Supplemental Table S6. Major element compositions. sample ID sample name SiO2 Al2O3 FeO MnO MgO CaO Na2O K2O TiO2 P2O5 Total Method Source 1 1465-7-1 47.92 20.74 8.25 0.15 5.44 13.68 2.66 0.17 0.89 0.28 100.17 EPMA This_study_fused_glass 2 1466-9-1 49.18 18.19 7.82 0.14 2.83 6.43 5.82 3.60 2.83 0.94 97.78 EPMA J_Natland_unpublished 3 1467-2-1 49.28 15.44 10.46 0.21 6.71 12.19 3.08 0.14 1.46 0.28 99.27 EPMA This_study_fused_glass 4 1468-5-1 50.14 15.67 9.93 0.18 5.04 9.83 3.81 1.32 3.06 0.48 99.46 EPMA J_Natland_unpublished 5 1471-1-2 50.08 15.96 9.22 0.16 5.61 9.13 3.48 1.31 3.05 0.66 98.66 EPMA J_Natland_unpublished 6 1474-6-1 50.31 16.88 8.57 0.17 8.68 12.45 2.73 0.01 1.11 0.08 100.98 EPMA J_Natland_unpublished 7 1475-7-1 49.75 16.22 10.80 0.14 5.32 6.65 4.28 2.08 2.51 0.95 98.71 EPMA This_study_fused_glass 8 BONZ-1-1 51.03 14.65 10.18 0.18 7.25 12.27 2.63 0.13 1.44 0.13 99.90 EPMA J_Natland_unpublished 9 BONZ-5-1 49.55 16.29 9.06 0.17 8.14 12.51 2.65 0.03 1.19 0.08 99.67 EPMA J_Natland_unpublished 10 CRAT-9-1 48.32 19.52 9.82 0.13 2.80 8.96 4.35 1.36 2.99 0.86 99.10 EPMA This_study_fused_glass 11 D21-3 47.20 15.00 12.00 0.17 5.39 7.76 2.63 1.07 2.63 0.65 99.00 XRF Davis_et_al_1995 12 JS-1-8 53.10 19.17 9.49 0.18 1.00 5.94 5.47 2.50 1.93 1.01 99.79 EPMA This_study_fused_glass 13 JS-2-3 55.61 17.09 7.84 0.16 2.50 5.17 5.18 3.04 2.00 0.92 99.51 XRF Gee_et_al_1991_published 14 JS-2-5 47.67 17.26 9.31 0.17 4.75 10.16 4.18 1.97 2.78 0.70 98.97 XRF Gee_et_al_1991_unpublished 15 JS-4-7 56.24 15.00 12.63 0.25 1.63 5.34 4.53 2.27 1.63 0.75 100.28 XRF Gee_et_al_1991_unpublished 16 JS-5-19 49.85 16.22 11.55 0.16 6.78 10.15 2.89 0.44 1.42 0.19 99.74 XRF Gee_et_al_1991_unpublished 17 JS-12-4 53.02 17.25 8.69 0.19 2.54 5.65 5.52 3.67 2.28 1.13 99.95 XRF Gee_et_al_1991_unpublished Notes: Data in weight percent; XRF techniques: Gee et al. [1991] and Davis et al. [1995]. Electron Microprobe techniques: accuracy was evaluated by comparative analyses on Smithsonian standard basaltic glass VG-2. Fused Glasses: analyzed using a Cameca SX-100 electron microprobe at 15 keV accelerating potential, 10 nA beam current, and a 20 mm spot size, using standard ZAF corrections [Schiffman and Roeske, 2002]. Glasses analyzed by J. Natland used SIO techniques, such as in Dieu [1995]."