Geoscience Reference
In-Depth Information
Fig. 3.43
Location of Lepenitsa Cave and geological map of the area (after Shanov et al.
2001
)
(A) Fallen and calcified to the floor stalagmites. The
perturbed stalagmites are an average length of 40 cm
with secondary overlay of thin sinter deposits—evi-
dence of the relative age of the deformation. In some
cases, on the horizontal fallen fragments was observed
the formation of small active stalagmites. The descri-
bed samples fell on flat, horizontal floor, which
excludes their secondary predisponation after failure.
(B) Inclined massive stalagmite lines covered with
a new generation of vertical stalagmites (Fig.
3.46
).
The inclined stalagmite series are up to 2.5 m high.
This seismotectonic phenomenon is formed in the dry
section of the cave without presence of fluvial sedi-
ments under the stalagmites and no signs of their
existence in the past. The subsidence of sediments is
excluded as a possible cause of inclination.
(C)
The detailed geomorphological study of the cave
and the statistical analysis of the geometry and ori-
entation of the deformed speleothems may prove the
coseismic origin of the deformations. In the first fossil
level (''The main gallery'') of Lepenitsa Cave, the
directions of 68 broken stalagmites or stalagmite
fragments were measured and a rose-diagram was
made. Most of the studied stalagmites were candle
shaped of average length of 40 cm and secondarily
recovered with thick sinter deposits. In some cases,
recent small active stalagmites developed upon the
broken ones. The selected samples have fallen down
on flat and stable horizontal floor, which excludes
their secondary disposition.
The diagram shows clearly expressed preferred
orientation (Fig.
3.48
). The maxima (360-370 g and
390-400 g) generally correspond to a direction
pointing to the town of Velingrad—the epicenter of
Open
fissures
in
massive
stalagmites
(Fig.
3.47
).
