Geoscience Reference
In-Depth Information
Fig. 2.9
Reconstructions of the tectonic stress fields (lower
hemisphere) using the shear joints groups from Fig.
2.8
.
a Paleocene deformations (Middle Laramian tectonic phase).
b Late Eocene deformations (Late Illyriyan tectonic phase).
c Neotectonic deformations
Fig. 2.10
Geological scheme of the karst area of Cherepish
(from the Geological map of Bulgaria, Sheet ''Vratsa'' 1991). The
position and the map of the Labirinta Cave are indicated. Lower
Cretaceous: 1—Lutibrod formation (oolitic and sandy lime-
stones); 2—Cherepish formation (massive organogenic lime-
stones); 3—Mramoren formation (marls with layers of clayey
limestones
4—Slivnitsa formation (massive limestones); Carboniferous—
Permian: 5—Vrana formation (breccia-conglomerates, conglom-
erates); 6—Buk formation (conglomerates, sandstones, siltstones,
argillites); Cambrian: 7—Berkovitsa group (metamorphosed
argillites, siltstones, marbles and sandstones); Fault structures:
8—overthrust; 9—fault
and
sandstones);
Jurassic—Lower
Cretaceous:
2.2.3
Physical Anisotropy
direction. Especially, the cave ''Labirinta'' is one of the
example of the tectonic control on the formation of
preferentially oriented galleries that follow the trend of
the open (tensional) fractures deduced from the
reconstruction using the shear joints. Here, the impact
of
The physical anisotropy of the rock massifs is the
variance of its physical characteristics, depending on
the direction of their measurement. The causes for the
rock anisotropy can be summarized, as follows (after
Uhov
1975
):
the
youngest
tectonic
stress
field
is
evident
(Fig.
2.10
).
