TWO EPISODES OF LUNAR BASALTIC VOLCANISM IN MARE FECUNDITATIS AS REVEALED BY LUNA-16 SOIL SAMPLES
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Supplementary Tables S1–S3
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Raman spectra of the mineral phases of the Luna-16 main group basalts were obtained using a JY Horiba XploRA Jobin confocal Raman spectrometer attached to an Olympus BX41 polarizing microscope equipped with two lasers (532 and 785 nm). The operating temperature of the CCD (IVAC Andor CCD) detector is –51 °C, cooled by Peltier elements. Spectra accumulation was performed at excitation by the 532 nm laser at a power of 25mW, 100× magnification (spatial resolution of <1 μm), a spectrometer slit of 100 μm, and a confocal hole of 300 μm. Spectra were acquired in the range 50 to 1200 cm–1 using a 2400T spectral grating. The accumulation time of each spectral window was 120 s (3 x 40 s). Initial processing of the spectra was carried out using LabSpec, ver. 5.78.24. Data are provided in supplementary data table S1. EMPA analyses used 15 kV accelerating voltage, 30 nA focused beam, 20 s on-peak counting time and 10 s for each background. A PAP correction was applied for quantification. Data are provided in supplementary data table S2. The SIMS data processing and filtering procedure applied to the data acquired for this study are similar to those discussed by (Snape, J.F., Curran, N.M., Whitehouse, M.J., Nemchin, A.A., Joy, K.H., Hopkinson, T., Anand, M., Bellucci, J.J., Kenny, G.G., Ancient volcanism on the Moon: Insights from Pb isotopes in the MIL 13317 and Kalahari 009 lunar meteorites. Earth Planet. Sci. Lett. 2018, 502, 84–95; Merle, R.E., Nemchin, A.A., Whitehouse, M.J., Snape, J.F., Kenny, G.G., Bellucci, J.J., Connelly, J.N., Bizzarro, M., 2020. Pb-Pb ages and initial Pb isotopic composition of lunar meteorites: NWA 773 clan, NWA 4734, and Dhofar 287. Meteorit. Planet. Sci. 55, 8, 1808-1832.) The data are presented in Supplementary table S3.