Table 1 Fe isotope fractionation dataa

From: Extremely cold ocean temperatures in iron formation brine pools of snowball Earth

 

T (° C)

T (K)

1000lnβ [Fe(H2O)63+)]b

1000lnβ [Fe(H2O)62+)]b

1000lnα (Fe3+ -Fe2+)c

1σd

Reference

Theoretical data (Density functional theory estimation)

–0.15

273

9.488

6.013

3.475

 

59

24.85

298

8.070

5.095

2.975

 

59

49.85

323

6.943

4.370

2.573

 

59

99.85

373

5.291

3.314

1.977

 

59

199.85

473

3.354

2.088

1.266

 

59

299.85

573

2.310

1.433

0.877

 

59

Experimental data

0

273.15

  

3.57

0.38

60

22

295.15

  

3.00

0.23

60

  1. aData show the isotope fractionation values between Fe(III) and Fe(II) calculated using first-principles Density functional theory (DFT) method59, as well as the experimental results between Fe(III) and Fe(II)60.
  2. bLogarithm of the reduced partition function, lnβ (‰), for the pair 56Fe-54Fe of aqueous Fe(III) or Fe(II).
  3. cIsotope fractionation value, as 1000lnα (‰), between the aqueous Fe(III) and Fe(II), is: 1000lnβFe(III) - 1000lnβFe(II) at a given temperature T. Under different temperature conditions, the relationship between isotope fractionation values and temperature can be expressed as: 1000lnα = A*106/T2 + B, where T is in Kelvin. For the modeled data from Fujii et al.59, A = 0.2508 and B = 0.1435 (Fig. 3b).
  4. dError of isotope fractionation values (1000lnα) obtained by experiments.
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