Table 1 Estimated global H2O flux by subducting talc based on the observed super-hydration processes in the cold subduction zones
From: Formation of the 15 Å phase as the most expanded hydrated mineral in cold subduction zone
Parameters | Value | References |
|---|---|---|
thickness of oceanic crust sediment (layer 1) basalt (layer 2 A, B) gabbro with layered peridotite (layer 3) | 5–8 km 0.4–0.9 km 1.5–2.1 km 4.5–5.0 km | Geissler et al. and White et al.78,79 Straume et al. and references therein80 |
volume of oceanic crust sediment (layer 1) basalt (layer 2 A, B) gabbro with layered peridotite (layer 3) | 113–337 × 106 km3 2100 × 106 km3 | Straume et al. and references therein80 Wyllie82 |
volume of talc in the subducting slab in layer 1 ( ~ 5–20 vol.%) in layer 2 ( < 5 vol. %) in layer 3 ( ~ 5–20 vol. %) | ~5.65–67.4 × 106 km3 < ~30 × 106 km3 ~ 75–300 × 106 km3 | Schmidt & Poli1 *volumetric ratio of layer 2: layer 3 = 2:5 |
mass of talc in the subducting slab in layer 1 in layer 2 in layer 3 | ~1.6–19 × 1022 g < ~8.3 × 1022 g ~21–83 × 1022 g | *density of talc: ~2.78 g/cm3 (Gleason et al.,)35 |
amount of H2O by subducting talc and its hydration products in cold subduction zones subducting talc 15 Å phase 10 Å phase | ~0.42–1.5 × 1022 g (av. ~0.96 × 1022 g) ~0.36–1.3 × 1023 g (av. ~8.3 × 1022 g) ~1.2–4.5 × 1022 g (av. ~2.9 × 1022 g) | Estimated from this study: talc, Mg3Si4O10(OH)2 15 Å phase, Mg3Si4O10(OH)2∙nH2O (n = 8) 10 Å phase, Mg3Si4O10(OH)2∙ nH2O (n = 2) |
H2O flux by subducting talc and its hydration products in cold subduction zones subducting talc 15 Å phase 10 Å phase | ~0.21–0.75 × 1014 g/yr (av. ~0.48 × 1014 g/yr) ~1.8–6.5 × 1014 g/yr (av. ~4.2 × 1014 g/yr) ~0.62–2.2 × 1014 g/yr (av. ~1.4 × 1014 g/yr) | Estimated from this study: *assuming the cycle of oceanic crust to be 200 Ma *assuming the cold subduction zones in global subduction system to be ~28.5% |
