12
peer 7-8 еv, k- the Boltzmann constant, to this energy situation corresponds
temperature Т of the order 60000 С
o
, at which there was the complete
dissociation of chemical combinations on elements and ions. Therefore, the
Earth should have inherited the solar spectrum of elements with potentials
of ionization up to 8 еv. It follows, that the relative abundances
of metals on
Earth must correspond t
o
their relative abundances in the Sun.
14
Table 2
The chemical composition
of the primordial Earth
(with reference to the process of magnetic differentiation)
( Larin, 1980 )
Element
Solar
abundance
(normalized
to silicon )
Coefficient
deficiency
(primordial)
Abundance on the Earth
normalized
to silicon
atomic,%
weight,%
Silicon
100
1
100
19.5
45
Маgnesium
79
1
79
15.5
31
Iron
13
1
13
2.5
12
Calcium
4.5
1
4.5
0.9
3
Аluminium 5.0
1
5.0
1.0
2
Sodium
3.6
1
3.6
0.7
1.5
Oxygen
3,000
10
-3
3.0
0.6
1.0
Carbon
1,600
10
-3
– 10
-4
0.16 – 1.6 0.03 –0.3
0.03 – 0.3
Sulphur
60
10
-2
– 10
-3
0.06 – 0.6 0.01 –0.1
0.03 – 0.3
Nitrogen
300
10
-4
– 10
-5
0.003 – 0.03 less 0.01
less 0.01
Hydrogen
3, 000, 000
10
-3
– 10
-4
300
59
4,5
Notes: 1.Solar abundances are taken from L.Aller (1963);
2.The frequent association of Fe is taken into account
of abundance
Mn, Cr, Co.
Cosmochemical regularities are an evidence for the plasma state of proto-
matter in the nebular stage of solar system formation. The pinch effect,
acting on the plasma at a certain point, precisely allowed generation of
globules in the protoplanetary disk. The research carried out by T.N.Eneev
and N.N.Kozlov (1977) shows that gravitational evolution of such a model
can only produce a planetary system with all the known characteristics
(planet numbers, orbits and rotational characteristics), if planetary accretion
precedes condensation.
In this scenario, immediately after accretion, extended gaseous globules
should represent the Earth-type planets. With diminished levels of radiation
(due to the decay of short-lived isotopes) and decrease of the Coulomb
barrier, the processes of condensation, agglomeration and collapse
commenced. The time required for collapse of the proto-nebula was the time
between the loss of gravitational stability and the formation of the
protoplanetary disk
is estimated as 10
6
years (Kuroda, 1961; Reeves, 1976 ).
Short-lived isotopes produced in this process are most likely to be
10
Be,
26
Al,
53
Mn,
60
Fe, and others with half-lives that approximate 10
6
years.