Geoscience Reference
In-Depth Information
Fig. 2.37 View of the
entrance of Dushnika Cave
underground lake can rise abruptly even to 13 m after
intensive atmospheric precipitations and snow melt-
ing. In this case, a river appears from the lower
entrance of the cave.
The most important faults are (Fig. 2.38 ):
Topilia Faults. They are two subparallel faults
situated northwards of the village of Breze, strike N
100-110. The southern one is well seen in the
morphology, the northern one is displacing Quater-
nary blockages, and this could be a reason to suppose
their recent activity.
Sulio Fault is a normal fault striking N 130-140.
It continues to the east, outside the studied area. The
southern block is subsided.
Ejdan-Breze Fault is a normal fault with right-
lateral component of the movements. The horizontal
displacement is evaluated at 250 m, while the vertical
one is 40-55 m. The western block is subsided. The
interpretation is (according to Paskalev et al. 1992 )
that the right-lateral movements appeared first and
lately, during the Illyrian Tectonic Phase, the vertical
displacement occurred. The fault is not displacing
Topilia Faults and other northwards located faults, but
it
Geological Background
Triassic and Jurassic autochthonous sediments crop
out in the area of Iskrets Karst Springs (Fig. 2.38 ).
These rocks represent a part of the northern limb of
Izdremets-Gubesh syncline. To the north of the vil-
lage of Breze, it is cut by a number of E-W oriented
faults. An important tectonic role is attributed to the
N-S trending Ejdan-Breze normal fault (Fig. 2.38 ).
Practically, the structures in the autochthonous sedi-
ments are controlling the underground water streams.
Svoge Allochtone is a structure built of the two
regional Breze and Iskrets overthrusts. In the area of
Iskrets Karst Spring, the Breze overthrust covers the
sediments of the autochthone. The overthrust repre-
sents a complicated structure, including a number of
overthrusted imbrications (Fig. 2.38 ). The plane of
thrusting is almost sub-horizontal, and only its frontal
part is inclined southward. The overthrust is com-
posed of Triassic and Jurassic sediments.
Iskrets Overthrust is the most important allochth-
onous structure in the area. It covers and is younger
than Breze Overthrust. It is built of Ordovician rocks.
Folds and faults were formed in its frontal part.
disturbs
the
structures
of
the
overthrusted
imbrications.
Tchernovodene Fault is one of the important tec-
tonic structures near Iskrets Karst Springs. Its northern
block is built of Babino Formation (Upper Anisian),
Milanovo Formation (Ladinian) and Rusinovdel For-
mation (Ladinian—Middle Carnian), and the southern
block
is
composed
of
the
sediments
of
Opletnia
Member
(Lower-Upper
Anisian).
The
performed
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