Program > Browse abstracts by speaker > Sverjensky Dimitri

Experimental studies of rock solubilities and the compositions of fluid inclusions in diamonds have established that planetary fluids contain all the rock-forming elements and trace elements. The wide range of fluid compositions, including the development of immiscibility, constitute a formidable challenge for theoretical models of the reactivity of fluid-rock-melt systems. The DEW24 model calibrated with experimental solubilities of mafic and ultramafic rocks in water [1] now includes a very wide range of H2O/CO2 ratios, immiscibility of H2O-H2 fluids and H2O-fluid hydrocarbons, and calibrated sulfate complexes. DEW24 provides equilibrium constants for aqueous speciation/solubility and chemical mass transfer models. Three predictive applications follow: in reducing environments in subduction zones, immiscible H2 reacts irreversibly with carbonated [2]; in oxidizing environments in subduction zones, Na-sulfate complexes are so strong they stabilize pyrite at QFM+2 resulting in high concentrations of isotopically heavy sulfate for the mantle wedge [3]; and, deeper in the upper mantle, at 1,000°C and 5.0 GPa, irreversible mass transfer during metasomatic reactions between aqueous fluids and upper mantle rocks with diamond formation indicate that the mineral inclusions in diamonds reflect the fluids involved and the extent of fluid-rock reaction, rather than the particular geologic rock environment [4].

[1] Huang F. & Sverjensky D. A. (2019) Extended Deep Earth water model for predicting major element mantle metasomatism, Geochim. Cosmochim. Acta, 254, 192.

[2] J. Huang et al. (2024) Reaction path model of the formation of abiotic immiscible hydrocarbon fluids in subducted carbonated serpentinites, Lanzo Massif (Western Italian Alps), Lithos, 468-469, 107498.

[3] Beaudry P. & Sverjensky D. A. (2024) Oxidized sulfur species in slab fluids as a source of enriched sulfur isotope signatures in arcs, G3, 25 (7), e2024GC011542.

[4] Rinaldi M. et al. (2023) Importance of carbon to the formation and composition of silicates during mantle metasomatism, Geochim. Cosmochim. Acta, 356, 105.