Fig. 5: Results of Mg budget calculations. The calculations are done by Eqs. (3) and (4).
From: New isotope constraints on the Mg oceanic budget point to cryptic modern dolomite formation
The solid black line shows the calculated Mg flux into the dolomite sink, Fdol, and the low-temperature hydrothermal (LTH) sink, FLTH, given the isotope fractionation by the LTH system, εLTH-sw, is 1.6‰ and the Mg flux into the high-temperature hydrothermal (HTH) sink, FHTH, is in the range of 0.24–1.4 Tmol yr−1. The orange lines show the results for different εLTH-sw values in the range of 0.6–7‰ (shown: 0.6, 1, 1.6, 2, 3, 5, 7‰). The black-dotted lines define the possible range of Fdol and FLTH given the allowed range in FHTH. Two extreme scenarios are presented, equivalent to: (a) a rapid increase in [Mg]sw (1.2 mmol kg−1 in Myr) with no change in seawater δ26Mg. This scenario results in minimum output fluxes; and (b) a slow rise in [Mg]sw (0.5 mmol kg−1 in Myr) and larger changes in seawater δ26Mg (0.025 ‰ Myr−1). This scenario results in maximum output fluxes.
