Geoscience Reference
In-Depth Information
Table 2.6
Reconstruction of the sequence of tectonic impact on the rocks of Bosnek Karst Region
Site
Pliocene-
Quaternary
Origin
Post-Oligocene
Contemporary
Method
Earthquake
22.05.2012
M
w
=5.6
N 43.65
0
E 23.00
0
Fault-plane
solution
T
k-n
3
dolomites
Shear joints
Striations
on
slickensides
T
k-n
3
dolomites
T
a
2
3
Shear joints
limestones
Shear joints
and
striations on
slickensides
T
a
2
4
limestones
tectonic stress axes—sub-horizontal E-W compres-
sion and N-S extension.
Due to the fact that some of the older karst forms
were cut and displaced, and because of the position of
the studied area between two very active seismic
zones in this part of the Balkans, we think that the
detected traces of young movements can be related to
a past seismic event (or events). The nearest recon-
structed
Earthquake is supporting the opening of the NW-SE
oriented fractures (Table
2.6
), which is the general
trend of the karst galleries of the caves.
The age of the left-lateral movement along fault
No. 2 (Fig.
2.44
) is not clear. This fault was known
from the geological mapping in scale 1:25,000 only
northeastwards from the karstified area. It displaces
sediments of Jurassic age. We discovered its exten-
sion toward SW and a slickenside with striations,
fault-plane
solution
from
2012
Pernik
