Table 1. Summary table comparing important attributes of each statistically distinct pumice population.
The table compares the petrography, major and trace element glass composition, rhyolite-MELTS pressure, MI H2O content, MI H2O-CO2 saturation pressure, zircon saturation temperature, and maximum quartz residence time [using the diffusion coefficient of Cherniak et al. (18)]. Eruption ages (± 2σ) are from this study (14C of underlying soil), except for (a) Nagaoka et al. (27) (approximate age from stratigraphy) and (b) Smith et al. (25) (14C of correlated lacustrine ash). Volume % crystallinity (c) is from Geshi et al. (23).
| Iwato | Otsuka | Fukaminato (Lwr) | Fukaminato (Mid #1) | Fukaminato (Mid #2) | Arasaki-1 | Arasaki-2 | Arasaki-3 | Kenashino (Lwr) | Kenashino (Upr) | Osumi (XR) | Osumi (XP) | Osumi (Gray) | Ito (XR) | Ito (Mod. xtal) | Ito (Gray) | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Type | Pfl | Pfa | Pfa | Pfa | Pfa | Pfl | Pfl | Pfl | Pfa | Pfa | Pfa | Pfa | Pfa | Ignimbrite | Ignimbrite | Ignimbrite |
| Age (ka) | ∼60 ka (a) | 33.450 ± 0.346 | 32.249 ± 0.506 | 32.249 ± 0.506 | 32.249 ± 0.506 | 32.249 ± 0.506 | 32.249 ± 0.506 | 32.249 ± 0.506 | 31.11 ± 0.189 | 31.11 ± 0.189 | 30.009 ± 0.189 (b) | 30.009 ± 0.189 (b) | 30.009 ± 0.189 (b) | 30.009 ± 0.189 (b) | 30.009 ± 0.189 (b) | 30.009 ± 0.189 (b) |
| Pumice samples | IW-01-01 to 14 | F-A1-02, 03, 04, 05, 06, 07, 08 | F-A1-01; F-A2-02, 03, 04, 06 | F-A2-01, 05, 08 | A-01, 02, 06-08, 12 | A-03, 04 | A-10, 13, 15 | K-A-01, 02, 03, 05; K-B-05 | K-A-04; K-B-01 to 04; K-B-06 to K-B-11 | OS-B1-01,04, 05, 07, 10-13, 15; OS-B2-07;OS-B3-02, 04, 05, 09 | OS-B2-03, 01, 02, 05, 06, 08-10, 12-15; OS-B1-02, 06, 08, 14 | OS-B3-01, 06, 07, 13 | ITO-D1-01 | ITO-D1-02, 03-07, 09-15, ITO-D2-02, 03-08 | ITO-D1-08, ITO-D2-01 | |
| Pumice selected | IW-01-04 | OC4-02, 03, 06 | F-A1-02 | F-A2-02 | F-A2-01 | A-08 | A-03 | A-10 | K-B-01 | OS-B1-01 | OS-B2-03 | OS-B3-01 | ITO-D1-01 | ITO-D1-02 | ITO-D2-01 | |
| Crystallinity (wt %) | 37% | 20–26% | 4% | 32% | 31% | 11% | 33% | 21% | 11% | 12% | 2% | ∼20–25% | 18% | 15% | 11% | |
| Crystallinity (vol %) (c) | 22–29% | 20% | 18–20% | 18–20% | 18–20% | 18–20% | 18–20% | 18–20% | 18–20% | 12–15% | 12–23% | 12–23% | 12–23% | 12–23% | 12–23% | |
| Petrography | Pl ≈ Qtz >> Opx (<1%) > rare oxides; Qtz is MI-rich | Pl > Qtz >> Opx > rare Cpx | Qtz > Pl >> oxides > rare Opx > rare Bt; Volcanic lithic fragments w/in pumice | Pl > Qtz >> Opx (1-2%) > rare oxides > rare Cpx | Pl >> Qtz >> Opx (∼3%), rare oxides; Pl often has blueish core | Pl > Qtz >> Opx; Dense glass. Poorly vesicular | Pl > Qtz >> Opx; Moderately vesicular | Pl > Qtz >> Opx; very Large quartz (some >2 mm); Highly vesicular | Pl >> Qtz > Opx (<1%) and Cpx (?), very rare small oxides; Abundant lithic inclusions | Pl > Qtz > Opx > oxides | Pl >> rare small Qtz > rare Opx > rare oxides; ∼Aphyric, elongated vesicles | Xtal-rich (<0.5 mm), Plag and Opx, No Qtz; Gray pumice, often mingled with white pumice glass | Large Pl > Qtz >> Opx > rare Hbl (?) | Pl >> small Qtz > rare Opx | Pl ≈ Qtz > Opx > Hbl (?); Gray pumice | |
| Composition | High: Al2O3, Sc | Mod. high Sr, Zr, REE | High: Al2O3, Na2O, K2O | High: FeO, CaO, Na2O, Sr, Zr | High: SiO2, FeO, CaO, Sr | Similar to Fukaminato (lower) | High: Sc, most trace elements | High: SiO2, FeO, CaO, Sr, Y, La, Zr, Nd, Th | Similar to Fukaminato (mid #2) | High: FeO | High: Na2O, Li, Ba, Nd | High: CaO, FeO, Sr | High: SiO2, CaO | High: Li, Sr, Ba, Eu | High: SiO2 | |
| Low: FeO, Sr, Y, Zr, Nb, Nb, Th | Low: FeO, CaO, Sc, Sr, Zr | Low: K2O | Low: Al2O3, K2O, Sc | Low: Ba, Y, Sr, Nb, La | Low: Ca,Sr | Low: Al2O3 | Low: K2O, Sc, Nb | Low: V, Zr | Low: SiO2, Ba, Sc, Y, Nb, REE | Low: K2O, Sc, Ga, Ba, Nb, Pb | Low: FeO, Zn, Pb | |||||
| MELTS P (avg) | 104 MPa | 93 MPa | 114 MPa | 110 MPa | 89 MPa | 101 MPa | 108 MPa | 89 MPa | 90 MPa | 86 MPa | 112 MPa | 131 MPa | Max = 222 MPa | 89 MPa | 120 MPa | 93 MPa |
| MI H2O | 4.1–4.7 wt % | 4.5–7.2 wt % | 3.5–6.1 wt % | 3.8–6.3 wt % | 3.5–5.5 wt % | 5.8 wt % | ||||||||||
| MI equil. pressure | 105–135 MPa | 135–175 MPa | 104–215 MPa | 100–215 MPa | 80–180 MPa | 249 MPa | ||||||||||
| Mean pumice Zr | 85 ppm | 106 ppm | 69 ppm | 99 ppm | 99 ppm | 88 ppm | 77 ppm | 103 ppm | 120 ppm | 94 ppm | 110 ppm | 91 ppm | 117 ppm | 97 ppm | 113 ppm | 112 ppm |
| Mean zircon sat. temp. | 742°C | 759°C | 728°C | 752°C | 753°C | 743°C | 733°C | 756°C | 769°C | 749°C | 761°C | 745°C | 769°C | 752°C | 764°C | 764°C |
| Max. qtz residence | 1600 years | 310 years | 590 years | 420 years | 1480 years | 770 years | 770 years | 1180 years | 740 years | 620 years | 60 years | No quartz | 700 years | 860 years | 780 years |