C - Lublin

.
m
131.5
131.0
I
Height above sea level
130.5
130.0
129.5
129.0
128.5
128.0
II
III
. .
.
.
.
IV
. .
.
-White soft spot
-White soft spot with hard core
-Whity-gray hard nodule
Stream-bed
127.5
0 50 100 150 200 250 300
m
Fig. 1. The scheme of catena.
Extension of catena
The differences that have been revealed in the microstructure of CAs in the
soils of catena are well preserved on the submicrolevel of observation. The white
soft spots is made of well crystal calcite, the hard nodules are characterized by
collomorphic undifferentiated texture. In the soils of transit part in catena there is a
cellular texture, the calcite grains are well crystallized mainly, the “boundary” of
cell is made of cryptocrystalline calcite.
Based on the X-ray diffraction pattern and thermal analysis all the CAs are
composed of pure calcite. The calcite content in CAs varies from 70 to 90% and
has no differences throughout the catena (Table 1). The distribution of isotopic
composition of carbon in calcite of the CAs have a catena regularity. The isotopic
composition of carbon in the white soft spots and hard nodules is clear different
and amounts respectively -9,6‰ and -13,2‰. The intermediate forms of CAs (the
white soft spots with hard cores) have an intermediate isotopic composition of
carbon as well – -10,7‰ , -12,0‰. At the same time, the isotopic composition of
humus carbon in the upper humuc A1 horizon does not differentiate throughout the
catena and amounts -23,4– -24,7‰ in all the soils studied. It means that calcite in
the hard carbonate nodules formed in more hindered conditions of gaseous
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