Microprobe analysis SWIR basaltic glasses

The file EDUL_EMPA-EH.csv includes a geochemical dataset of basaltic glasses from the Southwest Indian Ridge (cruise EDUL MD-107). The major element compositions were measured by E. Humler between 1998 and 1999 at the University of Paris 7 using the CAMECA SX50 electron microprobe of the CAMPARIS[1] analytical platform. Analytical conditions included a 15 kV accelerating voltage, 20 nA beam current, and a 10 μm beam diameter. Counting times were 30 s for Na₂O, TiO₂, and FeOt (where “t” indicates total iron), 60 s for Al₂O₃, SiO₂, CaO, and MgO, 70 s for K₂O, and 100 s for P₂O₅ and MnO. The analytical sequence utilized simultaneously the four spectrometers equipped with TAP, LIF, and PET crystals, in the order listed bellow: Analytical Sequence: TAP: Na₂O, CaO, MnO TAP: TiO₂, MgO, P₂O₅ LIF: FeO, K₂O PET: SiO₂, Al₂O₃ For each sample, a minimum of six analytical spots was performed and averaged to obtain representative compositions go the melts. Every 30 to 50 measurements, five points were analyzed on the Lamont in-house natural glass standard JDF-D2 (East Pacific Rise) provided by C.H. Langmuir. Regular analysis of the JDF-D2 throughout each analytical session allowed for monitoring and correcting instrumental drift of the electron microprobe, following the method described by Reynolds and Langmuir (1997). All analyzed compositions were normalized to the recommended composition of the JDF-D2 standard (Reynolds and Langmuir, 1997): JDF-D2 Recommended Value ±1σ Precision [2] (wt.%) SiO₂: 50.80±0.17 TiO₂: 1.92±0.02 MnO: 0.22±0.02 Al₂O₃: 13.71±0.05 FeOt: 12.12±0.13 MgO: 6.59±0.09 CaO: 10.64±0.09 Na₂O: 2.75±0.05 K₂O: 0.20±0.005 P₂O₅: 0.22±0.01 Total: 99.77 [1] http://ecceterra.sorbonne-universite.fr/fr/les_services_aoc/les_plateformes_analytiques2/plateforme_men.html [2] typical values on 5-6 replicate analyses Bibliography : Reynolds J. R., Langmuir C. H. (1997) Petrological systematics of Mid-Atlantic Ridge south of Kane: implications for ocean crust formation. J. Geophys. Res. 102, 14915–14946.