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Intensely lithified paleokarst deposits in Okno Cave,

Demänovská Valley (Slovakia)


Faculty of Education & Social Work, A35, University of Sydney, NSW 2006, Australia;

(Manuscript received November 3, 2006; accepted in revised form June 13, 2007)

Abstract: Lithified paleokarst turbidite deposits in Okno Cave, Demänovská Valley occur in cavities intersected by
the main relict fluvial passages of the cave. The deposits show a degree of diagenesis not normally associated with
lithified cave sediments with the development of spar-lined voids and diagenetic chalcedony. This indicates a period
of post-depositional burial before their exposure in the walls of the present cave. The deposits indicate the existence
of an ancient period of cave development and filling after the folding of the limestone but before the incision of the
Demänovská Valley. This is likely to have taken place in the Paleocene.

Key words: Paleokarst, caves intersecting paleokarst, Demänovská Valley, Okno Cave.


While much paleokarst has been reported from the Triassic
limestones of Slovakia (Činčura 1992, 1993, 1998; Činču-
ra & Köhler 1995; Činčura & Šucha 1992), there have
been few reports of paleokarst deposits as remnants in
caves or exposed in and intersected by the walls of caves.
Novotný & Tulis (2002) described Paleogene sandstones
and conglomerates in Skalné Okno Cave in the Slovenský
raj (Slovak Paradise) National Park. The deposits de-
scribed here appear to be the first examples reported from
Slovakia of paleokarst turbidite sediments filling ancient
caves that have been intersected by more modern caves.



The Demänovská Valley is one of a number of north-

south trending valleys cutting through the Nízke Tatry
Mountains (Low Tatras) in central Slovakia. An exten-
sive system of largely fluvial caves, the Demänovská
Caves, is developed in the limestone towards the north-
ern end of the valley 10 kilometers south of the regional
city of Liptovský Mikuláš. The caves include the show
caves Demänovská Cave of Liberty and Demänovská Ice

Geomorphological setting

The Demänovská Valley was excavated through the E-

W trending Nízke Tatry Mountains (Western Carpathians)
by the Demänovka River flowing north towards the Lip-
tovská kotlina Basin (Fig. 1). The entrance to Okno Cave

is located high in the eastern side of Demänovská Valley,
some 150 meters above the active bed of the Demänovka
River at an elevation of 916 meters above sea level
(Fig. 2).

Droppa (1966) recognised that Okno Cave represented

the highest and oldest, ninth level, in his sequence of
cave development in Demänovská Valley. He gave no
definite age for this level due to “lack of sufficient
evidence”, but suggested a Pliocene age because of “the
degree of weathering of the fluvial gravel” (Droppa
1966, p. 191). Orvošová (2005) suggested that the
incision of the adjacent Jánska Valley (Fig. 1), which is
incised through the same limestone as Demänovská
Valley, also occurred in the Pliocene.

Geological setting

In the Demänovská Valley area, Mesozoic marine sedi-

ments dipping to the north and northeast on the Krížna
Nappe overlie the “crystalline core” of the Low Tatra
Mountains (Fig. 3). Okno Cave is developed in the Trias-
sic Gutenstein Limestone. Biely (1992) indicated that
strata near the cave dip 30 degrees to the northeast. The
limestone at the cave entrance is massive with beds 1 m
or more thick. East of the cave entrance the limestone
dips at 30º towards 064º. Granites and crystalline meta-
morphic rocks crop out to the south of the limestone,
while to the northeast the limestone is overlain by Juras-
sic marls and sandstones.

Okno Cave

Okno (Window) Cave, with a plan length of 930

meters, is principally composed of former stream
passages, extending in an arc for some 600 meters south

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from its entrance (Fig. 4). The cave is almost horizontal
in long-section. In detail the northern and southern sec-
tions of the cave are structurally-guided rooms, while the
centre section is meandering, although still probably
structurally-guided in plan.

A fluvial origin for the main passages is supported by the

presence of well-developed scallops in the walls of Sieň
Smútočnej Vŕby indicating a northerly flow (“5” in Fig. 4,
Fig. 5A). Fluvial action is also indicated by large deposits

Fig. 1. Location map by P. Gažík generated from the Správa slovenských jaskýň, GIS system.

Fig. 2.  View of the Demänovská Valley looking to the South
from high on the eastern bank. The arrow indicates the location of
the entrance to Okno Cave. Photo P. Bella.

of strongly cemented clastic sediments composed of coarse
sand and rounded cobbles (“6” in Fig. 4, Fig. 5B).

In addition to the dominant fluvial elements, the cave

ceiling intersects a number of elliptical cupolas (“4” and
“7” in Fig. 4, Fig. 5C). These are oriented obliquely to
the fluvial passages and appear to be guided by a differ-
ent set of vertical joints (striking N-S and E-W) to those
that guide the fluvial passages (striking generally NW-
SE and NE-SW). Marušin (2003) noted that NW-SE and
NE-SW trending structures guided the development of
the Demänovská Cave system as a whole.

The paleokarst deposits occur in a wall pocket, a small

NE-SW trending passage and a small E-W trending
passage that appear to be morphologically more related
to the cupolas than to the fluvial passages.


In addition to field observations, samples were

collected and examined as polished blocks and in thin
section under a polarising stereomicroscope and a
petrographic microscope. A sample of the fluvial
sandstone from Location 6 (Sk11) was also thin
sectioned and examined for comparison.

Deposit 1

This deposit is located in an alcove in the southwest-

ern wall of Okno Cave, about 25 m from the entrance

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(“1” in Fig. 4). It partly fills the remnant of a cupola-
shaped cavity 2.5 m high (Fig. 6A). The upper third of
the cavity is dome shaped. Below the dome, there is a
distinct notch in the southern wall where the cavity
reaches its greatest width of 1.5 meters. In the northern
wall, a less distinct notch forms the top of a well-devel-
oped inward-sloping plane in the wall, similar to the fa-
cetten of Kempe (1975). The top of the deposit just fills
the notch (Fig. 6B).

The deposit is 1.3 m thick at its broken (eroded) outer

edge and consists of three units, an upper dark laminated
unit, 250 mm thick (Sk6), a middle brown unit, 600 mm
thick (Sk7) and a lower brown sandy unit, 450 mm thick
(Sk8). The upper surface of the deposit, partly covered by

a thin veneer of flowstone, dips to the north-northeast
(24º towards 028º). The strata in the top unit also dip to
the centre of the cavity, forming distinct dish-shaped
bedding (Fig. 6B). On the southern side of the deposit,
the layers of the middle unit are folded, dipping to the
south (Fig. 6C).

Dark laminated unit, Sk6

The thin section of the dark laminated unit (Sk6)

shows very finely laminated grey-brown lime mudstone
with some pyrolusite dendrites. It consists almost
entirely of calcite with poorly developed laminations.
Micro faults displace some laminae (Fig. 8A).

Fig. 3.  Geological map of the Demänovská
Valley modified after Biely (1992).

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Apart from calcite, there are a few elongate brown biotite

grains present and under high power rare, very fine quartz
grains are resolved. The quartz grains undergo undulate
extinction and some have well-developed crystal faces.

Middle, brown unit, Sk7

The middle brown unit (Sk7) is a finely graded carbon-

ate siltstone/sandstone with cyclic laminae. Major lami-

Fig. 4.  Okno Cave, modified after Droppa (1953) showing
location of features described in text. 1 – Paleokarst deposit 1,
2 – Paleokarst deposit 2, 3 – Paleokarst deposit 3, 4 – Elliptical
cupola with N-S orientation just inside cave gate, 5 – Scallops in
Sieň Smútočnej Vŕby, 6  – Fluvial sediments in Pekelná Chodba,
7 – Elliptical cupola with E-W orientation.

nae are approximately 5 mm thick and graded. Minor
laminae are approximately 0.5 mm thick, finer grained
and darker (tan coloured). Bedding is cross-cut by solu-
tion voids, some open and some filled with spar
(Fig. 8B).

The siltstone is almost completely composed of cal-

cite. Non-carbonate grains consist of some elongate
brown biotite grains aligned parallel to bedding, and
rare, angular, quartz grains that show little sign of trans-
port. Lines of partially interconnected voids traverse the
sample, mostly running obliquely across bedding. Some
follow micro faults.

Brown sandy unit, Sk8

The brown sandy unit (Sk8) is coarser grained than the

other two units and consists of interbedded very coarse
and finer sands (Fig. 8C). Some liesegang banding is de-

The unit is composed of large angular to subangular

clasts up to 1 mm in a fine brown carbonate matrix
(Fig. 8D). The large clasts include: calcite crystal frag-
ments, polycrystalline calcite aggregates, limestone li-
thoclasts, slate lithic fragments, silicic volcaniclastic
fragments and quartz. The striking characteristics of this
unit are its poor sorting, the variety and immaturity of
the larger clasts and the presence of matrix, rather than
carbonate cement between the clasts.

Deposit 2

This deposit in located in a side tube off a north-south

trending branch from the southern end of Výskumná
chodba (“2” in Fig. 4). The tube containing the deposit
has an unusual triangular profile, modified by two dis-
tinct notches, and is 1.6 m wide at its base (Fig. 7A). The
deposit is situated 100 mm below a flowstone false floor.
The upper surface of the flowstone is 100 mm below the
top (apex) of the tube (Fig. 7B).

The deposit dips to south and has a maximum thick-

ness of 130 mm at its southern side. It is fine-grained and
strongly indurated. The upper third of the deposit con-
sists of a single bed with visible laminations (Sk14),
while the lower third consists of four thinner beds. Sam-
ple Sk10 was collected from the lowest bed on the north-
ern side of the deposit and sample Sk14 comes from the
centre of the uppermost bed, as indicated in Fig. 7B.

Massive mudstone unit, Sk10

In hand specimen, the lower third of Sk10 is a finely

laminated light tan mudstone, while the upper two thirds
are massive grey-brown mudstone. In thin section, rhyth-
mic bands, 2 mm thick, of fine and finer carbonate mud,
intersected by a flame structure of slightly coarser car-
bonate silt (Fig. 8E) become apparent. This mudstone is
almost entirely composed of calcite, with rare grains of
biotite and quartz resolved at 500 .

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Fig. 5.  A – Scallops in western wall of in Sieň Smútočnej
Vŕby, Location 5 in Fig. 4; B – Fluvial sediments in Pekelná
Chodba at Location 6 in Fig. 4. Note rounded cobbles in upper
and lower conglomerate layers and concretionary sand balls in
centre coarse sandstone layer. Black squares on scale = 10 mm;
C – Composite image of elliptical cupola located just south of
gate at Location 4 in Fig. 4. Axis of cupola is oriented approxi-
mately N-S, oblique to the passage. Long axis of cupola is ap-
proximately 10 m.

Laminated mudstone unit, Sk14

In hand specimen, Sk14 is grey mud with tan laminae

1 mm thick or less. There are numerous irregular second-
ary cavities up to 2.5 mm across, some forming small
branching networks. In thin section, very fine layers and
silty layers up to 4 mm thick are resolved. The layers are
curved, forming convolute bedding (Fig. 8F). The fine lay-
ers are almost entirely calcite with rare quartz and biotite
grains. Quartz and biotite are just slightly more abundant
in the coarser layers. Some of cavities are lined with fine
spar that penetrates into the rock mass as sparry veins.

Deposit 3

Deposit 3 is located in a side tube off the southwestern

wall of Okno Cave, 4.5 meters northwest of Deposit 1
(“3” in Fig. 4). Here an approximately E-W trending pas-
sage (axis 104º) extends to the west from the wall of the
main passage. This passage is 2.3 m high. It has a hemi-
spherical ceiling with walls that start off vertical, then
slope to the northeast and then become vertical again near
the cave floor (Fig. 7C). The deposit consists of three sepa-
rate remnants of lithified sediment, one at floor level and
the other two forming false floors across the tube.

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Basal rough unit, Sk15

The lowest, rough unit (Sk15) is 100 mm thick. It has a

rough surface texture in the field, suggesting that it is
coarse grained. In hand specimen, the rock surface appears
finely pitted and some elongate black grains are visible.
The bulk of the rock appears to be a homogeneous grey
mudstone with a flaky surface texture, similar to that seen
on quartzites.

Three samples were collected from the basal rough

unit: Sk15A from the top third of the unit, Sk15B from
the middle third and Sk15C from the bottom third.

Sk15A (Top)

The top third of the basal rough unit (Sk15A) is a fine

sparite with poorly-defined graded beds, 10 mm thick. It
consists almost entirely of blocky spar grains (Fig. 9A).
Under high power, the spar is resolved as blocky rhombs
and rhomb fragments. The non-carbonate component
consists of a few aligned biotite flakes, tiny rare elongate
quartz grains and extremely rare muscovite flakes. A line
of secondary cavities extends across the sample. These
cavities are approximately 1 mm long and poorly rectan-
gular in shape.

Fig. 6.  Deposit 1:  A – Wide-angle view of alcove, looking
NW. Note dome-shaped upper profile, distinct notch and well-
developed facet on RHS. Scale is 1 m folding rule; B – Detail
showing SW side of deposit. Pocket knife for scale is 85 mm
long;  C – Detail of southern side of deposit. Note folding of
bedding in unit 2, possibly due to slumping above and to the
right of scale bar. Note also dish-shaped bedding of unit 1 in
top centre of the deposit. Black squares on scale = 10 mm.

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Fig. 7.  Deposits 2,3:  A – Wide-angle view
of Deposit 2 looking W, note triangular pro-
file. Arrow points to deposit, shown in detail
in 7B. Scale is 1 m folding rule; B – Detail
of Deposit 2. Deposit 2 is the layer with lami-
nations below the scale. Arrows indicate
sources of samples Sk10 and Sk14. Black bar
on scale is 20 mm long; C – Wide-angle
view of Deposit 3 looking NW. Passage is
2.3 m high and 1.3 m wide at base. Geologi-
cal hammer for scale is near arrow indicating
location for sample Sk15; D – Detail of up-
per part of Deposit 3, showing false floors
and locations for samples Sk16 and Sk18.
Black squares on scale = 10 mm.

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Fig. 8. Thin sections: A – Deposit 1, dark laminated unit, SK6, Crossed Nicols, 6.4 . Note grading and fault; B – Deposit 1, middle
brown unit Sk7, Crossed Nicols, 6.4 . Note graded laminae, aligned voids and dendrites on fine mud layer; C – Deposit 1, brown
sandy unit Sk8, Crossed Nicols, 6.4 . Note large angular clasts and the variety of clasts: calcite crystal fragments, composite calcite
grains, quartz, lithic fragments, biotite slivers, poor sorting and grading; D – Deposit 1, brown sandy unit Sk8, Crossed Nicols, 40 .
Note large angular quartz grains, lithic clasts and matrix support; E  – Deposit 2, lower unit Sk10, Crossed Nicols, 6.4 . Note coarse
carbonate lamina at top and fine carbonate lamina at bottom; F – Deposit 2, upper unit Sk14, Crossed Nicols, 6.4 . Note convolute
bedding and irregular cavities.

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Fig. 9. Thin sections: A – Deposit 3, lower unit Sk15A, Crossed Nicols, 6.4 . Note poorly defined laminae and line of voids close to
bottom of image; B – Deposit 3, lower unit Sk15B, Crossed Nicols, 6.4 . Note distinct laminae; C – Deposit 3, lower unit Sk15C,
Crossed Nicols, 6.4 . Note laminae coarser at bottom of sample and voids; D – Deposit 3, middle unit Sk16, Crossed Nicols, 6.4 .
Note newer dripstone layers at bottom of image “A”, older dripstone structure “B”, mottled micrite with voids in centre of image “C”
and poor lamination at top of image; E – Deposit 3, upper unit Sk18A, Crossed Nicols, 6.4 . Note section through straw a bottom of
image “A”, then flowstone layers “B” and interlaminated mudstone and flowstone at top “C”.

Sk15B (Middle)

The middle third of the basal rough unit (Sk15B) is a

coarser sparite with distinct laminae 3 mm thick, some of
which are graded (Fig. 9B). The spar has a granitic texture,
consisting of a mosaic of intergrown angular grains. Well-
formed calcite rhombs are absent. The non-carbonate com-
ponent is more prominent than in Sk15A. In addition to
aligned small biotite flakes, fine slivers of quartz and rare
muscovite flakes, there are also subangular quartz grains
up to 0.25 mm and a few biotite flakes up to 0.5 mm.

Sk15C (Bottom)

The lower third of the basal rough unit (Sk15C) is a

slightly coarser version of the overlying Sk15B. It has
some thicker laminae, up to 4 mm thick and a 3 mm thick
distinctly coarse lamina at its base (Fig. 9C). Under high

power the spar grains are coarser and less well sorted
than in Sk15B, consisting of rhombs of various sizes and
smaller calcite fragments. A few small, square, opaque
rusty grains, apparently limonite pseudomorphs after py-
rite are scattered through the sample.

The non-carbonate component of Sk15C consists of an-

gular grains of quartz with undulose extinction, aligned
biotite flakes, and rare small flakes of muscovite. Rare,
small, apparently diagenetic, patches of chalcedony are
visible at high power between the spar grains. Elongate
secondary spar-lined cavities, 3 mm long   0.5 mm wide,
are developed in the lower coarse lamina.

Middle dark unit, Sk16

The middle, dark unit (Sk16) is 30 mm thick (Fig. 7D)

and forms a false floor. It is dark grey and massive and
contains many small cavities up to 2 mm across and one

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larger cavity 13 mm across. Tiny golden sparking grains
are visible on broken surfaces. Under a stereomicroscope
these are seen to be the faces of biotite and muscovite
flakes. The middle dark unit is overlain by a thin lami-
nated unit that proved impossible to sample.

A finely-laminated layer of dripstone, that may be very

recent in origin, covers the bottom 1—2 mm of the speci-
men (“A” in Fig. 9D). On the left side between the drip-
stone and the specimen proper, there is a layer of dripstone
that appears to be part of the original sequence (“B” in

Fig. 10. Thin sections; A – Deposit 3, upper unit Sk18B,
Crossed Nicols, 6.4 . Note pelletisation by spar surrounding
siltstone, spar-lined voids, and poorly sorted siltstone making
up main part of specimen. “A” points to bone fragment; B –
Pelletised entrance facies deposit from Cliefden Caves, NSW
Australia. Crossed Nicols 6.4 . Note how bodies of siltstone
are completely surrounded by invading spar resulting in pel-

lets of siltstone in a sea of spar; C – Coarse fluvial sandstone, Sk11, from Location 6 in Fig. 5, Crossed Nicols, 6.4 . Note angularity of
clasts and presence of very immature clasts, such as books of biotite; D – Coarse fluvial sandstone Sk11, Crossed Nicols, 50 , showing
zoned spar cement. Note how the cement goes to extinction in irregularly shaped zones (dark patch extending from left to right in frame).

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Fig. 9D). The main component of the sample appears to
fill irregularities in the surface of this dripstone.

The bulk of the specimen is a poorly-sorted wacke with a

mottled appearance (“C” in Fig. 9D). Larger grains include
calcite crystal fragments and less-common quartz grains
with undulose extinction in a fine brown matrix. Biotite
and muscovite flakes, mostly seen end-on, show no pre-
ferred orientation. At 200 , the matrix resolves as angular
calcite grains of varying size along with some biotite flakes,
muscovite flakes and angular quartz grains. Secondary spar-
lined cavities, up to 4 mm   1mm, form in chains across the
specimen, linked by nascent sparry veins.

Upper porous unit, Sk18

The upper false floor (Sk18, Fig. 7D) consists of a thin

layer of flowstone varying in thickness from 5—10 mm
(Sk18A) overlying remnants of a fine light brown silt-
stone penetrated by many irregular voids up to 10 mm,
some of which are spar-lined (Sk18B). As with Sk16, tiny
golden sparking grains are visible on broken surfaces of
Sk18B, similarly, under a stereomicroscope these are
seen to be the faces of biotite and muscovite flakes. The
temporal relationship between the flowstone and the rest
of the deposit in unclear.

Flowstone, Sk18A

This sample consists of dripstone layers underlying

thin layers of mudstone interbedded with flowstone
(Fig. 9E). The base of a small stalactite, with a
monocrystalline straw centre, dominates the lower left-
hand side of the specimen (“A” in Fig. 9E). This grows
on an older flowstone layer (“B” in Fig. 9E).

In the top of the specimen (“C” in Fig. 9E) mud layers

occur, interbedded with dripstone. The mud layers con-
tain small, mostly elongate, grains of quartz, biotite and
muscovite in a matrix of very fine brown micrite.

Porous siltstone Sk18B

At a gross scale, Sk18B appears to consist of rounded

clumps (almost pellets) of poorly sorted brown siltstone,
separated by interconnecting zones of spar (Fig. 10A).
The pellets and the intact areas of siltstone, consist of
murky brown partially-recrystallized micrite containing
scattered grains of quartz and biotite flakes.

The spar zones are interspersed with cavities up to

2 mm across lined with large spar crystals, some up to
1.5 mm long. A few large clasts are interspersed within
the spar zones including angular and rounded quartz up
to 0.5 mm, biotite flakes up to 0.5 mm, and one elongate
bone fragment also approximately 0.5 mm long.

Sk18B shows many of the characteristics that Osborne

(1978) attributed to the progressive cementation of en-
trance facies deposits: the gradual removal of mud by per-
colating vadose water and its replacement by spar. This
frequently results in the separation of the initial porous
silty matrix into pellet-like zones. While the overall tex-

ture of Sk18B is similar to the sediment described by Os-
borne (1978) shown in Fig. 10B, the mudstone within the
pellets in Sk18B is significantly more cemented than that
in the Australian sample, which is quite porous. The spar
crystals surrounding the pellets are larger and more euhe-
dral in Sk18B than those in the Australian sample.

Coarse fluvial sandstone (Sk11)

The fluvial sandstone from location 6 is coarser, signifi-

cantly less mature and has distinctly different cement to
the paleokarst deposits (Fig. 10C,D). It consists of rectan-
gular to subangular grains, up to 3 mm in size, of quartz
with undulose extinction, polycrystalline quartz, weath-
ered K feldspar, gneissic and schistose lithoclasts, books
of biotite and a few limonitic opaques. While most of the
grains are subangular, some quartz and lithic grains are
subrounded. The fabric is grain supported. Between the
grains, there is white, massive spar cement that goes to ex-
tinction in zones (Fig. 10D). This coarse spar cement is
distinctly different from the matrix found in the coarser
units of the paleokarst sequences (e.g. Sk8 and Sk16) or
the cement in the entrance facies (Sk18B).


Genesis of the paleocaves

The simplest interpretation of the cavities containing

these deposits is that they are dip-tubes formed by an early
phase of meteoric speleogenesis that was guided by a dif-
ferent set of joints to those that guide the modern cave.

The cavities containing the deposits have a number of

unusual features, which suggest they are not dip-tubes
and may have a different origin. The facet in the cavity
containing Deposit 1 and the triangular shape of the tube
at Deposit 2 are not typical of phreatic dip-tubes. Taken
together with the large cupolas, which share the same ori-
entation, these features suggest that it is worth investi-
gating the possibility of a hypogene origin for the an-
cient cave containing the paleokarst deposits and for
other high-level caves in the Demänovská Valley.

Environment of deposition

With the exception of the upper unit in Deposit 3, the

lithified sediments in Deposits 1, 2 and 3 are upward fin-
ing sequences. The three units from Deposit 1, the two
units from Deposit 2 and the lower unit from Deposit 3
have sedimentary features characteristic of cave turbidites
(Osborne 1983, 1984). They are fine distal laminates,
graded-bedded units and proximal poorly-sorted sandy
units. The coarser organized and disorganized conglomer-
ate facies are not present. The middle unit from Deposit 3
(Sk16) is most likely a proximal turbidite, formed by rela-
tively fine-grained sediment slumping into the phreas
from an entrance facies talus cone, i.e. the fine-grained
equivalent of a disorganized conglomerate.

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The upper unit from Deposit 3 (Sk18) consists of speleo-

them and a mottled, porous, poorly sorted siltstone con-
taining large quartz grains and a bone fragment. Sk18 is
most likely a lithified entrance facies deposit, deposited
and cemented in the vadose zone.

Turbidity currents in caves result from slumping of ma-

terial into a low-energy phreatic cave environment. The
presence of coarse allochthonous grains indicates a sur-
face source, with the sediment entering the cave via an
entrance facies cone that slumped into the ponded water.
The folding in the middle unit of Deposit 1 is consistent
with slumping in a phreatic environment.

Previous reports of cave turbidites have been from

non-fluvial caves. Marine turbidites (caymanites) have
been reported from modern and ancient flank-margin
caves (Korpás 2002) and freshwater turbidites from low
energy maze caves (Osborne 1983). Turbidites have not
been reported among the sediments found in the
presently active parts of Demänovská Caves, nor are they
likely to have been deposited under the fluvial condi-
tions indicated by the morphology and sediments found
in Okno Cave proper. The turbidites indicate that the
Okno paleocave had a low energy phreatic environment
quite different from that of both “modern” Okno Cave
and the modern Demänovská Cave system. The paleo-
karst turbidites formed in still phreatic lakes like those
found in modern low energy phreatic caves, many of
which have or are suspected to have a hypogene origin
(see Klimchouk 2007).

Provenance of the sediment

The larger clasts in the brown sandy unit (Sk8) include

both autochthonous (single crystal and polycrystalline
calcite fragments) and allochthonous (quartz, biotite and
lithic) grains. The coarse calcite fragments are derived
from either the disintegration of speleothem and/or
hydrothermal calcite. The allochthonous grains are simi-
lar to the more mature clasts in the coarse fluvial sand-
stone (Sk11).

The only significant non-carbonate grains in the finer-

grained turbidite lithologies are quartz, muscovite and
biotite. The micas are in the form of plates, seen end-on
in thin section as elongate grains. With the exception of
the bone fragment, the non-carbonate grains in the
entrance facies are similar in composition to those in the

The composition and shape of the non-carbonate

grains are consistent with a siliceous tectonized plutonic
or dynamic metamorphic origin. The maturity of the
grains, even in the entrance facies, suggests a significant
amount of transport, presumably on the surface before
deposition in the caves. Alternatively, the mature non-
carbonate grains in the paleokarst deposits could be
reworked grains derived from older rock units.

The maturity of the non-carbonate grains from the

paleokarst deposits contrasts with the low maturity and
angularity of the clasts in the coarse fluvial sandstone
(Sk11), which is likely to be derived directly from the

crystalline core of the Low Tatras. The lack of feldspar
among the coarse fractions and the lack of clay in the
fine fractions would seem, however, to rule out such an
origin for the paleokarst deposits. Feldspar is not only
present in the coarse fluvial sandstone but feldspar and
clays are also common components of modern fluvial
sediments in the Demänovská Caves (J. Psotka, Pers.


In all of the turbiditic specimens (Sk6, Sk7, Sk8, Sk10,

Sk14 and Sk15), the micrite of the lime mudstone matrix
has undergone neomorphism to form irregular grains of
microspar. They frequently surround relict patches of
micrite as described by Bathurst (1975).

Spar-lined voids and nascent sparry veins occur in

most of the paleokarst sediments. These are largely
unrelated to the depositional fabric of the rocks. In the
terminology of Choquette & Pray (1970), these voids are
“not fabric selective mesopores”.

The neomorphic texture of the matrices, the presence

of spar-lined voids, the development of nascent sparry
veins and the presence of diagenetic chalcedony all
indicate a degree of diagenesis not normally seen in
lithified cave sediments. The contrast between the
lithified entrance facies (Sk18B) and the Australian
example (Fig. 10A,B), suggest that Sk18B may have also
undergone a higher than normal degree of diagenesis.
There is no evidence for unusual diagenesis in the coarse
fluvial sandstone (Sk11). This suggests a period of burial
before the excavation of the present fluvial cave and the
deposition of the fluvial sandstones and conglomerates.

Constraints on the age of the paleocaves and deposits

The deposition of the paleokarst sediments is at a gross

level constrained in time between a minimum age set by
the excavation of Demänovská Valley and a maximum
age set by the tectonic processes that resulted in the dip
of the enclosing limestone beds.

The limestone beds are inclined as the front of the

Krížna Nappe, produced by north-south compression at
approximately 85 Ma during the Cretaceous (Biely &
Bezák 1997). This means that the turbidite paleokarst
deposits and the cavities they occupy can be no older
than Late Cretaceous in age.

The difference in maturity between the non-carbonate

clastics in the paleokarst deposits and those in the fluvial
sediments suggest that the non-carbonate grains in the
paleokarst deposits entered the paleocaves at a time when
the crystalline core of the mountains was largely covered.
The paleocaves were close to the surface at this time and
contained phreatic lakes where turbidites were deposited,
and airspace, perhaps due to a falling water table, where
flowstone and dripstone were deposited.

The diagenesis of the deposits suggests that a phase of

subsidence followed. The paleocaves, and the sediments
in them, were buried and exposed to circulating pore wa-

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ter. Burial was most likely caused by deposition of the
Central Carpathian Paleogene Basin of Gross et al. (1984).

Uplift and erosion during the Pliocene (Kadlec et al.

2004) initiated the modern phase of cave development
and incision by the Demänovka River. Okno Cave and
its fluvial sediments formed early in this phase, intersect-
ing the paleocaves and paleokarst deposits.

The paleocaves and paleokarst deposits can be no older

than 85 Ma, and no younger than 2 Ma, and given their
burial history are most likely to have formed in the Paleo-
gene or Late Cretaceous. This suggests a correlation with
the Paleoalpine paleokarst period of Činčura & Köhler
(1995) with the paleokarst deposits in Okno Cave repre-
senting an underground equivalent of the surface paleo-
karst features Činčura & Köhler describe.

Orvošová et al. (2004) described hydrothermal pale-

okarst calcite from Silvošova Diera Cave, a small cave
located at an elevation of 1446 m some 10.8 km south-
east of Okno Cave (Fig. 1). They proposed that this cal-
cite was a product of hydrothermal karstification in pre-
Pliocene, most likely Paleogene times. Alternatively, if
the paleocaves containing the deposits are hypogenic
they could have formed at the same time as Silvošova Die-
ra Cave, which has similar age constraints (Orvošová et
al. 2004; Orvošová 2005).

In either case, the constraints on cave development, the

difference in provenance between the deposits and more
recent relict sediments and the evidence for burial indicate
that the sediments are most likely Paleocene in age.


The strongly lithified paleokarst deposits in Okno

Cave were deposited under low energy phreatic condi-
tions, quite different from the depositional environment
found in the active parts of the Demänovská Cave system
today or indicated during the evolution of “modern”
Okno Cave. The depositional environment had sufficient
connection to the surface to allow the entry of relatively
mature allochthonous grains from a granitic source.

After deposition, the paleokarst deposits were subject to

significant diagenesis, most likely due to burial of the
karst landscape under Paleogene basinal sediments. The
paleokarst deposits are probably Paleogene or Late
Cretaceous in age and are likely to correlate with the
Paleoalpine paleokarst period of Činčura & Köhler (1995).

There are some features of the sediments, and the

cavities they fill, which are suggestive of hypogene
karstification. This requires further investigation.

Acknowledgments:  The first deposit was discovered, ini-
tial observations made and samples recovered in August
2001, while the author was on a field trip with Prof P.
Bosák and Dr J. Kadlec of the Czech Geological Insti-
tute. The second deposit was discovered and observa-
tions made on August 1, 2005 with the assistance of Pavel
Stanik of the Správa slovenských jaskýň (SSJ, Slovak
Caves Administration). Josef Psotka of the SSJ discov-

ered the third deposit on August 30, 2005 while assisting
with fieldwork. Drs P. Bella and Dr L. Gaál of the SSJ
provided logistical support and assisted with local geo-
logical and geomorphological knowledge. Peter Gažik
assisted with the production of the location and cave
maps.  The initial discovery, later fieldwork and much of
the writing of the paper took place while the author was
visiting Slovakia on Special Studies Programs from the
University of Sydney. Preliminary findings from this re-
search were presented at the conference Výskum,
Využívanie a Ochrana Jaskýň 5 in September 2005 and
published in its proceedings (Osborne 2006). Rod Hun-
gerford prepared the thin sections. P.J. Osborne proofread
the text and figures. The paper was improved by sugges-
tions from the editor and referees.


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