|Abstract: ||The paper presents the findings of the changeability
of the qualitative parameters of coal beds and the
strength parameters of neighbouring rocks in the faulting
zones of the Upper Silesian Coal Basin (the USCB)
as well as relations between the geometrical parameters
of faults and the intensity of their changes. The research
area included the region of the main saddle and
its axis constitutes the Kłodnica fault and the 405 coal
seam of Załęże beds. The investigation of the qualitative
parameters of coal at the interval of 1—10 m from
the fault surface was done on 205 groove samples taken
from 10 mines. The analysis of the coal included its basic
composition, technological properties and coking,
petrographic and physical qualities as well as its structure
in infrared radiation (IR). The results obtained underwent
statistical analysis and were presented in the
form of tables and figures.
The findings showed that the faulting zones in the
USCB are places where there are significant reductions
in strength parameters of rock mass; that is why their
patency for the migration of gases and water can be intensified
and as a consequence this causes a danger of
fall. Under favourable conditions, depending on the nature
of discontinuity, degrading and aggrading changes
of coal quality are generated in these zones. The opening
of fault fissures for fluid flow resulted in degradation
of the coal quality, whereas in the case of their
closeness, the cumulated friction heat might cause the
growth of coalification simultaneously increasing the
coal quality (30% and 12% of the fault population respectively).
Hypergenic changes resulted in coal of the
qualitative parameters close to the one derived from the
zones of eluvium cover and so-called red beds. In the
faulting zones of an aggrading nature, both the interval
and the scale of changes in the coal parameter values
were definitely smaller but only directly on the fault
surface, whereas their reverse direction caused an increase
in the degree of coalification (friction metamorphism).
The results of the research examining the coal
by means of the spectroscopy method in the IR proved
the degrading and aggrading nature of coal changes in
the faulting zones although the relations observed were
In the tectonic breccia filling in some fault fissures,
the fact that coal weathered and changed to a varying
extent at high temperatures was proved. The way this
happened as well as the unchanged nature of the coal
parameters of the beds surrounding the breccia prove
their allochtonic origin. This is connected with bed
fires and transport as well as faulting breccia.
In the majority of the faulting zones examined
(58%), a significant diversification of coal parameter
values was not observed. The changeability of their values
usually did not exceed 5%, was random in nature,
and did not show correlations with the distance from
the fault. What also decreased in the faulting zones was
the resistance to one-axis rock compression surrounding
the coal beds (about 54% to 67%), including the interval
up to 11 m from the fault surface.
The nature and intensity of coal change points to the
important relations with some geometrical fault parameters.
Hypergenic coal changes were observed, among
other things, in the fault fissures of the dominant
NW-SE and NE-SW run direction, with a predominant
throw in the direction to the SW. In line with the fall of
the intensity of weathered changes, the run of faults
evolved into the WNE-ESE direction. The faults of
such expansion in the USCB are characterized as fragile.
Because they were formed in the period of the inversion
of the Upper Silesian basin in a tense regime of
compressions, they show a substantial patency for fluids.
The intensity of the hypergenic changes indicates
a positive correlation between the amplitude of fault
throws and a negative one with the depth of the bed incidence.
The coal thermally and weatheringly changed
is connected with the faults of the NW-SE run.
The fault run next to which the aggrading coal
changes dominate is close to the NWN-SES and W-E
direction. Because the faults of such a run in the USCB
are susceptible in nature and developed during the compressive
regime, their fissures are usually closed, cumulating
the friction heat. In the fault zones where there were no changes in the coal quality, the orientation of
faulting surfaces did not show the privileged run direction.
It is assumed that the hypergenic changes in coal
beds are generally connected with the inversion of the
Upper Silesian basin, which took place during the
Asturian phase of the Variscian orogenesis. The climax
of the weathering changes also occurred in the Upper
Carbon—Lower Triassic period, however, they could
have lasted up to the Paleogene.|