Table S5. Estimated high-temperature hydrothermal Mo and Cr fluxes. Mo Cr F(ht)a ∆[Me]b Fhyd / Friv ∆[Me]c kg y-1 nM % nM 2.62 x 1013 100 0.85 3.88 a Assuming: Q(ht) = 3.2 x 1012 W (1); ∆T(ht) = 350ºC (1, 2); cp = 5.8 J g-1 K-1 (1) b [Mo]SW from (3); [Mo]fluid from (4) c [Cr]SW from (5); [Cr]fluid from (6) Fhyd / Friv % 0.02 1. Elderfield H, Schultz A (1996) Mid-ocean ridge hydrothermal fluxes and the chemical composition of the ocean. Ann Rev Earth Planet Sci 24:191-224. 2. Stein CA, Stein S, Pelayo AM (1995) Heat flow and hydrothermal circulation. AGU Geophys Monogr 91:425-445. 3. Collier RW (1985) Molybdenum in the Northeast Pacific Ocean. Limnol Oceanogr 30:1351-1354. 4. Kishida K, Sohrin Y, Okamura K, Ishibashi J (2004) Tungsten enriched in submarine hydrothermal fluids. Earth Planet Sci Lett 222:819-827. 5. Jeandel C, Minster JF (1987) Chromium behavior in the ocean: Global versus regional processes. Global Biogeochem Cyc 1:131-154. 6. German CR, Campbell AC, Edmond JM (1991) Hydrothermal scavenging at the Mid-Atlantic Ridge: Modification of trace element dissolved fluxes. Earth Planet Sci Lett 107:101-114.