ArticlePDF Available

Palaeomagnetic research on karst sediments in Slovenia

Authors:

Abstract and Figures

We have conducted palaeomagnetic and magnetostratigraphic research on karst sediments in Slovenia since 1997. More than 2,000samples were taken and analysed in 36 different profiles at 21 locations in caves and on the surface. Standard palaeomagnetic analyseswere used (thermal and alternating field demagnetisation, magnetic susceptibility measurements, etc.). There is no evidence of youngermarine deposition than Eocene in the SW part of Slovenia. Younger sediments occur only in caves and very rarely on the karst surface(different soils and a few remains of terrigeneous sediments). Marine and terrestrial Tertiary to Plio–Quaternary deposition occurs in theSE and E Slovenia. Chronostratigraphy of cave sediments in SW Slovenia completed by Rado Gospodarič in the 1980s was basedon Pleistocene warm/cold cycles. Later Th/U dating indicated that speleothems from different caves in Slovenia are older. New datingprincipally results from palaeomagnetism and magnetostratigraphy of cave sediments calibrated, in some sites, by Th/U, palaentologicaland geomorphological analyses. Calibrated data contributed to the reconstruction of speleogenesis, deposition in caves, and indirectly tothe evolution of karst surfaces and succession of tectonic movements. The evolution of caves in the Slovenian territory took part withinone post-Eocene karstification period. This period continues to the present, and can be subdivided into individual, but not well limited,phases related to Cenozoic palaeogeographical changes. The period contains distinct phases of massive deposition in caves with as yetstill preserved sediments dated to about 5.4–4.1 Ma (Miocene–Pliocene), 3.6–1.8 Ma (Pliocene) and Quaternary, following the cessationof Miocene deposition in the Pannonian Basin in the central, E and SE Slovenia and post-Messinian evolution in the SW and W Slovenia.
Content may be subject to copyright.
International Journal of Speleology 39 (2) 47-60 Bologna (Italy) July 2010
Palaeomagnetic research on karst sediments in Slovenia
INTRODUCTION
Slovenia is situated in central Europe within
the junction of four principal geographical regions
belonging to two orographic systems (the Alps and the
Dinaric Mountains) and two basins (the Pannonian
and Mediterranean Basins). Karst in Slovenia has
developed on carbonate rocks which cover about
43% of its total surface. According to the general
morphological and hydrological conditions, three
principal karst areas (Fig. 1) can be distinguished:
extensive Alpine (Julijan Alps and Kamnik–Savinja
Alps) and Dinaric karsts (Dinaric Mountains), and
Isolated Karst (separated patches of small karst areas
surrounded by nonkarst). The Slovene Dinaric region
of Kras (Karst) is also known as Classical Karst, where
investigations of hydrology and caves started some
150 years ago. At the moment there are more than
9,400 caves which are entered in the Cave Register
of the Karst Research Institute (IZRK) ZRC SAZU in
1 Karst Research Institute, ZRC SAZU, Titov trg 2, 6230
Postojna, Slovenia
2 Institute of Geology AS CR, v. v. i., Rozvojová 269, 165 00
Praha 6, Czech Republic
Zupan Hajna N., Mihevc A., Pruner P., Bosák P. 2010. Palaeomagnetic research on karst sediments in Slovenia. International Journal of
Speleology, 39(2), 47-60. Bologna (Italy). ISSN 0392-6672.
We have conducted palaeomagnetic and magnetostratigraphic research on karst sediments in Slovenia since 1997. More than 2,000
samples were taken and analysed in 36 different proles at 21 locations in caves and on the surface. Standard palaeomagnetic analyses
were used (thermal and alternating eld demagnetisation, magnetic susceptibility measurements, etc.). There is no evidence of younger
marine deposition than Eocene in the SW part of Slovenia. Younger sediments occur only in caves and very rarely on the karst surface
(different soils and a few remains of terrigeneous sediments). Marine and terrestrial Tertiary to Plio–Quaternary deposition occurs in the
SE and E Slovenia. Chronostratigraphy of cave sediments in SW Slovenia completed by Rado Gospodarič in the 1980s was based
on Pleistocene warm/cold cycles. Later Th/U dating indicated that speleothems from different caves in Slovenia are older. New dating
principally results from palaeomagnetism and magnetostratigraphy of cave sediments calibrated, in some sites, by Th/U, palaentological
and geomorphological analyses. Calibrated data contributed to the reconstruction of speleogenesis, deposition in caves, and indirectly to
the evolution of karst surfaces and succession of tectonic movements. The evolution of caves in the Slovenian territory took part within
one post-Eocene karstication period. This period continues to the present, and can be subdivided into individual, but not well limited,
phases related to Cenozoic palaeogeographical changes. The period contains distinct phases of massive deposition in caves with as yet
still preserved sediments dated to about 5.4–4.1 Ma (Miocene–Pliocene), 3.6–1.8 Ma (Pliocene) and Quaternary, following the cessation
of Miocene deposition in the Pannonian Basin in the central, E and SE Slovenia and post-Messinian evolution in the SW and W Slovenia.
Keywords: Magnetostratigraphy, dating, cave sediments, Dinaric Karst, Alpine Karst, Isolated Karst, karst periods, karst phases
Received 6 April 2009; Revised 29 July 2009; Accepted 2 September 2009
Postojna, and the Speleological Association of Slovenia
(JZS); these data were used during our work.
Principal karst regions belong to the Southern Alps
(Julian Alps, etc.) and External Dinarides (part of
the Dinaric Mountain). They function as two totally
different morphological units, both with different
geology and relief evolution. This review of regional
geology and geologic evolution is summarized mainly
from Buser (1989), Vrabec & Fodor (2006), Placer
(1999, 2007) and Pirc (2007).
The SW part of Slovenia (External Dinarides)
is characterised by the lack of both marine and
terrestrial deposits younger than Eocene on the
surface, except for different soils and a few remains of
sediments in karst depressions (i.e. poljes). The last
marine deposition took part here during the Eocene,
when a thick pile of ysch siliciclastics was deposited.
Jurassic to Paleocene limestones were exposed on the
surface during the Oligocene to early Miocene within
complicated nappe / overthrust structures. The area
is dissected by prominent NW–SE-trending fault zones
of Dinaric direction. The Oligocene/Lower Miocene to
Quaternary period represented one terrestrial period
with prevailing surface denudation and erosional
processes. Therefore, only karst sediments found on
Available online at www.ijs.speleo.it
International Journal of Speleology
Ofcial Journal of Union Internationale de Spéléologie
Abstract:
Nadja Zupan Hajna1, Andrej Mihevc1, Petr Pruner2, Pavel Bosák2,1
Paper presented during the GSM-03 Symposium “Karst as a global phenomenon - a tribute to Derek Ford and
Paul Williams” at the 33rd International Geological Congress held at Oslo, August 6-14th 2008
48 Nadja Zupan Hajna, Andrej Mihevc, Petr Pruner, Pavel Bosák
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
the karst surface and in the subsurface preserve the
record of karst evolution and its age. Pannonian Basin
and marginal (intermontane tectonic) depressions
with Tertiary and Plio–Quaternary lls cover
substantial parts of the SE and E parts of Slovenia
(belonging both to Southern Alps and External
Dinarides). Triassic to Cretaceous carbonate rocks of
the Southern Alps were deformed into nappes during
Eocene–Middle Oligocene, forming mostly W–E-
trending structural pattern. Strong Cenozoic tectonic
activity and rotations in both regional geological units
affected the accelerated geomorphological evolution
and karst processes - especially speleogenesis (Zupan
Hajna et al., 2008a).
The research in the present paper covered all
the principal karst regions, from lowlands to high
mountains. The sites were located in the Dinaric Karst
(32), Julian Alps (2), Isolated Karst of the pre-Alps (1)
and Plio–Quaternary uvial sediments from the tectonic
Velenje Basin (1). The low number of non-Dinaric
locations is due to the lack of suitable karst sediments
there. Sites included both well-known and documented
deposits, as well as relatively unknown or newly found
locations in caves and on the surface. Karst sediments
represent an important source of information on the
evolution of tectonic and geomorphological units of
different sizes. The territory of Slovenia, with its karst
regions, long history of karst evolution, and relatively
complete knowledge of the karst sediments, represents
an ideal testing ground for comprehensive research
on individual inlling processes, their stages and
periods. The aim of the research was focused on the
time span of karst evolution, age of karst surfaces and
speleogenesis, and rates of processes.
Fig. 1. Location of studied sites in Slovenia and Italy. Dinaric Karst sites: Kras Plateau and surrounding area (1- Črnotiče proles, 2 – Briščiki, 3 - Kozina
prole, 4 - Divača prole, 5 – Jama pod Kalom, 6 - Grofova jama, 7 - Divaška jama, 8 - Trhlovca, 9 - Račiška pečina, 10 - Pečina v Borštu), Notranjski kras
(11 - Križna jama, 12 - Planinska jama, 13 - Postojnska jama, 14 - Zguba jama, 15 - Markov spodmol), Dolenjski kras (16 - Hrastje prole), Alpine Karst
sites: Julian Alps (17 - Jama pod Babjim zobom, 18 - Jama nad Planino jezero), Kamnik-Savinja Alps (19 - Snežna jama), non-karst sediments
(20 – Velenje prole) and Isolated Karst: Ponikovski kras (21 - Tajna jama). Map source: DMV 25, Geodetska uprava Republike Slovenije.
49Palaeomagnetic research on karst sediments in Slovenia
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
The rst systematic studies of cave sediments in
Slovenia were carried out during the archaeological
excavations of sediments in the entrance parts of
some caves (Brodar, 1966). More extensive and
detailed study of cave sediments was performed by
Gospodarič (1976, 1981, 1988). He compared cave
sediments from different sites and he used different
numerical and other dating methods (Franke & Geyh,
1971; Ikeya et al., 1983; Ford & Gospodarič, 1989)
to establish the age of deposits and to distinguish
different deposition phases in the subsurface. In the
Kras, he linked the karstication of the area with
glacioeustatic oscillations of the Adriatic Sea and the
global palaeoclimate changes during the Pleistocene.
He suspected that the cave sediments were not much
older than 350 ka.
A better understanding of cave sediments, their age
and the chronological sequence of speleologenetic
events was achieved by more concentrated dating by
the method (Zupan, 1991; Zupan Hajna, 1996; Mihevc
& Lauritzen, 1997; Mihevc, 2001a). Data showed that
speleothem growth corresponds to warmer periods
during the Pleistocene. Nevertheless there are large
numbers of speleothems older than the limit of the
dating method.
The study of cave deposits (Fig. 2) in Alpine caves and
in unroofed caves of the Kras (Mihevc & Zupan Hajna,
1996; Mihevc, 2001a) provided entirely new insights
into the age of karst sediments and introduced new
ideas concerning the development of karst and caves.
The application and interpretation of palaeomagnetic
analyses and magnetostratigraphy of cave sediments,
both clastic and chemogenic, which began on the Kras
in 1997, suggested substantial changes of time span
in which deposition took part in caves (e.g., Bosák
et al., 1998, 1999, 2000, 2004; Šebela & Sasowsky
1999, 2000; Audra, 2000; Mihevc et al. 2002; Zupan
Hajna et al. 2008a, b). Magnetostratigraphy data and
the arrangement of obtained magnetozones often
indicated ages of the cave ll from 1.77 Ma up to over
5 Ma.
METHODS
The present paper summarizes our results
from the period of 1997 to 2008; full details are
available elsewhere (Zupan Hajna et al., 2008a).
Our palaeomagnetic research included a total of 21
sites (19 in Slovenia and 2 in Italy) with 36 proles;
all except one were cave or karst surface sediments.
During the last ten years we did complex research
of karst sediments applying a number of geologic
methods: palaeomagnetism and magnetostratigraphy,
stratigraphy (numerical and correlated dating
methods including, palaeontology – fauna, pollen),
sedimentology, and mineralogy (X-ray diffraction).
Palaeomagnetic studies conducted in caves have been
applied to determine the age of sediments (principally
ne-grained deposits ne-grained sands, silts,
clays – and speleothems) based on magnetic polarity
(magnetostratigraphy) and/or palaeo-secular
variations, and on palaeoenvironmental applications
of mass-specic magnetic susceptibility (MS).
Palaeomagnetic analyses were completed in the
Laboratory of Palaeomagnetism, IG AS CR, v. v. i.
in Praha–Průhonice. Procedures were selected to
allow the separation of respective components of the
remanent magnetization (RM) and the determination
of their geological origin. Oriented hand samples
from consolidated rocks and speleothems were cut
into cubes of 20 x 20 x 20 mm and subjected to
alternating eld demagnetization (AF) and/or thermal
demagnetization (TD). Samples from unconsolidated
sediments were demagnetized only by AF.
The laboratory procedures yielded results about (see
Zupan Hajna et al., 2008a): mean palaeomagnetic
directions, directions of C-components (with normal
and reverse polarity), mean palaeomagnetic values
and standard deviations (Jn, kn). Basic magnetic and
palaeomagnetic properties were compiled in the logs.
Dating of cave sediments by the application of the
palaeomagnetic method is a difcult and sometimes
risky task, as the method is comparative in its
principles and does not provide numerical ages. There
exist two principal rules to obtain data for reliable
interpretations: (1) to apply only dense sampling in
the eld (high-resolution approach with sampling
distance of 2–4 cm; Zupan Hajna et al., 2008a), and (2)
to apply both complete step and/or eld procedures
offered by both demagnetization methods; the
application of complete analysis only to pilot samples
and shortened, selected eld/step approach, to other
samples did not offer sufcient data set (Bosák et al.,
2003). Correlation of the magnetostratigraphic results
we obtained, and the interpretations tentatively
placed upon them, has shown that in the majority of
cases, application of an additional dating method is
needed to either reinforce the palaeomagnetic data or
to help to match them with the geomagnetic polarity
timescale.
RESULTS
Cave deposits (both clastic and chemogenic)
provide a record of processes (Ford & Williams,
2007) and evidence which has not been preserved
on the surface in most of karst regions of Slovenia.
They can help to decipher the younger geological
and tectonic history. About 2,000 samples
have been sampled and processed by standard
palaeomagnetic analyses, and biostratigraphic
dating, mineralogical, petrological and
geochemical analyses, etc. Palaeomagnetic and
magnetostratigraphy studies, combined with other
dating and analytical methods, offer a surprisingly
new time frame for cave depositional processes
they showed that most of analyzed sediments can
be up to several millions of years old; which is in
accordance to the idea of Sasowsky (2007).
Sites with dated cave and surface karst sediments
are presented on Figure 1. Sites were located along
the Dinaric Karst (Kras Plateau and surrounding
area, Notranjski kras and Dolenjski kras). There
were also samples from 3 sites in the Alpine Karst,
one from Isolated Karst, and for comparison of the
results, one from non-karst area.
50
Kras Plateau
The Kras is a low NW–SE-trending limestone plateau
lying at the northernmost part of the Adriatic Sea,
known also as the Classical Karst (Kras). According
to its geological and geomorphological properties is
divided into several smaller units. Cave sediments
were studied from the Divaški kras, Nabrežinski kras,
Kozinski kras, etc.
The Divaški kras (Fig. 3) covers the SE part of the
Kras Plateau around Divača village. The evolution of
this karst is well demonstrated in caves at different
altitudes. On the surface at 400–440 m a. s. l., there
are numerous unroofed caves, proved by massive
owstone, and allogenic cave sediments, the largest
of them is 1.8 km long. Other caves are at different
depth; some of them like Divaška jama and Trhlovca
Cave are shallow. The deepest is Škocjanske jame
cave system with 18 km of known cave passages
at 317–156 m a. s. l. The sampling started at sites
of Divaški kras: Divača prole, Divaška jama and
Trhlovca Cave (Bosák et al., 1998). The results were
exceptionally good, even when obtained in rather
primitive conditions. They indicated that the cave lls
are substantially older than initially expected. This fact
was not in accordance with the previous karstological
models in Slovenia, but illustrated and proved the
new ideas and data obtained by numerical dating,
the discovery of unroofed caves and their dating by
geomorphic means (Mihevc, 1996). Nevertheless, the
interpretation of the magnetostratigraphic picture
was problematic, as there were no palaeontological
nds.
The Divača prole represented a nearly unroofed
cave with a partly disintegrated roof. The cave was
completely lled by uvial deposits. The prole was
older than 1.77 Ma, i.e. the top of the Olduvai subchron.
The geometry of the magnetozones could indicate an
age as great as about 5.23 Ma (base of normal /N/
polarized Thvera subchron within the Gilbert Chron).
The substantial age of the cave is supported by the
thin roof, indicating signicant thickness reduction of
limestone roof by chemical denudation.
Divaška jama and Trhlovca (Fig. 2D) are situated
in the SW part of the levelled surface of the Divaški
Fig. 2. Examples of sampled sites. (A): Postojnska jama Cave system – part of Umetni tunnel I prole in which the oldest uvial deposits in the system
were found; (B): Prole I in Grofova jama – bottom part with yellow montmorillonite clays; (C): Črnotiče II prole – unroofed cave lled by yellow uvial
sediments covered by red clay with owstone, sampling points are located by paper cards; (D): Prole of owstone layers in Trhlovca Cave, below this
prole, also uvial sediments were sampled; (E): Sampling with plastic boxes in unconsolidated sediments; example from Tajna jama.
Nadja Zupan Hajna, Andrej Mihevc, Petr Pruner, Pavel Bosák
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
51
kras. Numerous dolines occur on the surface above
the cave, but they are not directly connected to it. The
caves represent an approximately 700 m long relict
of an originally larger cave system formed at about
350 to 410 m a. s. l. In both caves there exists a lot
of speleothem from different times and the remains
of uvial deposits. The laminated sediments from
Trhlovca were attributed to the Günz (Gospodarič,
1981, 1988). The ll of Divaška jama represents one
of the clear examples of temporary interruption of
speleogenetic and cave-forming processes. Based on
our initial results (Bosák et al., 1998), the sediments
were dated around the Jaramillo N polarity subchron
within the Matuyama reverse (R) epoch. High-
resolution re-sampling of the whole prole changed
this interpretation. The arrangement of R and N
polarized magnetozones (Fig. 4) is clearly older than
1.77 Ma (Zupan Hajna et al., 2008a). Both caves
underwent a prolonged and complicated evolution.
It cannot be excluded that Trhlovca represents an
old fragment of a completely choked cave that was
later rejuvenated as the consequence of the evolution
of Divaška jama and its ll. It is also possible that
the cave sediments from Trhlovca and Divaška jama
may represent the equivalent of the ll of Divača and
Kozina proles (unroofed caves; for details see Bosák
et al., 1998; 2000).
Grofova jama is a cave situated just below the top
(275 m a. s. l.) of one of several small hills at the NW
edge of Kras Plateau, about 150 m above its levelled
surface. The hill may represent either tectonically
uplifted block or residual erosional high (Zupan Hajna
et al., 2008a). According to the morphology of walls and
passages, the cave was formed in phreatic conditions.
At one stage the cave was completely lled with K-rich
montmorillonitic (beidellite) clay when it was situated
at a much lower relative altitude. The sediment was
later partly washed out and covered with red terra
rossa-like clay, but still with high montmorillonite
content. In the sampled prole (Fig. 2B) we obtained N
and R polarities, and segments without any magnetic
signal (Zupan Hajna et al., 2008a). The character
and composition of cave ll clearly indicate that pure
beidellite clays represent in situ weathering products
Fig. 3. Shaded relief digital terrain model of Divaški kras with deep collapse dolines, ground plans of: Divaška jama, Kačna jama, Škocjanske
jame, and marked locations of studied sites: Divača prole, Trhlovca and Divaška jama. DEM data source: DMV 25, Geodetska uprava Republike
Slovenije and Cave Register of IZRK ZRC SAZU and JZS. Notice: well expressed linear features of the surface belongs to trafc lines.
Palaeomagnetic research on karst sediments in Slovenia
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
52
Fig. 4. Basic magnetic and palaeomagnetic properties of Divaška jama prole. Legend: Lithology: straight lines in grey – siltyclay, dots – sand,
waves in light grey – owstone, ┬ with dots – calcareous silt, boxes in dark grey – collapse structure; Polarity scale: black – normal polarized
magnetozones, white – reverse polarized magnetozones, grey – mixed polarity; MS – magnetic susceptibility; NRM – natural remanent
magnetization; D – declination; I – inclination.
Nadja Zupan Hajna, Andrej Mihevc, Petr Pruner, Pavel Bosák
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
53
of volcaniclastic material in humid and warm climates
of the tropical type, and volcaniclastic material was
relatively pure and ne-grained deposited in quite
thick pile over bedrock. The source of volcanic ash
should be found in some of Oligo–Miocene volcanic
centres around the Mediterranean, like Colli Euganei
and Marostica Hills (north Italy, 170 and 160 km to the
W) or the Smrekovec (north Slovenia, now about 100
km to the E). Therefore, we can anticipate relatively
great age of the ll (up to 35 Ma).
Podgorski kras and Matarsko podolje
The Podgorski kras is about 5 km wide and up to
15 km in length, a karst plateau between Slavnik
Mountain (1025 m a. s. l.) on the NE and littoral hills
on the SW. The plateau is separated from the Kras
on the NW by an important tectonic line with a drop
of about 50 m. Two proles of cave sediments were
studied in Črnotiče Quarry.
The Matarsko podolje is a 20 km long and 2–5 km
wide at valley-like karst surface. The surface is
dissected by a number of dolines. The longitudinal
section shows that the surface gently rises from about
490 m a. s. l. at Kozina village (in the NW) to 650 m
a. s. l. on the SE end. Cave sediments from Račiška
pečina and Pečina v Borštu were studied.
The Črnotiče Quarry is situated on the W margin
of the Podgorski kras, ca 6 km to the SE from the
Adriatic coast. The quarry is carved in the leveled
surface at 440 m a. s. l. Numerous caves have been
opened during quarry operations. Most of them were
completely lled by sediments. We sampled two
proles (Črnotiče I and Črnotiče II). The Črnotiče I
prole was composed of banded carbonates (cave
stromatolite; Bosák et al., 1999) with intercalations
of red clays (probable sh remains were not still
determined), deposited over corroded/eroded surfaces
of older, highly re-crystallized speleothems. The N and
R polarity magnetozones were interrupted by many
unconformities of unknown duration. Therefore, any
correlation with the geomagnetic polarity timescales
(GPTS) is problematic. Nevertheless, according to the
arrangement of individual magnetozones on standard
scales we can assume that the whole prole is older
than the top of the Olduvai event (1.77 Ma). The
interpretation of palaeomagnetic parameters (Bosák
et al., 1999, 2004) and nds of fauna at the Črnotiče
II prole (Horáček et al., 2007) clearly indicated that
the age of the Črnotiče I prole can easily be as great
as 4.2–5.2 Ma.
About 40 m to the south of the Črnotiče I prole a
new vertical prole in a side passage was exposed.
Črnotiče II prole (Fig. 2C) is about 7 m wide and
17 m high passage completely lled with sediments.
Laminated and cyclically-arranged uvial sediments
composed the lower part of the ll and were covered
by breccia of fragments of massive owstone. The
modern karst surface cuts across the owstones,
exposing them in the form of an unroofed cave. The
site is also characterized by a rich appearance of
fossil tubes of autochthonous stygobiont serpulid
Marifugia cavatica. U/Pb dating of Marifugia cavatica
was not successful. The arrangement of obtained
magnetozones site was originally interpreted as older
than 1.77 Ma, most probably belonging to the Gauss
Chron (2.581–3.58 Ma) or the normal subchrons
within the Gilbert Chron (4.18–5.23 Ma; Bosák et
al., 2004). Paleontological data enabled matching
the magnetostratigraphic record precisely with the
GPTS. The vertebrate record is composed mostly of
teeth enamel fragments of rodents and soricomorphs
(with Deinsdora sp., Beremedia ssidens, Apodemus
cf. atavus, Rhagapodemus cf. frequens, Glirulus sp.,
Cseria sp.) is obviously quite older: suggests the
Pliocene age MN15–MN16 (ca 3.0–4.1 Ma; Horáček
et al., 2007). The development of vertical drawdown
shafts with a predominance of later autochthonous
ll resulted from vadose speleogenesis caused by the
drop of karst water level related to tectonic uplift,
which followed tectonic unrest during the MN 15
to MN16b mammalian biozones. The results of the
sediment ages indicate the cessation of the main
phase of vertical speleogenesis in the vadose zone in
the area, which was connected with continuous uplift
and shift of active phreatic speleogenesis to lower
levels. After that, the intensive planation (Bosak et
al. 2004) was active on the surface, which led to the
formation of the levelled surface of the Podgorski kras
and to collapse of the roofs of horizontal caves.
Račiška pečina is the best dated prole of cave
sediments in Slovenia. It is located in Matarsko podolje.
The cave is 304 m long simple southwards dipping
gallery, a relict of an old cave system, which was opened
by denudation to the surface. The studied sequence,
13 m long, of banded owstones, is situated in the
southern part of the cave; about 200 m from present
entrance. The composite thickness of the sampled
prole (Fig. 5) reaches 634 cm, but the true thickness
of exposure is only about 300 cm. The sediments were
well dated by different methods. For the rst time,
the magnetostratigraphic sequence was correlated
satisfactorily with the GPTS by biostratigraphy
(Horáček et al., 2007). Based on mammalian fauna
analysis (assemblage with Apodemus, cf. Borsodia),
the age was determined to middle–late MN17 (ca 1.8–
2.4 Ma; Quaternary age is excluded). The boundary
of N and R polarized magnetozone within the layer
with fauna (F) was identied with the bottom of
Olduvai subchron (1.77–1.95 Ma). The short N chron
just below the Olduvai base was correlated with the
Reunion subchron (2.14–2.15 Ma) and in the lower
part of the prole, the following magnetozones were
correlated: the base of Matuyama Chron (2.150–
2.581 Ma) and the individual subchrons within the
dominantly normal polarized Gauss Chron (2.581–
3.58 Ma) = C2An.1n subchron (2.581–3.04 Ma),
Keana subchron (3.04–3.11 Ma), C2An.2n subchron
(3.11–3.22 Ma), Mammoth subchron (3.22–3.30 Ma)
and the upper part of C2An.3n subchron (top at 3.33
Ma). The bottom owstone layer at the NW side of the
studied prole terminates at about 3.4 Ma. For the
conclusion it may be emphasised that the roughly
3 m high prole was growing for more than 3 Ma
and that new speleothems on top are still growing.
Palaeomagnetic research on karst sediments in Slovenia
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
54
material is derived from a single source, Eocene
siliciclastics of the Pivka Basin (Zupan Hajna, 1998).
Detailed palaeomagnetic and magnetostratigraphy
data (Zupan Hajna et al., 2008a, b) revealed greater
complexity than previous magnetostratigraphic
interpretations (Šebela & Sasowsky, 1999). Three
short R magnetozones (excursions) were detected
only in a few places (Spodnji Tartarus). Within the
limits of statistical error, the Spodnji Tartarus North,
Pisani rov and Biospeleološka postaja proles show
declination and inclination directions close to the
present. The Rudolfov rov, Spodnji Tartarus South,
Umetni tunel 1, Male jame and Zguba jama proles
must be older due to slight or distinct counter-
clockwise rotation associated with tectonism of
the Adria Microplate (Vrabec & Fodor, 2006). We
interpreted most of the sediments as being younger
than 0.78 Ma, belonging to various depositional
events within the Brunhes Chron. The N polarization
in sediments of the Umetni tunnel 1 site and Zguba
jama can be linked with some of N polarized subchrons
older than 0.78 Ma. Sediments in Umetni tunnel 1
(Fig. 2A) are the oldest in the system and were not
included in older stratigraphic schemes (Gospodarič,
1976, 1981, 1988). They may be correlated with
Olduvai, Reunion or even older chrons (i.e. from 1.77
to over 2.15 Ma). The cave system has evolved over
a long period of time, governed by the functioning
of Planinsko polje in relation to the evolution of the
resurgence area in Ljubljana Moor further to the E.
General stabilization of the hydrological system with
low hydraulic head led to the evolution of caves in
Račiška pečina, Ulica pečina and the unroofed Ulica
Cave represent most likely remnants of the same cave
system, which was developed at the same time and at
the same altitude. The cave system still retains traces
of paragenetic, epiphreatic and phreatic features (large
cupolas and scallops). The transition to the vadose
zone caused exhumation and internal redistribution of
cave ll and the growth of massive speleothems (large
domes and stalagmites) on allogenic deposits. The
system was later dissected by erosion and denudation
into the segments with more entrances, where the
cave roof was thinned or completely destroyed.
Notranjski kras
The karst of Notranjska (Inner Carniola) includes
a large proportion of the central and highest parts
of the Dinaric Karst, with varying geomorphic units
(high-karst plateaus, planated surfaces at lower
positions, small ysch basins with sinking rivers,
and karst poljes). Several sites were studied in the
area surrounding Postojna: Postojna cave system (8
proles; Fig. 6), Zguba jama (2 proles), Planinska
jama (1 prole), Markov spodmol (2 proles) and
Križna jama (2 proles).
The Postojnska jama–Planinska jama cave system
and a number of smaller adjacent caves (such as
Zguba jama) are developed in the karst between
Postojna Basin and Planinsko polje. The caves are
located between two dextral strike-slip fault zones
of the Dinaric direction. Caves contain lithologically
diverse sedimentary ll, ranging from speleothems
to allogenic uvial sediments. The allogenic clastic
Fig. 5. Photograph of NW part of Račiška pečina prole with visible trenches, where owstone was sampled.
Nadja Zupan Hajna, Andrej Mihevc, Petr Pruner, Pavel Bosák
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
55
Fig. 6. Prole locations in Postojnska jama Cave system (cave map after Cave Register of the IZRK ZRC SAZU and JZS ). Legend: 1 – proles in
Spodnji Tartarus, 2 –Umetni tunnel I prole, 3 – Umetni tunnel II prole, 4 – prole in Biospeleološka postaja, 5 –Male jame prole, 6 – Stara jama
prole, 7 – Pisani rov prole.
Palaeomagnetic research on karst sediments in Slovenia
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
56
epiphreatic and paragenetic conditions over a long
time-span. Individual cave segments or passages were
completely lled and exhumed several times during
the evolution of the cave (Zupan Hajna et al., 2008a).
Erosion and deposition were synchronous in different
parts of the system. Alternation of depositional and
erosional phases may be connected with changing
conditions within the cave system, the functioning
of the resurgence area, collapse, climatic change,
tectonic movement and the intrinsic mechanisms of
contact karst.
Markov spodmol is a horizontal cave about 900
m long and 12 m deep. The entrance lies on the
southern edge of a blind valley opening into the Pivka
Basin. The cave serves as an intermittent ponor for
the small brook. The studied prole was situated in
a side passage or large niche of the main passage
about 150 m from the entrance. The section of uvial
sediments is about 4 m thick. The palaeomagnetic
and magnetostratigraphy results we obtained showed
that the prole in Markov spodmol is composed at
least of three different sequences (Zupan Hajna et al.,
2008a). The age of the ll can be interpreted as follows:
the upper laminated clay was deposited within the
normal Brunhes Chron, the multi-coloured clays and
sands/gravels were deposited in Matuyama or Gauss
Chrons, and the lower laminated clay is older than
the middle sequence. Traces of in situ weathering in
the lower part of the prole indicate a quite prolonged
hiatus in deposition. The creation of a weathered zone
under subsurface conditions needs prolonged time
and warm/humid external climate. The weathering
supports a rather higher age of the prole.
Križna jama is large river cave situated in the area
between Loško, Bloško and Cerkniško poljes. Remains
of uvial sediments are preserved throughout the
entire cave, indicating that it was lled by more and
different sediments in the past (Gospodarič, 1974).
The Medvedji rov (Bear Passage) represents one of
older passages. There were studied 2 proles where
the remains of Ursus spelaeus in clay are inter-bedded
among owstone sheets. New radiometric dates
(Zupan Hajna et al., 2008a) have proved the results
and interpretations of Ford & Gospodarič (1989).
Remains of cave bears in two layers are denitely
older than 125 ka. Paleomagnetic results (prevailing
N polarization of the proles) indicate an age younger
than the Brunhes/Matuyama boundary at 780 ka.
The thin R polarized magnetozone represents one of
the short-lived excursions of the magnetic eld within
the Brunhes Chron, which is older than about 146–
160 ka.
Dolenjski kras
The karst of Dolenjska (Lower Carniola) is an area of
the SE of Slovenia; it is also described as the covered
lowland karst of Dolenjska (Gams, 2003; Kranjc,
1990) and belongs to the Dinaric Karst. Dolines,
uvalas, karst poljes and rounded hills predominate.
The surface is covered with a thick layer of red karst
soil. A sediment prole was taken at Prole No. 207 of
highway construction in the section Hrastje–Lešnica,
N of Novo mesto (Zupan Hajna et al. 2008a).
Hrastje prole was composed mostly of clays and
silty clays with interbeds to laminas of clayey-sandy
and clayey silts. The colour of the sediments was
dominantly grey, sometimes brown and beige mottled
and with yellowish brown lamination. The whole
prole is N polarized except the lowest sample, which
is R (Zupan Hajna et al., 2008a). Without gastropod
and plant determinations, there can be three
possible interpretations of the age: the deposition
took place within the Brunhes Chron (<780 ka), or
at the Brunhes/Matuyama boundary (780 ka). The
R polarization represents an excursion within the N
polarized magnetozone; or the prole could be older
than the Brunhes Chron.
Alpine Karst
The Alps in the northern part of Slovenia form two
large mountain groups: the Julian and Kamnik–
Savinja Alps with dominant W–E orientation. The
Julian Alps are deeply incised by the Soča and Sava
river valleys and their tributaries. The plateaus and
other surfaces are without surface waters. Karst
springs appear in the bottoms of the valleys. There
are numerous closed depressions, dolines and deep
vadose shafts, but horizontal caves are rare (e.g., Jama
pod Babjim zobom, Spodmol nad Planino Jezero).
The high plateaus and valleys were glaciated during
the Pleistocene. Glaciation only slightly transformed
the pre-glacial karst landscape. The Kamnik–Savinja
Alps are dissected by the Sava and Savinja rivers into
narrow ridges and valleys. Numerous karst plateaus
are found on the SE. Remnants of several horizontal
caves are preserved, but deep shafts predominate.
Fluvial sediments can be found in some horizontal
caves, e.g., Potočka zijalka and Snežna jama na Raduhi
(Mihevc, 2001b). These sediments were deposited by
sinking rivers before the main valley entrenchment
that followed the fast tectonic uplift of this part of Alps
(Bosák et al., 2002).
The substantial age of cave lls in the area can be
deduced from occurrences of cave entrances on upper
slopes of deeply entrenched valleys at high altitudes:
e.g., Jama pod Babjim zobom, Spodmol nad Planino
Jezero and Snežna jama (Zupan Hajna et al., 2008a).
The ll of caves is clearly older than 1.77 Ma. Such an
old age indicates the entrenchment of rivers for more
than 900 m which was the consequence of the tectonic
uplift (Mihevc, 2001b). The change of depositional
environment is well reected by the palaeomagnetic
parameters (Zupan Hajna et al., 2008a).
Speleothems in Snežna jama (Fig. 7) can be correlated
with the Matuyama to Gilbert Chrons. The geometry
and arrangement of individual magnetozones, taking
into account also hidden time on unconformities,
indicates that the most probable correlation with the
GPTS offer subchrons at 3.0 to 5.0 Ma time span;
another acceptable correlation could be 1.8 to 3.6 Ma
(Bosák et al., 2002).
The evolution of karst plateaus and massifs in the
Slovenian Alps is comparable with another part of the
Alpine chain – the Northern Calcareous Alps – where
Nadja Zupan Hajna, Andrej Mihevc, Petr Pruner, Pavel Bosák
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
57
Fig. 7. Basic magnetic and palaeomagnetic properties of Snežna jama. Legend: Lithology: waves – owstone; Polarity scale: black – normal
polarized magnetozones, white – reverse polarized magnetozones, grey – mixed polarity; MS – magnetic susceptibility; NRM – natural remanent
magnetization; D – declination; I – inclination.
Palaeomagnetic research on karst sediments in Slovenia
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
58
caves occur also from 1300 to more than 1700 m
a. s. l. (Zötl, 1989; Frisch et al., 2000), i.e. about 900
m above recent river-beds.
Isolated Karst
Small karst plateaus, ridges, dolines, blind valleys
and caves are interspersed with uvial landforms
formed on non-carbonate rocks are characteristic
for the Isolated Karst of the middle part of Slovenia.
There are several small rivers sinking into the karst
and then emerging on the other sides of ridges.
Tajna jama is situated in a small isolated karst area
in the central part of Slovenia. An approximately 2
m high prole (Fig. 2E) of ne laminated sediments
covered by disintegrated conglomerate is preserved
in the upper part of the meandering canyon. An
alternation of N and R magnetized zones was discovered
(Zupan Hajna et al., 2008a). The most probable age
interpretation dates back cave sediments to about
3.0 to 3.4 Ma, i.e. to the Gauss Chron. The erosion
surface within the lower R magnetized zone is related
also with the change of inclination. The boundary, if
representing a prominent hiatus, could shift the age
of the lower R/N boundary down to 4.18 Ma (top of the
Cochiti subchron). This interpretation is supported by
declination values.
CONCLUSIONS
Paleomagnetic research on cave lls in the
Dinaric, Alpine and Isolated karsts has opened new
horizons for the interpretation of karst and cave
evolution. The data inform us that a number of common
features and evolution trends exist in all studied
regions. On the other hand, as the consequence of
different post-Eocene tectonic regimes, there exist
distinct differences in evolution of smaller geomorphic
units within the more extensive ones.
The most important result concerns the age (Tab.
1 and 2) of cave lls, which are substantially older
than expected from earlier research. Palaeomagnetic
Tab. 1. Ages of cave sediments interpreted from Dinaric Karst (bold numbers = Th/U data).
Name of site Name of prole Age (Ma) Age of cave ll
Min. Max.
Grofova jama ? Up to 35
Miocene/Pliocene
Črnotiče I 4.2 5.4
Briščiki >1.77 >5.0
Jama pod Kalom Lower part >1.77 >5.0
Divača prole >1.77 >5.23
Kozina prole >1.77 >5.0
Trhlovca >1.77 >5.0
Divaška jama Lower part >1.2 >5.0
Črnotiče II Right 1.77? <3.58
Pliocene
to
Pleistocene (Günz/Mindel)
Črnotiče II Main 1.8 3.58
Račiška pečina 1.77 >3.4
Markov spodmol I <0.78 3.58
Markov spodmol II >0.78 3.58
Postojnska jama Umetni tunel I <0.99 >2.15
Postojnska jama Male jame ? >0.78
Postojnska jama White sandstone ? >0.78
Zguba jama I+II <0.78 >0.78
Divaška jama Upper part 0.092 0.576
Pleistocene (Mindel)/Holocene
Jama pod Kalom Upper part <0.05 <0.78
Postojnska jama Tartarus North ? <0.78
Postojnska jama Tartarus South >0.122 <0.78
Postojnska jama Pisani rov >0.35 <0.78
Postojnska jama Stara jama ? <0.78
Planinska jama Rudolfov rov ? <0.78
Račiška pečina Top <0.09 <0.78
Križna jama I+II ≥0.03 <0.78
Pečina v Borštu >0.194 <0.78
Tab. 2. Ages of cave sediments interpreted from Alpine and Isolated karsts (bold number = Th/U data).
Name of site Age (Ma) Age of cave ll
Min. Max.
Snežna jama >1.2 >5.0
Miocene/Pleistocene
Tajna jama ±0.78 4.18
Jama pod Babjim zobom >0.78 >1.77
Spodmol nad Planino Jezero >0.78 ?
Nadja Zupan Hajna, Andrej Mihevc, Petr Pruner, Pavel Bosák
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
59
data in combination with other dating methods has
shifted the possible beginning of speleogenesis and
cave inlling processes deeply below the Tertiary/
Quaternary boundary.
For the rst time in Slovenia, biostratigraphic data
contributed (Horáček et al., 2007) to the correlation
of magnetostratigraphy logs with the GPTS and to
allocate the ages of cave ll more precisely to pre-
Quaternary times. Palaeontological nds in the
Račiška pečina and Črnotiče Quarry partly support
the age interpreted from magnetostratigraphy cave
lls are often Pliocene in age and even older (Horáček
et al., 2007).
The present situation in the Slovenian karst is
the result of more or less steady state karstication
since the (late) Oligocene. Nevertheless, this
ongoing period can be subdivided into individual,
but not clearly delimited, phases related to
Cenozoic palaeogeographical changes, i.e. changing
tectonic regimes, individual marine ingressions
and regressions, cessation of deposition in the
Paratethys area, evolution of tectonic basins. The
period contains three distinct phases of massive
deposition in caves with extant sediments dated
to about 5.4–4.1 Ma (Miocene–Pliocene), 3.6–1.8
Ma (Pliocene), and Quaternary, following the
cessation of Miocene deposition in Slovene part of
the Pannonian Basin, and the last, but principal,
change of the tectonic regime at about 6 Ma (Vrabec
& Fodor, 2006).
ACKNOWLEDGMENTS
We acknowledge eld assistance of the technical
staff of the Karst Research Institute ZRC SAZU from
Postojna and Institute of Geology AS CR, v. v. i. from
Prague. Analyses, processing and interpretation in the
Czech Republic were carried out within projects No.
AV0Z30130516, IAA300130701 and MEB 090619.
Research activities in Slovenia were covered by
research programs of the Slovenian Research Agency
Nos. P6–0119–0618 and P0–0119, and project No.
J6–6345–0618–04.
REFERENCES
Audra P., 2000 Le karst haut alpin du Kanin (Alpes
juliennes, Slovénie-Italie). Etat des connaissances
et données récentes sur le fonctionement actuel et
l´évolution plio-quaternaire des structures karstiques.
Karstologia, 35: 27-38.
Bosák P., Hercman H., Mihevc A. & Pruner P., 2002
High resolution magnetostratigraphy of speleothems
from Snežna Jama, Kamniške–Savinja Alps, Slovenia.
Acta carsologica, 31/3: 15-32.
Bosák P., Knez M., Otrubová D., Pruner P., Slabe T. &
Venhodová D., 2000 – Palaeomagnetic Research of
Fossil Cave in the Highway Construction at Kozina, SW
Slovenia. Acta carsologica, 29/2: 15-33.
Bosák P., Mihevc A. & Pruner P., 2004 Geomorphological
evolution of the Podgorski Karst, SW Slovenia:
Contribution of magnetostratigraphic research of the
Črnotiče II site with Marifugia sp. Acta carsologica,
33/1: 175-204.
Bosák P., Mihevc A., Pruner P., Melka K., Venhodová D.
& Langrová A., 1999 – Cave ll in the Črnotiče Quarry,
SW Slovenia: Palaeomagnetic, mineralogical and
geochemical study. Acta carsologica, 28/2: 15-39.
Bosák P., Pruner P. & Kadlec J., 2003
Magnetostratigraphy of cave sediments: Application
and limits. Studia Geophysica et Geodaetica, 47, 2:
301-330.
Bosák P., Pruner P. & Zupan Hajna N., 1998
Paleomagnetic research of cave sediments in SW
Slovenia. Acta carsologica, 27/2: 151-179.
Bosák P., Pruner P., Mihevc A. & Zupan Hajna N., 2000
Magnetostratigraphy and unconformities in cave
sediments: case study from the Classical Karst, SW
Slovenia. Geologos, 5: 13-30.
Brodar S., 1966 – Pleistocenski sedimenti in palaeolitska
najdišča v Postojnski jami (Pleistocene sediments of
Palaeolitic site in Postojna Cave). Acta carsologica,
4: 57-138.
Buser S., 1989 Geološki razvoj Slovenije. In: Javornik
M., Voglar D. & Dermastia A. (Eds.): Enciklopedija
Slovenije. 1. Mladinska knjiga, 1987-2002, 1989, 3,
Eg-Hab.: 195-203.
Cande, S.C. & Kent, D.V., 1995 Revised calibration
of the geomagnetic polarity timescale for the Late
Cretaceous and Cenozoic. Journal of Geophysical
Research, 100/B4: 6093-6095.
Ford D. & Williams P., 2007 Karst Hydrogeology and
Geomorphology. Wiley, Chichester, 562 p.
Ford D.C. & Gospodarič R., 1989 U series dating studies
of Ursus spelaeus deposits in Križna jama, Slovenia.
Acta carsologica, 18: 39-51.
Franke H. & Geyh M., 1971 14C - Datierungen von
Kalksinter aus slowenischen Höhlen. Der Aufschluss,
22: 235-237.
Frisch W., Székely B., Kuhlemann J. & Dunkl I., 2000 –
Geomorphologica evolution of the Eastern Alps in response
to Miocene tectonics. Zeitschrift für Geomorphologie,
44: 103-138.
Gams I., 2003: Kras v Sloveniji v prostoru in času. Založba
ZRC, ZRC SAZU, Ljubljana, 516 p.
Gospodarič R., 1974 Fluvialni sedimenti v Križni jami
(Fluvial sediments in Križna Cave). Acta carsologica, 6:
327-366.
Gospodarič R., 1976 – Razvoj jam med Pivško kotlino
in Planinskim poljem v kvartarju (Evolution of caves
between Pivka Basin and Planina Polje in Quaternary).
Acta carsologica, 7: 5-139.
Gospodarič R., 1981 – Generations of speleothems in the
Classical Karst of Slovenia. Acta carsologica, 9 (1980):
90-110.
Gospodarič R., 1988 Paleoclimatic record of cave
sediments from Postojna karst. Annales de la Société
Géologique de Belgique, 111: 91-95.
Horáček I., Mihevc A., Zupan Hajna N., Pruner P. &
Bosák P., 2007 – Fossil vertebrates and paleomagnetism
update one of the earlier stages of cave evolution in the
Classical Karst, Slovenia: Pliocene of Črnotiče II site and
Račiška pečina. Acta carsologica, 37/3: 451-466.
Ikeya M., Miki T. & Gospodarič R., 1983 ESR
Dating of Postojna Cave Stalactite. Acta carsologica,
11(1982): 117-130.
Palaeomagnetic research on karst sediments in Slovenia
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
60
Kranjc A., 1990 Dolenjski kraški svet (The Karst World
of Dolenjska). Dolenjska založba, Novo mesto, 240 p.
Mihevc A. & Lauritzen S.E., 1997 Absolute datations
of speleothems and its speleomorphological signicance
from Divaška jama and Jazbina caves; Kras plateau,
Slovenia. Proc. 12th International Congress of
Speleology, vol. 1, La Chaux-de-Fonds, Switzerland:
57-59.
Mihevc A. & Zupan Hajna N., 1996 – Clastic sediments
from dolines and caves found during the construction of
the motorway near Divača, on the classical Karst. Acta
carsologica, 25: 169-191.
Mihevc A., 1996 – Brezstropa jama pri Povirju (Unroofed
cave at Povir). Naše jame, 38: 92-101.
Mihevc A., 2001a Speleogeneza Divaškega krasa
(Speleogenesis of the Divača Karst). Zbirka ZRC, 27,
Ljubljana, 180 p.
Mihevc A., 2001b – Jamski uvialni sedimenti v Snežni
jami na Raduhi in v Potočki zijalki (Cave uvial
sediments in Snežna jama na Raduhi and Potočka
zijalka). Geološki zbornik, 16: 60-63, Ljubljana.
Mihevc A., Bosák P., Pruner P. & Vokal B., 2002 – Fossil
remains of the cave animal Marifugia cavatica in the
unroofed cave in the Črnotiče quarry, W Slovenia.
Geologija, 45/2: 471-474.
Pirc S., 2007 Short otline of geology of Slovenia. In:
Hlad B. & Herlec U. (Eds.): Geological heritage in the
South-European Europe. Field Guide, Environmental
Agency of the Republic of Slovenia, Ljubljana: 5-6.
Placer L., 1999 Contribution to the macrotectonic
subdivision of the border region between Southern Alps
and External Dinarides. Geologija, 41(1998): 223-255.
Placer L., 2007 Kraški rob (landscape term); Geologic
section along the motorway Kozina -Koper (Capodistria).
Geologija, 50/1: 29-44.
Sasowsky I., 2007 Clastic Sediments in Caves – Imperfect
Recorders of Processes in Karst. Acta carsologica, 36/1:
143-149.
Šebela S. & Sasowsky I., 1999 Age and magnetism of
cave sediments from Postojnska jama cave system and
Planinska jama Cave, Slovenia. Acta carsologica, 28/2:
293-305¨
Šebela S. & Sasowsky I., 2000 Paleomagnetic dating
of sediments in caves opened during highway
construction near Kozina, Slovenia. Acta carsologica,
29/2: 303-312.
Vrabec M. & Fodor L., 2006 – Late Cenozoic tectonics of
Slovenia: structural styles at the Northeastern corner
of the Adriatic microplate. In: Pinter N., Grenerczy
G., Weber J., Stein S. & Medak D. (Eds.), The Adria
microplate: GPS geodesy, tectonics and hazards, NATO
Science Series, IV, Earth and Environmental Sciences,
61, Springer, Dordrecht: 151-168.
Zötl J., 1989 – Paleokarst as an important hydrogeological
factor. In: Bosák P., Ford D.C., Głazek J. & Horáček
I. (Eds), Paleokarst. A systematic and regional review,
Academia–Elsevier, Praha–Amsterdam: 483-509.
Zupan Hajna N., 1996 The valuation of absolute
speleothem dating from Slovenia. In: Lauritzen, S.-
E. (Ed.), Climate change: the Karst record: extended
abstracts of a conference held at Department of geology
University of Bergen, Norway, Charles Town: Karst
Waters Institute, Special Publication, 2: 185-188.
Zupan Hajna N., 1998 Mineral composition of clastic
cave sediments and determination of their origin. Kras i
speleologia, 9(XVIII): 169-178.
Zupan Hajna, N., Mihevc A., Pruner P. & Bosák P., 2008a
Palaeomagnetism and Magnetostratigraphy of Karst
Sediments in Slovenia. Carsologica, 8, Založba ZRC,
Ljubljana, 266 p.
Zupan Hajna, N., Mihevc A., Pruner P. & Bosák P., 2008b
Cave sediments from the Postojnska-Planinska cave
system (Slovenia): evidence of multiphase evolution in
epiphreatic zone. Acta carsologica, 37/1: 63-86.
Zupan N., 1991 Flowstone datations in Slovenia. Acta
carsologica, 20: 187-204.
Nadja Zupan Hajna, Andrej Mihevc, Petr Pruner, Pavel Bosák
International Journal of Speleology, 39(2), 47-60. Bologna (Italy). July 2010
... In sediments from caves close to the surface and from unroofed caves sediments, no minerals indicating loess origin were found (e.g. amphiboles which are typical of loess sediments in Istria; Durn 2003), thus eolian origins can be excluded; even some of them from unroofed caves there were dated to 5-4 Ma (Zupan Hajna et al. 2008a, 2010. Some of the red coloured sediments and red soil passed through weathering in a period of tropical climate what is indicated by presence of bauxite minerals; examples are red clasts from cave sediments in Trhlovca Cave ( Fig. 4.5). ...
... Although we worked with all the types of facies listed during the exploration of sediments in Slovenian caves, slackwater and channel facies were the most represented and dated in our studied cases (e.g. Zupan Hajna et al. 2008a, 2010. Due to the dynamic environment of cave interiors and periodicity of events, sedimentary sequences often represent a series of depositional and erosional events (sedimentary cycles); they are separated by unconformities in which substantial time spans can be hidden (e.g. ...
... Fossil remnants of invertebrates, some of them most likely cave animals, were found in clay layers in the caves Trhlovca and Račiška pečina (Moldovan et al. 2011). Their age was defined by position in the sediment profile position by palaeomagnetic dating to Pre-Qaternary (Zupan Hajna et al. 2010). ...
Chapter
About 44% of Slovenia’s surface consists of carbonate rocks. Karst geomorphology and over 13,000 known caves represent a significant proportion of its landscape. Various sediments present on the karst surface in the form of clastic or precipitated deposits can cover or fill smaller or extended areas and they can also accumulate in the caves.
... They also contain well-developed and time-limited normal-polarised Olduvai Subchron ages (1.95-1.77 Ma) (Zupan Hajna et al., 2008Hajna et al., , 2010Hajna et al., , 2020. The Pleistocene and Pliocene ages of the Račiška Pečina profile are interesting because of the climatic and paleogeographic changes that occurred on Earth's surface during these periods (Zacwijn, 1974;Van Couvering, 1996;Lourens et al., 2004). ...
Article
Full-text available
Establishing a chronology of events is a critical step in reconstructing the palaeoclimate and it is important for all types of environmental records, including speleothems. Here, we analysed a unique series of flowstones deposited between 3.2 Ma (marine isotope stage (MIS) Km3) and 0.08 Ma (MIS 5). The studied flowstones are located in a classic karstic environment, the Račiška Pečina Cave in south-western Slovenia. Further, a detailed chronology of events was constructed based on oxygen isotope stratigraphy (OIS), combined with magnetostratigraphy and U-series dating. Two curves were selected as reference records where the LR04 record was used as the global curve and a Mediterranean record was used as the regional curve. The Račiška Pečina profile was divided into two segments separated by a principal disconformity. The lower segment correlated better with the regional Mediterranean curve, while the upper segment was with the global LR04 curve. These findings suggest that the main factors controlling environmental conditions in the cave area changed between 3.2 and 0.8 million years ago.
... Kean et al., 1997;Carrancho et al., 2012;Herrej on et al., 2019) and dating clastic cave sediments using magnetostratigraphic correlation (e.g. Pospelova et al., 2007;Hajna et al., 2010;Pruner et al., 2010;Herries and Shaw, 2011;Bos ak and Pruner, 2011;H€ auselmann et al., 2015;Bella et al., 2019). At the Atapuerca archeological site, Carracedo et al. (1987), Par es and P erez-Gonz alez (1999) and Par es et al. (2000,2006) reported crucial magnetostratigraphic results for the Gran Dolina, Sima de los Huesos, and Sima del Elefante caves (cf. ...
Article
The Galería Complex is a cave sediment succession at the Atapuerca paleoanthropological site (Burgos, Spain) that offers detailed environmental information about the late Middle Pleistocene, especially the period between marine oxygen isotope stages MIS10 and MIS7. Previous studies have reconstructed the chronology and detailed the environmental development of this key succession. We introduce rock magnetic climate proxies from the sedimentary units of the Galería succession that we correlate with the global climate record as represented by the marine oxygen isotope record. The cave sediment sequence consists of five infilling phases, four of which were sampled at high resolution across a 5 m thick composite profile. We propose a novel goethite climate proxy along with a frequently used ultrafine ferrimagnetic mineral proxy for paleoclimate reconstruction and detailed chronostratigraphic correlation with isotope stages and substages MIS10/MIS10-9, MIS9e-a and MIS8. The proxies reveal new paleoenvironmental information about paleoprecipitation and indicate that MIS9e was a humid (~650 mm/ year maximum annual precipitation) and intense interglacial in northern Spain that declined in steps into the globally weak glacial stage MIS8. MIS8 consisted of drier periods with 430e510 mm/year annual precipitation and at least one humid substage (600 mm/year).
... 9) and from some caves only their insoluble clastic sediments remain on the karst surface; from denudation rates was also calculated that unroofed caves are older than 5 Ma. The paleomagnetic and magnetostratigraphic research of karst sediments in Slovenia (e.g., Zupan Hajna et al., 2008, 2010 has been carried out since 1997. The results were in some sites calibrated by U-series, paleontological and geomorphological dating and gave the ages of the cave sediments from recent to over 5 Ma. ...
Chapter
The Dinaric karst is geographically and geologically the carbonate part of the Dinaric Mountains on the Balkan Peninsula between the Adriatic Sea and the Pannonian Basin. The Dinaric karst is “classical” karst because of many reasons: the term karst (kras) was derived from its NW part (Kras plateau); from the region originate such international terms as polje, uvala, doline, kamenitza, and ponor and it is also the landscape where karstology and speleology as sciences were born. The most characteristic relief forms are high karst plateaus and numerous poljes elongated in NW-SE direction (“Dinaric” direction), leveled surfaces, dolines, large and deep caves, sinking rivers and abundant springs. According to different geological, hydrological, climate and geomorphic characteristics the Dinaric karst can be divided into three belts parallel to the Adriatic Sea: low coastal Adriatic karst, high mountain karst and low continental inland karst. The Dinaric karst is known also as a limestone desert, a bare rocky landscape that results from climate conditions and especially because of intense land use in past centuries.
... The presence of magnetically reversed sediments therefore indicates a minimum age for cave alluviation of 0.78 Ma. With a stacked series of normal and reversed-polarity sediments, this method can be used to date caves back several million years (Farrant et al., 1995;Stock et al., 2005;Hajna et al., 2010;Rossi et al., 2016;Bella et al., 2019). As a dating tool, palaeomagnetism suffers from two main limitations: first, it requires suitable fine-grained sediments within the cave; second, it is a correlative tool that cannot yield absolute ages for stratigraphic units except when magnetic reversals are identified and reliably correlated with the global record. ...
Article
Full-text available
Quantifying rates of river incision and continental uplift over Quaternary timescales offer the potential for modelling landscape change due to tectonic and climatic forcing. In many areas, river terraces form datable archives that help constrain the timing and rate of valley incision. However, old river terraces, with high‐level deposits are prone to weathering, and often lack datable material. Where valleys are incised through karst areas, caves and sediments can be used to reconstruct the landscape evolution because they can record the elevation of paleo‐water tables, and contain preserved datable material. In Normandy (N. France), the River Seine is entrenched into an extensive karstic Chalk plateau. Previous estimates of valley incision were hampered by the lack of preserved datable fluvial terraces. A stack of abandoned phreatic cave passages preserved in the sides of the Seine valley can be used to reconstruct the landscape evolution of the region. Combining geomorphological observations, paleomagnetic and U/Th dating of speleothem and sediments in eight caves along the Lower Seine valley, we have constructed a new age model for cave development and valley incision. Six identified cave levels up to ~100 m asl were formed during the last ~1 Ma, coeval with the incision of the River Seine. Passage morphologies indicate that the caves formed in a shallow phreatic/epiphreatic setting, and modified by sediment influxes. The valley's maximum age is constrained by the occurrence of late Pliocene marine sand. Paleomagnetic dating of cave infills indicate that the highest‐level caves were being infilled prior to 1.1 Ma. The evidence from the studied caves complemented by fluvial terrace sequences indicate rapid river incision occurred during Marine Isotope Stage (MIS) 28 to 20 (0.8‐1 Ma), with maximal rates of ~0.30 m ka‐1, dropping to ~0.08 m ka‐1 between MIS 20‐11 (0.8‐0.4 Ma), and 0.05 m ka‐1 from MIS 5 to the present‐time.
... Demagnetization was performed with an applied alternative field up to 150 mT using a 2G760 cryogenic magnetometer, equipped with the 2G600 degaussing system controller. Before this analysis, each sample remained at least 48 h in a null magnetic field, preventing a possible low-coercivity viscosity overprinting the detrital remanent magnetization (DRM) (Hill, 1999;Stock et al., 2005;Hajna et al., 2010). If the hypothesis of instantaneously locked-in DRM seems reasonable compared with the studied time span, it is important to keep in mind that the details of DRM processes (as for instance the locked in time) are not well understood (Tauxe et al., 2006;Spassov and Valet, 2012) and could possibly lead to small variations (few percents) in the following computed incision rates. ...
Article
Full-text available
The evolution of intraplate orogens is still poorly understood. Yet, it is of major importance for understanding the Earth and plate dynamics, as well as the link between surface and deep geodynamic processes. The French Massif Central is an intraplate orogen with a mean elevation of 1000 m, with the highest peak elevations ranging from 1500 to 1885 m. However, active deformation of the region is still debated due to scarce evidence either from geomorphological or geodetic and seismologic data. We focus our study on the southern part of the Massif Central, known as the Cévennes and Grands Causses, which is a key area to study the relationship between the recent geological deformation and landscape evolution. This can be done through the study of numerous karst systems with trapped sediments combined with the analysis of a high-resolution digital elevation model (DEM). Using the ability of karst to durably record morphological evolution, we first quantify the incision rates. We then investigate tilting of geomorphological benchmarks by means of a high-resolution DEM. We finally use the newly quantified incision rates to constrain numerical models and compare the results with the geomorphometric study. We show that absolute burial age (10Be∕26Al on quartz cobbles) and the paleomagnetic analysis of karstic clay deposits for multiple cave system over a large elevation range correlate consistently. This correlation indicates a regional incision rate of 83 +17/-5 m Ma−1 during the last ca. 4 Myr (Pliocene–Quaternary). Moreover, we point out through the analysis of 55 morphological benchmarks that the studied region has undergone a regional southward tilting. This tilting is expected as being due to a differential vertical motion between the northern and southern part of the studied area. Numerical models show that erosion-induced isostatic rebound can explain up to two-thirds of the regional uplift deduced from the geochronological results and are consistent with the southward tilting derived from morphological analysis. We presume that the remaining unexplained uplift is related to dynamic topography or thermal isostasy due to the Massif Central Pliocene–Quaternary magmatism. Integrating both geochronology and morphometrical results into lithospheric-scale numerical models allows a better understanding of this intraplate–orogen evolution and dynamic. We assume that the main conclusions are true to the general case of intraplate deformation. That is to say, once the topography has been generated by a triggering process, rock uplift is then enhanced by erosion and isostatic adjustment leading to a significant accumulation of mainly vertical deformation.
Chapter
In this chapter, the authors deal with the physical, organic, and chemical deposits found in the dark or semi‐dark areas of caves, excluding those found in cave entrances or rock shelters. Clastic sediments in caves, excluding those found at entrances, have been the subject of numerous studies, mainly during the last 60 years. Phosphorite is a chemical deposit that can be deposited in caves. Speleothems are secondary mineral deposits that form in caves by flowing, dripping, ponded, or seeping water and take on a typical shape. They are mostly composed of minerals such as calcite, aragonite, or gypsum, but other minerals can also form entirely or partially speleothems. Speleothem texture and fabrics are increasingly used to support the interpretation of the geochemical signals (stable isotopes and trace elements) in the paleo‐environmental and paleoclimatic reconstructions based on speleothem archives.
Conference Paper
During a 21-day long cruise onboard the RV Poseidon in the year 2017., a multinational team of scientists collected water and sediment samples in the Adriatic Sea. The cruise POS514 entitled „Micropaleontology, Actuopaleontology, and Environmental Baseline Study of the Holocene to latest Pleistocene in the northern and eastern Adriatic Sea basin“ comprised scientists from German, Italian, Croatian, and Austrian institutions. Scientists measured water column properties with CTD probe, collected biological samples with plankton multi net, and collected sediments with long gravity cores, short multi- cores, Van Veen grabs, Box cores, and Frahm corer on 40 sampling stations (Figure 1a). The gravity core POS514-40-11 GC was collected along the Eastern Adriatic Coast in the northern rim of the Mid Adriatic Pit (Figure 1a) at a water depth of 212.5 m b.s.l. Its total length is 690 cm. The core is of special interest due to the focus of the Croatian Science Foundation project QMAD, with extensive studies in the area of the Krka River estuary and its development towards the MAD during the Pleistocene and Holocene eustatic sea-level fluctuations. The dating of the core was established with five dates using the AMS 14C method, calibrated with the IntCal20 calibration curve in the Clam software (Blaauw, 2010). The oldest date reached 17 900 cal BP at the core depth of 628 cm. The dates were used to create the age-depth model and calculate sedimentation rates (SR) in the MAD (Figure 1b). The peaks of the measured 137Cs activity were not completely conclusive. Other methods used for the core determination include measurements of the particle size (PSA), magnetic susceptibility (MS), carbon and nitrogen (Total C, Total N, C/N ratio, Total Organic Carbon (TOC%), Total Inorganic Carbon (TIC%)), bulk density (BD) (wet and dry), mineralogical (XRD) and derived values as Mass Accumulation Rates (MAR) and Accumulation Rates of C, N, TOC%, and TIC% (Figure 1c). A distinct change in SR, BD, as well as in MAR that starts from 9 440 cal BP to 12 100 cal BP and remains high until the end of the core. Values of the TOC% show the opposite pattern. There is a sudden rise in TIC % and MS at the lower part of the core, at 15 150 cal BP, coincident with a PSA peak of sand particles (Figure 1c). In general, sediments of the whole core are dominantly silty with 20% to 30% of clay-sized particles, with two short sand intervals. The other peak of sand particles occurs at 8 800 cal BP and can also be observed in MAR and TIC%. The C/N ratio is uniform in a range of 7 to 8, with one distinct peak at 13 000 cal BP reaching 9.8. Based on XRD analyses the main difference throughout the core is the amount of two dominant minerals – quartz and calcite. Within the top 2.7 meters (9 700 cal BP) of the core, the amount of the calcite is higher than the quartz, while in the part from the third to the fifth meter (14 700 cal BP) the amount of the quartz is higher. From the fifth meter to the bottom the amount of calcite is again higher than the amount of quartz. This coincides with changes in the other parameters measured within the core (MS, TIC MAR) (Fig 1a). Collected data enabled us to define four distinct zones throughout the core (Figure 1c). The zone POS Z1 extends from the bottom of the core until 15 150 cal BP. It is followed by the POS Z2 zone with a transition to the third zone (POS Z3) at 12 090 cal BP. The youngest and the longest zone POS Z4 extends from the 9 440 cal BP to the surface. Zones Z1 and Z2 deposited in the environment proximal to the coastline, with more pronounced terrestrial and coastal influence on the sedimentation. Zone Z3 represents gradual coastal retreat further from the location due to sea-level rise, with diminishing coastal effect. The youngest zone Z1 was sedimented in the deeper water distal environment that lasts until the present. The obtained results will be extremely helpful in the interpretation of high-resolution acoustic profiling that is planned for the next project period.
Article
Full-text available
The sedimentological record in the Račiška pečina cave sediment sequence is one of the best-preserved cave records of palaeoenvironmental changes for the last 3.4 Ma. However, as it is typical for cave terrestrial records, it contains many hiatuses in sedimentation. The section study helped to change the state of knowledge and understanding of the long-lasting deposition characteristics in the caves and provided enormous data on environmental changes over time. In the sequence are by magnetostratigraphy well recorded Pliocene/Pleistocene transition at 2.59 Ma, the Matuyama/Brunhes boundary at 0.773 Ma, and the presence of Olduvai subchron between 1.78 and 1.925 Ma. Records of small mammals from the lower part of the section (a molar of Apodemus cf. atavus and dental fragments of Borsodia sp., and Pliomys sp.) suggest MN17 age, Clethrionomys cf. glareolus from the upper part suggests the Late Early or Middle Pleistocene age. Also worth mentioning are records of snail shells Aegopinella sp. and a troglobiont snail Zospeum sp. In the upper part of the section Ursus ex gr. spelaeus was confirmed in the yellow clay layer older than ∼72 ka, and soot material at the top of the section was radiocarbon dated on ∼11 ka, ∼9 ka, and ∼3 ka. A detailed chronology of the Račiška pečina section based on magnetostratigraphy and isotopic oxygen stratigraphy was created and correlated with palaeontological, U-series, and radiocarbon results. The climatic changes during the growth of the section were at about 2.6–2.5 Ma ago mostly controlled by global Atlantic Ocean factors, while about 0.78 Ma ago by regional Mediterranean Sea factors.
Article
Full-text available
We synthesize information on results and age of cave sediments from Slovenia. The studied sites were mostly from the Classical Karst which is situated in the NW part of Dinarides and some from the Slovenian Southern Alps. Protected in caves, sediments are generally well preserved and reveal an exceptionally good, multi-proxy record of surface environmental conditions at the time of their deposition. Here we describe results of the systematic acquisition of palaeomagnetic data within individual segments of studied sediment sections with special focus on relict and unroofed caves. In intervals with polarity change, the frequency of sampling was so high that almost continuous records of rockmagnetic and palaeomagnetic parameters were obtained. The construction of high-resolution magnetostratigraphic profile supported magnetostratigraphy correlations among profiles. Palaeomagnetic and magnetostratigraphy results were calibrated by relative, numerical, calibrated and correlated dating methods, where possible. Age sequences were compiled from spatially and temporally highly discontinuous sediment records covering different ages within the Cenozoic era. The robust chronology was constructed. Calibrated data contributed to the interpretation of speleogenesis, deposition mechanism in caves, and indirectly to the time of karst evolution and the succession of tectonic phases and climate changes. The research indicated that most of sediments in relict and unroofed caves are up to 5 Ma old which contrasts to the traditional concept of Pleistocene age of cave sediments and that caves themselves are not much older. Cave sediments have proven to be an important source of information on depositional style in caves which indirectly reflected the evolution of the surrounding landscape especially the evolution of catchment areas – i.e. climatic changes with flood events or/and changes of the tectonic regimes during Cenozoic.
Article
The high-alpine Kanin karst (Julian Alps, Slovenia-Italy). State of knowledge and new data on present functioning and plioquaternary evolution of the karstic structures. Kanin is a high-alpine karst located in the Italo-slovenian Julian Alps. Its surface was elaborated by the quaternary glaciers and includes some inherited discreet tertiary morphological features. Recent dye tracing has shown that the structural setting permits water infiltrated in Italian catchments to contribute to Slovene springs. Hydrodynamic and physico-chemical water analyses show extremely quick transfers of water during snow melt or heavy storms ; these create spectacular overflows, such as the Boka spring which emerges as a 100 m high waterfall. The phreatic zone, linked to the impermeable dam of the Soca valley, does not significantly slow these transfers. Nevertheless, it contributes to the occurrence of low water levels during recession periods, giving highly mineralised water after long resident periods. The presence of very deep and developed karst systems is explained by the combination of advantageous factors : thick and jointed limestone, important height gradient, and considerable precipitation. Paleomagnetic dating in one of the largest systems (Crnelsko brezno) attributes some glacial sediments to the Lower Pleistocene period. Their configuration seems to show that this karst system is pre-quaternary.
Article
The growth rate (3-4 mm/100 yr) and the age (about 190 000 yr) of the initial stalactite layers is estimated. Some physico-chemical dating problems of the results achieved from Postojna Cave are compared with those from Akyoshi Cave in Japan. The geochronological commentary ranged the stalactite growth beginning at the end of Mindel-Riss Interglacial, the upper seven sinter layers belonging to the Riss Glacial, Riss-Wurm Interglacial and Wurm Glacial.-from Bull. Sci. Sect. A Yougosl.
Article
Clastic sediments have played an important role in deciphering geologic history and processes since the inception of the discipline. Early studies of caves applied stratigraphic principles to karst deposits. The majority of cave deposits are breakdown and alluvium. The alluvial materials have been successfully investigated to determine ages of caves, landscape evolution, paleoenvironmental conditions, and paleobiota. Rapid stage changes and the possibility of pipe-full flow make cave deposits different than surface deposits. This and other factors present difficulties with interpreting the cave record, but extended preservation is afforded by the "roofing" of deposits. Dating by magnetism or isotopes has been successful in many locations. Caves can be expected to persist for 10 Ma in a single erosive cycle; most cave sediments should be no older than this.