Dissolution of K in molten iron at high pressure and temperature

Abstract

Partitioning of K between molten iron and silicate melt was examined at about 26 GPa and 2600°C using a mixture of pure iron and natural microcline as the starting material. The dissolution of K in molten iron up to about 0.2 wt % was confirmed. The distribution coefficient of K between molten iron and silicate melt was about 3.8×10−2 (atomic ratio). This value suggests the presence of 5 ppm K in the earth's core, yielding 3×1010 W for the present day heat generation by K.

The abundance of potassium in the Earth’s core

“…The chemical composition of adularia analyzed by an electron probe microanalyzer (EPMA/WDS: JEOL JXA-8800 M) is shown in Table 1. K-feldspar was also used in the previous studies (Ito et al, 1993;Chabot and Drake, 1999;Hirao et al, 2006) and the reason using K-feldspar in our study includes the purpose for comparing with these previous studies. The chemical composition of this mineral is far from the compositions of the early and current mantles.…”

“…e l s e v i e r . c o m / l o c a t e / p e p i and high temperature (e.g., Ito et al, 1993;Ohtani and Yurimoto, 1996;Chabot and Drake, 1999;Gessmann and Wood, 2002;Murthy et al, 2003;Hirao et al, 2006;Bouhifd et al, 2007;Corgne et al, 2007). These studies reported that the partition coefficient of potassium, D K (=the content of potassium in metal [wt%]/ the content of potassium in silicate [wt%]), could vary from 0.0047 to 2.4, depending on the effects of temperature, pressure, oxygen fugacity, and metal and silicate compositions (e.g., NBO/T; the number of non-bridging oxygen divided by the number of tetrahedral cations).…”

Metal–silicate partitioning and constraints on core composition and oxygen fugacity during Earth accretion

“…Note that there is no significant pressure effect on the metal-silicate partitioning of Si, Ti, Zn and Cu (see values of c coefficient and corresponding standard deviations in Table 7). References are: C99, Capobianco et al (1993); JD00, Jaeger and Drake (2000); H07, Holzheid et al (2007); JW97, Jana and Walker (1997); WW05, Wade and Wood (2005); KW97, Kilburn and Wood (1997); WW01, Wade and Wood (2001); M07, Malavergne et al (2007); M06, Mann et al (2006); TW95, Thibault and Walter (1995); GR08, Gessmann and Rubie (1998); CA03, Chabot and Agee (2003); H94-96, Hillgren et al (1994Hillgren et al ( , 1996; LA96-01, Agee (1996, 2001); O97, Ohtani et al (1997); I93-95-98, Ito et al (1993Ito et al ( , 1995Ito et al ( , 1998; BJ03, Bouhifd and Jephcoat (2003).…”

Crystal structure of anhydrous phase X, K1.93(Mg2.02Cr0.02)Si2.00O7

“…Specifically, the radioactive potassium isotope 40 K is a major source of radiogenic heat throughout the lithosphere, from the crust to the core (e.g., Ito et al, 1993, Murthy et al, 2003. Navon et al (1988) found fluid inclusions in diamonds from Zaire and Botswana that contained 12 -30 wt% K 2 O.…”