TY - JOUR
T1 - Analyzing nitrogen in natural and synthetic silicate glasses by secondary ion mass spectrometry
AU - Regier, Margo E.
AU - Hervig, Richard
AU - Myers, Madison L.
AU - Roggensack, Kurt
AU - Wilson, Colin J N
N1 - Funding Information:
Editorial handling by Dr. David Hilton and two reviews by Dr. Gary Huss and an anonymous reviewer are gratefully acknowledged. We thank Dr. John Stix and Dr. Gregor Lucic at McGill University for providing FTIR spectra for the rhyolitic glasses, Dr. Kenny Befus for providing FTIR-analyzed inclusions, Dr. Paul Wallace for providing suggestions and inclusions, staff at Menlo park for assisting in data collection, and Dr. Michael Rowe who provided Taupo samples. Dr. Alex Navrotsky at UC Davis is also thanked for providing samples of oxynitride glass. This work was supported by the Mineralogical Society of America's Student Grant in Mineralogy and Petrology and the NSF grant EAR1362996 to the Arizona State University Secondary Ion Mass Spectrometry Facility.
Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2016/12/30
Y1 - 2016/12/30
N2 - Volatile releases through volcanic eruptions are one of the major processes contributing to the global nitrogen cycle. Past studies have often estimated the magnitude of this flux using volcanic emission measurements, which are limited to currently active systems and sensitive to atmospheric contamination. Another possible approach is the measurement of nitrogen in melt inclusions, which are parcels of magmatic melt trapped prior to eruption. This methodology requires appropriate analytical parameters for nitrogen analysis in silicate glasses by secondary ion mass spectrometry (SIMS), which have not yet been established. To this end, calibrations for nitrogen were obtained using ion implanted basaltic and rhyolitic glasses. We demonstrate that water content significantly affects the ion yields of 14N + and 14N16O −, as well as the background intensity of 14N + and 12C +. Application of implant-derived calibrations to natural samples provide the first reported concentrations of nitrogen in melt inclusions. These measurements were made on samples from the Bishop Tuff in California, the Huckleberry Ridge Tuff of the Yellowstone Volcanic Center, and material from the Okaia and Oruanui eruptions in the Taupo Volcanic Center. In studied material, we often find maximum nitrogen contents of less than 45 ppm and that nitrogen concentration varies positively with CO2 concentration, which reflects a partial degassing trend. Using the maximum measured nitrogen contents for each eruption, we find that the Bishop released >3.4 × 1013, the Huckleberry Ridge released >1.4 × 1014, the Okaia released >1.0 × 1011, and the Oruanui released >4.5 × 1013 g of nitrogen. Simple calculations suggest that with concentrations such as these, rhyolitic eruptions may ephemerally increase the nitrogen flux to the atmosphere, but are insignificant compared to the 4 × 1021 g of nitrogen stored in the atmosphere.
AB - Volatile releases through volcanic eruptions are one of the major processes contributing to the global nitrogen cycle. Past studies have often estimated the magnitude of this flux using volcanic emission measurements, which are limited to currently active systems and sensitive to atmospheric contamination. Another possible approach is the measurement of nitrogen in melt inclusions, which are parcels of magmatic melt trapped prior to eruption. This methodology requires appropriate analytical parameters for nitrogen analysis in silicate glasses by secondary ion mass spectrometry (SIMS), which have not yet been established. To this end, calibrations for nitrogen were obtained using ion implanted basaltic and rhyolitic glasses. We demonstrate that water content significantly affects the ion yields of 14N + and 14N16O −, as well as the background intensity of 14N + and 12C +. Application of implant-derived calibrations to natural samples provide the first reported concentrations of nitrogen in melt inclusions. These measurements were made on samples from the Bishop Tuff in California, the Huckleberry Ridge Tuff of the Yellowstone Volcanic Center, and material from the Okaia and Oruanui eruptions in the Taupo Volcanic Center. In studied material, we often find maximum nitrogen contents of less than 45 ppm and that nitrogen concentration varies positively with CO2 concentration, which reflects a partial degassing trend. Using the maximum measured nitrogen contents for each eruption, we find that the Bishop released >3.4 × 1013, the Huckleberry Ridge released >1.4 × 1014, the Okaia released >1.0 × 1011, and the Oruanui released >4.5 × 1013 g of nitrogen. Simple calculations suggest that with concentrations such as these, rhyolitic eruptions may ephemerally increase the nitrogen flux to the atmosphere, but are insignificant compared to the 4 × 1021 g of nitrogen stored in the atmosphere.
KW - Explosive volcanism
KW - Melt inclusions
KW - Nitrogen cycling
KW - Secondary ion mass spectrometry
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U2 - 10.1016/j.chemgeo.2016.10.019
DO - 10.1016/j.chemgeo.2016.10.019
M3 - Article
AN - SCOPUS:84999810282
SN - 0009-2541
VL - 447
SP - 27
EP - 39
JO - Chemical Geology
JF - Chemical Geology
ER -