Table 1 Resulting compositions with dual processes of collisional erosion and fractional re-condensation.

From: Cosmochemical fractionation by collisional erosion during the Earth’s accretion

 

Bulk Earth

Assumed core composition 44

EH-like planet

EH-like planet with adjusted core size

   

0% eroded mantle

25% eroded mantle

40% eroded mantle

0% eroded mantle

25% eroded mantle

40% eroded mantle

Mg

15.6

 

13.8

12.8

10.8

15.9

15.8

15.6

Al

1.6

 

1.0

1.1

1.1

1.2

1.4

1.6

Si

16.6

7

15.0

13.7

11.5

17.2

16.9

16.6

Ca

1.7

 

1.1

1.2

1.2

1.3

1.5

1.7

Na

0.2

 

0.2

0.2

0.1

0.2

0.2

0.2

K

0.0

 

0.0

0.0

0.0

0.0

0.0

0.0

O

30.5

4

27.9

25.8

21.9

30.5

30.5

30.5

Fe

31.4

82

38.0

41.9

49.6

31.4

31.4

31.4

Co

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0.1

Ni

1.6

5

2.3

2.5

3.0

1.6

1.6

1.6

S

0.6

2

0.6

0.6

0.7

0.6

0.6

0.6

  1. We compare the actual bulk Earth composition (first column) (calculated based on bulk silicate Earth12 composition and cosmochemical estimates of core composition44 (second column)) with the EH-like Earth (third column) after erosion of (i) 15% of a crust composed of pseudo-eutectic melts produced at 0–5 GPa and (ii) 0–40% of its mantle. The erosion yields a significant depletion in the lithophile elements (Mg, Si, O, Na, Al and Ca) compared with the siderophile elements (Fe, Ni, Co and S). By adjusting the core size to the actual terrestrial core size (by fixing the concentrations of the siderophile elements to that of the Bulk Earth), the composition of our EH-like planetary model can reach values very close to that observed in the present-day Earth.
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