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exchange than that in the white soft spots and testifies to the hydrogenous nature of
the nodules.
Table. 1. СaCO 3 content in CAs, thermal characteristic, data on isotopic
composition and X-ray diffraction pattern for calcite
Soil,
horizon,
depth, cm
Soil I,
В2са,170
-200
Soil II,
В1са,130
-170
Soil III,
В1са,130
-150
Soil IV,
В2са,
150-170
Sample
White
soft spots
White
soft spots
with hard
core
White
soft spots
with hard
core
Hard
nodules
Content
CaCO 3 in
CAs, %
isotopic
composi-
tion of
carbon
in CAs,
‰
100 -9,6
Data on
thermal analysis
temperature (°С) of
X-ray
diffraction
pattern
maximum
beginning
end d 104
of structural decomposition
700
810
740
860
800
890
0.037
69 -10,7 790 880 920 0.037
89 -12,0 770 880 920 0.037
89 -13,2 800 870 920 0.037
We can conclude that the white soft spots and hard nodules in the Chernozems
of the steppe area of the Southern Pre-Ural develop in distinctly different
conditions, i.e., automorphic and hydromorphic ones, accordingly. If the white
spots in the soil of the upper part in catena form from the true solution It can
marked out the intermediate forms of CAs – the white soft spots with hard cores
that develop in the transit part of catena under interchange of automorphic and
hydromorphic conditions of soil formation. The complex study of CAs using
hierarchical morphological approach and instrumental techniques lets us to get
additional information and data that point directly to the genesis of the different
kinds of CAs.
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