Geoscience Reference
In-Depth Information
tectonic stress field axes keep their general orientation
and the consecutive dominant NW-SE direction of the
largest galleries in the cave. The main phreatic stage
of cave formation and especially the formation of the
large halls can be assigned to this period. The today
stress field has not impacted the galleries trend,
because the cave has been not active at least during
the last 0.7 Ma.
The comparison of the reconstructed tectonic stress
fields with the dominants directions of the galleries of
the Orlova Chuka Cave confirms totally the tectonic
control of the cave formation (Fig.
2.22
).
according to some authors) is considered as continu-
ation of the High Karst of Dinarides (Fig.
2.23
).
The lower part of the geological section is repre-
sented by terrigenous sediments of Permian to Lower
Triassic age. They are covered by carbonate sedi-
ments. Their accumulation began during the Middle
Triassic. Bauxites were formed in the same time. A
continuous sedimentation of neritic limestone fol-
lowed to Maastrichtian time. Jurassic pelagic lime-
stones with silicitic layers occur in the eastern part of
the Albanian Dinarides. This part (called also Val-
bone Subzone) is considered as an independent tran-
sitional element of uplifted Vermosh flysh, which
covers a period from Maastrichtian to Eocene.
At the end of the Eocene, the zone of the Albanian
Dinarides was deformed and thrusted to the south
over the zone Krasta-C ukali. From structural point of
view, the Albanian Dinarides are a monocline dipping
northwest. The large Valbone anticline is located to
the northeast and the large Malesia-Madhe syncline is
situated to the northwest.
The region in which the expeditions of the Bul-
garian Speleological Federation worked during four
consecutive years (beginning from 1990) is a part of
the North Albanides. According to the age of the
more intense folding, the region belongs to the areas
deformed at the end of the Eocene. More detailed
structural and tectonic investigations in 1994 have
been carried out on the territory of the SE limb of
Malesia-Madhe syncline, and especially near its axial
part. The geology of this territory is represented
mainly by carbonate complexes of Lower Jurassic up
to Lower Cretaceous (Barremian-Aptian) age. The
results of the structural-geological studies were pub-
lished by Shanov (
1999
). Here, the tectonic control on
the karst formation in the studied area is discussed
following this publication.
Different-order faults determine the formation of
the tectonic block structure of the limestone massif.
They are long-term acting faults with quite explicitly
manifested neotectonic activity affecting the relief
and the karstic processes in the region. The recent
activity of some of the faults is manifested by con-
centration of earthquake foci along them (Fig.
2.24
).
The fault Rapsh- Boçani is quite active during the
recent tectonic stage (No. 4 in Figs.
2.24
and
2.25
).
It is clear, that energy accumulation occurs along
this fault, periodically being released by earthquakes
2.3
Tectonic Stress Control on Karst
Systems: Case Studies
The presented case studies are from different coun-
tries and different tectonic context had impacted the
formation of the karst systems. Nevertheless, the
tectonic control is always present and the contempo-
rary processes of karst evolution show clear rela-
tionship with the youngest fracturing, i.e., with the
recent tectonic stress field characteristics.
2.3.1
Albania: Tectonic Factor for Karst
Formation in the Albanian
Dinarides
2.3.1.1 Short Geological and Tectonic
Characteristics
The structural complex characterizing the exception-
ally complex geological structure of the not so large
Albanian territory is named by Albanian geologists
Albanides (Biçoku et al.
1978
). Both basic mega-
structural units of the Albanides—North Albanides
and South Albanides (related with the Helenides) are
separated by the Shkodra - Pejio transversal zone
representing an old paleogeographic province. The
tectonic domains display different deformation styles.
The External domain, where the presented studies
were performed, including Paleogene and younger
units of the Krasta-C ukali and other tectonic zones to
the west, has been affected by compression, mani-
fested in west-directed folds, thrust faults and oblique
strike-slip fault systems (Dilek and Koçiu
2004
). The
karst
of
Albanian
Dinarides
(Albanian Alps
zone
