disciplines and the new laser ablation system will support better understanding of: magma mixing using plagioclase trace element analysis, Sr, Ba, Rb, Y, and REE partitioning in plagioclase, trace element thermometry, fission track dating and zircon trace element composition, trace element diffusion profiles as proxies for cooling rate(s), groundwater chemistry as recorded by minerals in dinosaur coprolites using redoxsensitive elements, tropical Andean lake core paleoclimate, barium in mollusk shells - a dual proxy of environmental conditions, laponite/polyaniline nanoassembly analysis, and laser spectroscopy and art conservation. The instrumentation will be used to incorporate research as an integral part of the undergraduate curriculum and to develop innovative, multidisciplinary teaching and research opportunities through the use of state-of-the-art instrumentation. The LA ICP-MS will be integrated into individual faculty research, faculty and student collaborative research activities, and laboratory training exercises in Geology and Chemistry courses at various levels to enrich the undergraduate research experience. The PIs have a strong record of involving undergraduate students in research. Many pursue graduate studies in the sciences and careers in research. Underrepresented groups are actively included in research and educational projects. The LA system will be incorporated into Union?s summer outreach program, which includes youths from disadvantaged and underrepresented backgrounds. Outreach to neighboring institutions will also be made. The LA system will be housed in the current facility supporting the ICP-MS. A sample prep laboratory is adjacent to the ICP-MS lab. Ample facilities and equipment exists for sample prep, storage and processing. The current ICP-MS is 20 years old and has only had 6 months of downtime. The PIs amass over 40 combined years of ICP-MS experience. The PI will use sabbatical to work full-time setting up and preparing the new instrumentation. A dedicated instrument technician will perform routine maintenance. Geology Department funds will be used for service and maintenance. Scheduling will be done on an ad hoc basis originally with an automated system as an option. Training will be conducted by the PIs.
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Project Outcomes The acquisition of the laser ablation system for Union College’s inductively coupled mass spectrometer (LA ICP-MS) has enhanced the research and student opportunities in Geology and Environmental Science. It has allowed us to do in situ analyses of trace elements in several different types of materials, contributing to our understanding of magma chamber processes using crystal chemistry, how age affects the retention of trace elements in zircons, and how trace elements can be used as proxies for environmental conditions in bivalves and speleothems. The LA ICP-MS has also supported Union’s long-standing commitment to incorporate research as an integral part of the undergraduate curriculum and to develop innovative, multidisciplinary teaching and research opportunities through the use of state-of-the-art instrumentation. LA ICP-MS has been integrated into individual faculty research in multiple research areas, as documented below, and has involved collaborators from five other institutions. Ten undergraduates have completed senior theses or summer research projects utilizing the LA ICP-MS and have presented their results at national and regional conferences. In addition, laboratory training exercises have been incorporated into several Geology and Environmental Science courses (~35 students). Research Projects Textural and compositional studies of individual mineral phases allow igneous petrologists to gain new insights into the history of magma chambers prior to eruption. With the LA ICP-MS, we have analyzed trace elements in several different mineral phases in lavas from Volcan Baru, Panama, and tephra deposits from Volcan Tepetiltic, Mexico. The Panamanian lavas show clear evidence of magma mixing, which may have been a trigger for explosive eruptions and subsequent sector collapse. The Mexican pumice samples document a two-phase explosive eruption and very rapid ascension of magma through the conduit, likely driven by melting of a partially solidified magma chamber (Frey et al., 2013). We are currently investigating several explosive deposits in Dominica and the trace element analyses will greatly enhance our understanding of the magma chamber processes and widespread volcanism in the past 100 kyr. Detrital zircon are widely used for provenance and thermal studies of basin strata, and zircons from the Cretaceous Chugach terrane in Alaska were deposited, buried and heated, and then exhumed. This heating caused heterogeneous annealing of fission tracks and our work on zircon chemistry illuminates the controls on annealing. FT analysis of zircon allows for determination of cooling age and uranium [U], and in a new approach we used known U as an internal standard for LA ICP-MS studies. Our data show strong positive correlations between Zr, Hf, Ti and P, inversely correlated with U and Th. HREE elements (Dy and Lu) trend together, however more data are required to investigate this relationship. Reset fission track ages correlate with decreasing U/Th content, and samples with the higher Hf/Dy ratios appear to increase the spread of ages. Ongoing work includes investigating these various correlations in detrital zircons from other terranes and ages. Elements in bivalve shells and speleothems are a potential proxy of environmental and climatic change. We have investigated barium as a proxy of productivity in oyster shells from San Francisco Bay (Goodwin et al., 2013), but were not able to find a clear link between Ba peaks in shells and chlorophyll a peaks (a proxy of phytoplankton abundance). Similarly, uranium in aragonite clam shells did not prove to be a pH proxy as it is in foraminifera and corals, but our research has advanced the possibility of uranium-thorium dating shells by selecting shell regions with high U content (Gillikin and Dehairs, 2013). We have also analyzed several oyster shells that lived through the BP oil spill in the Gulf of Mexico and concluded that the shells did not record the massive spill either because they did not grow during the freshwater diversion and/or the Gulf is already polluted to such a degree that the event was not recorded in the shells (Byrne et al., 2011; Byrne, 2011; Anderson et al., 2011; Roopnarine et al., 2011, 2012). We also investigated freshwater shell elemental chemistry and found sodium can be used as a proxy of road salt contamination in Northeastern streams (O’Neil and Gillikin, 2013), annual cycles in magnesium can be used to determine how long a mussel lived (Spence et al., 2011), and that strontium can be used as a proxy of river discharge (Evans et al., 2012). Finally, a student conducted a preliminary study of a 5300 year old Belgian speleothem to determine if we can use variations in elements to reconstruct past climate (Zeyak, 2012). The data suggest we can use Sr and Ba as proxies of precipitation over the Holocene. Future LA ICP-MS work includes investigations of additional trace elements in freshwater shells of various species and locations.
