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GEOLOGICA CARPATHICA,  48, 2, BRATISLAVA,  APRIL 1997

71–84

INDICATIONS OF THE MIDDLE JURASSIC EMERGENCE

IN THE CZORSZTYN UNIT

(PIENINY KLIPPEN BELT, WESTERN CARPATHIANS)

ROMAN AUBRECHT

Department of Geology and Paleontology, Faculty of Sciences, Comenius University, Mlynská dolina, 845 15 Bratislava, Slovak Republic

(Manuscript received June 12, 1996; accepted in revised form December 12, 1996)

Abstract: 

A breccia of rounded crinoidal limestone clasts cemented by two generations of stromatolites, then by

radiaxial cement with remaining voids filled by marine sediments i.e. crinoidal detritus, micrite with bivalve shells or
micrite with Pokornyopsis ostracods was found at Horné Sŕnie quarries near Trenčín. This breccia, which can be
assigned to the Krasín Breccia Member (Middle to Upper Jurassic of Czorsztyn Unit), bears several signs of freshwa-
ter influence. Isotopic data from the first stromatolite generation display a negative 

δ

13

C, the clasts in the breccia are

rounded and some dissolutional effects have been observed in the voids. The final filling of the cavities with crinoidal
detritus and later with filament microfacies suggests that the breccia was formed in the time of the transition between
Bathonian and Callovian. It is the first evidence of freshwater diagenesis in the Pieniny Klippen Belt.

Key words: 

Jurassic, Western Carpathians, Pieniny Klippen Belt, Czorsztyn Unit, carbonate sedimentology, diagenesis,

freshwater cements.

Introduction

There is a long-lasting search for evidence of emergence in
the area of the former Czorsztyn Ridge. It was provoked by
the fact that the foreland and basement of the Czorsztyn Unit
as well as of all the Pienidic units are still unknown. The
known Jurassic and Cretaceous sedimentary cover was de-
tached from its basement and stacked into nappe structures
during the first orogenic phase in the Late Cretaceous and
Paleocene. The basement itself has been lost (maybe sub-
ducted). Therefore any discovered signs of emergence would
shift the investigators “closer” to the unknown shoreline.
The emergence is supposed for the time of relative sea-level
drop during the Bajocian and Bathonian in this area, which is
indicated by the succession of relatively shallow-water facies
(mainly crinoidal limestones). The evidence of emergence
obtained up to now is restricted to the presence of a clastic
admixture of sandy to small pebble size (Birkenmajer 1963,
p. 37; Aubrecht 1993; Mišík & Aubrecht 1994 etc.), some
dissolutional phenomena caused probably by fresh-water
mixing in some neptunian dykes and voids (Mišík & Sýkora,
1993, p. 413) and to some eroded strata and rounded clasts in
the Krasín Breccia described by Mišík et al. 1994. This paper
deals with the first direct evidence of Middle Jurassic fresh-
water diagenesis in the Czorsztyn Unit.

During the fieldwork on the section of the Pruské Unit at

Samášky locality near Horné Sŕnie (Aubrecht & Ožvoldová
1994) a small outcrop with peculiar rocks was found in its
immediate neighbourhood following a roadcut (Fig. 1). The
rocks resemble the “evinosponge” breccias known from the
Oxfordian Vršatec Limestone of Czorsztyn Unit (Mišík
1979). However, it did not include any clasts of Oxfordian
coral limestones, but only of the crinoidal limestones and/or
so far unknown pink laminated limestone. By its character

and stratigraphic position, this breccia is more similar to the
Krasín Breccia (see Fig. 2) described by Mišík et al. (1994).
The site was largely disturbed by mining and the most inter-
esting samples occurred only in separated blocks. The brec-
cias appear to pass continuously into massive crinoidal lime-
stone penetrated by a network of radiaxial fibrous calcite
veinlets. As in situ observation was very difficult and the re-
lationship between various parts of the breccia and the above
mentioned transition were poorly observable, the major in-
formation has been obtained by laboratory investigations.

Methods of research

The samples were studied petrographically using a polariz-

ing microscope for thin-sections study and a paleontological
binocular microscope for direct study of weathered parts of
the examined samples. The cathodoluminescence (CL) ex-
aminations were made in the Geological Institute, University
of Wien (M. Wagreich). The chemical composition of calcite
samples was analysed by an electron microanalyser JXA 840
A, with wavelength dispersive spectrometers of JEOL-
KEVEX system in the CLEOM department, Faculty of Natu-
ral Sciences, Comenius University, Bratislava (J. Krištín).
The isotope analyses were made in the Czech Geological In-
stitute, Prague (J. Hladíková).

Petrographical and CL data, trace elements

The breccia is composed of clasts reaching up to several

tens of cm in size and, unlike in the typical Krasín Breccia, a
complex cement and sedimentary void filling (Fig. 3; Pl. I:
Figs. 1, 2). In following text, a detailed description of all

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72                                                                                              AUBRECHT

components will be given, based on the macro- and micro-
scopic observations under normal and polarized light, CL,
completed by some microprobe analyses.

Clasts —

1. The first generation of clasts is represented by

crinoidal limestones of subangular to rounded shape, con-
taining a more or less quartz dominated siliciclastic admix-
ture (with rare microclinic feldspars and heavy minerals i.e.
garnet, zircon and rutile). They are represented mainly by the
crinoidal biosparites to biomicrites with syntaxial calcite
overgrowths. In the parts where the micrite is present, fre-
quent teeth-like terminations of the syntaxial overgrowths
occur which indicate a prevention of crystal growth by later
input of micrite (Bathurst 1971 — p. 430 and the literature
cited therein). The inequable distribution of micrite testifies
to its local later emplacement. Besides crinoids, the frag-
ments of bryozoans, brachiopods, echinoid spines, bivalve
shells (rarely also gastropods), smooth-valved ostracods, ser-
pulids, agglutinated foraminifers, sessile (nubecularid) fora-
minifers, Lenticulina sp., Ophthalmidium sp., nodosarid for-
aminifers, are also present. The surface of skeletal fragments
is frequently micritized. All the resulting sediment is full of
inclusions which results in an unusual cloudy appearance
which has not been observed yet in other localities of crinoi-
dal limestones in the Czorsztyn Unit. Inclusions observed
under larger magnification do not appear to be formed of mi-
crite; they mostly resemble black organic matter, many of
them have a bubble-like shape hence they represent the fluid
inclusions. The possibility, that the cloudy appearance is re-
lated to the emergence, weathering and freshwater alteration

Fig. 2. 

Schematic lithostratigraphic column of the Czorsztyn Unit,

based on the latest data.

Fig. 1. 

Position of the locality examined.

(mentioned later), is not excluded. Rare small voids filled by
clear blocky calcite also occur in the crinoidal limestone
(their isotopic character has not been examined).

2. The second generation of clasts is represented by pink

laminated limestones often closely related to the previous
crinoidal ones (Pl. II: Fig. 3). Many cases of transitions be-
tween them have been identified even within a single clast
(Pl. III: Fig. 3). They are pelmicrites with laminae of crinoi-
dal detritus up to 1 cm thick. The laminae are often convex
and laterally pinching out. They are composed of the same
material as the crinoidal limestones mentioned above. The
lamination is also observable in the pelmicrites themselves
(the pelloids may be of microbial origin — see Reitner &
Neuweiler et al. 1995; Monty 1995). They resemble stroma-
tolitic structures in which the pellets were formed by the mi-
crobial calcification or they were trapped by algal (or micro-
bial) mats. The latter might also be true for the crinoidal
detritus. The described lithofacies was also unknown in the
Czorsztyn Unit so far. The absence of filamentous microfa-
cies (containing thin bivalve shells), typical for the Callovian
of the Czorsztyn Unit (sometimes already Bathonian —
M. Krobicki, pers. comm.), indicates its origin presumably
already during Bathonian time. Its character indicates slow
continual transition from crinoidal to muddy sedimentation.
In many other localities of the Czorsztyn Unit, this change in
sedimentation is abrupt with a sharp boundary in the sedi-
mentary record (frequently with Fe-Mn hardgrounds be-
tween) due to the rapid sea-level rise, after which the neritic
sedimentation followed. However, according to my opinion,
the mentioned lithofacies is not related to this process, but it

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INDICATIONS OF THE MIDDLE JURASSIC EMERGENCE                                                       73

represents sediment deposited in a special environment. As
will be mentioned later, its deposition was followed by (or
was directly related to) the emergence and repeated submer-
sion all during the continuing sedimentation of crinoidal
limestones in the basin. The most probable explanation is
that its deposition took place in the restricted sheltered near-
shore area or possibly even in a cave environment. This theo-
ry was suggested by the irregular lammination and presence
of laminae with cavity fauna in some samples (see chapter
about the signs of carstification).

Stromatolitic crusts 

are laminated clotted pelmicrites

quite similar to some of the laminated limestones mentioned
above if the crinoidal detritus is excluded. Like the previous
ones, they may represent either cyanoliths (Pl. II: Fig. 4; Pl.
III: Fig. 1) or microbialites (Pl. III: Fig. 2), since most pelloi-
dal structures resemble those defined as being of microbial
origin (Reitner & Neuweiler et al. l.c.; Monty l.c.). However,
the pelloids are not present all through the stromatolites,
hence part of them may also have been formed as a calcified
algal mat. The stromatolites with thickness reaching up to 5
cm are developed irregularly on many of the clasts. Their ab-
sence may be either primary, due to prevention of the forma-
tion by the direct contact of the clasts, or secondary, due to
their break-down by the repeated reworking of the sediment
(Pl. V: Fig. 2). Thus they frequently form a third generation

of debris in the breccia (after crinoidal and pink micritic
limestones) (Pl. III: Fig. 4). By petrographic and isotopic in-
vestigations, at least two generations of stromatolites may be
distinguished. The first appear macroscopically as pink mi-
crite with faint lamination frequently cementing several
clasts together (Pl. II: Figs. 1, 2). Such clusters frequently
bear signs of reworking after which a second generation of
stromatolites onlapped on the new clast. Unlike the older
generation of stromatolites, the second one is often macro-
scopically distinctly laminated (Pl. III: Fig. 1) with brown-
ish, yellowish and greyish colour. However, the variability in
stromatolites sometimes precludes the unequivocal identifi-
cation of their origin; hence the isotopes provide the only re-
liable source of information.

Radiaxial fibrous calcite 

(RFC) represents an almost

ubiquitous cement generation all through the breccia. Its
thickness varies from 0.7 cm to almost 2 cm. Some crusts
have no constant thickness, which could be caused by the si-
multaneous filling of the void by internal sediment (thicken-
ing upward of the crust). However, such a phenomenon is not
found very frequently. Varying thickness of the RFC crusts
also results from the filling of depressions and surface irreg-
ularities on the clasts (Pl. V: Figs. 3, 4). The density of the
RFC vein network is irregular. RFC sometimes fills straight
fractures in the limestone but more frequently surrounds the
clasts in the breccia. This cement generation overlaps almost
all clasts together with their incomplete stromatolite enve-
lopes, being itself disturbed only locally by tiny fractures (Pl.
V: Figs. 1, 2). Radiaxial cement is sometimes interlayered
with very thin stromatolitic laminae (Pl. IV: Fig. 1; Pl. V:
Figs. 1, 2). RFC most probably represents a marine precipi-
tate (see Kendall 1985) which is also supported by its bulk
isotopic values (mentioned later) which correspond to the av-
erage Jurassic marine cements (Lohmann 1988, Fig. 2.8).
However, under cathodoluminescence a relatively brightly
luminescent zone has been revealed within the RFC (Pl. IV:
Fig. 2) while all other components were non-luminescent or
very dully luminescent. This zone is similar to that described
from Carboniferous limestones in Belgium by Muchez et al.
(1991, Fig. 3C) who attributed it to a neomorphism during
later cementation. However, unlike in our luminescent zone,
there are signs of alteration also along the intercrystalline
boundaries which strongly supports the theory about later

Fig. 3. 

Schematic outline of the breccia, illustrating the relation-

ship among its various components. Explanations: — crinoidal
limestone, — laminated micritic limestone, — faintly laminat-
ed freshwater stromatolite, — distinctly laminated marine stro-
matolite, — void filling with “filamentous” microfacies, — ra-
diaxial fibrous calcite, — void filling with cavity dwelling
ostracods Pokornyopsis feifeli (Triebel), 8 - blocky calcite.

Plate I: Figs. 1, 2

— Parallel slabs from the block of breccia. c —

crinoidal limestone (clast), l — laminated stromatolitic limestone
with laminae of crinoidal detritus, s — stromatolite, r — radiaxial
fibrous calcite, c-v — crinoidal limestone (void filling), m — mi-
crite (void filling), o — void filled by ostracods Pokornyopsis feif-
eli 

(Triebel). All photos: L. Osvald.

§

Plate II:

 Figs. 1, 2 — Small clasts of crinoidal limestones coated

and partially cemented together by the freshwater stromatolites,
later by radiaxial fibrous calcite with remaining voids filled either
by sterile micrite or blocky calcite. Note that some thin layers of
RFC are interlayered within the stromatolitic coating. Thin sec-
tions. Magn. 4

×

Fig. 3 — Laminated stromatolitic limestone with

laminae of the crinoidal detritus. Thin section. Magn. 4

×

Fig. 4 

Clast of crinoidal limestone coated by asymmetrical stromatolitic
crust. Thin section. Magn. 4.5

×

.

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74                                                                                                  PLATE I

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PLATE II                                                                                                 75

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76                                                                                              AUBRECHT

neomorphism. Our sample displays only some dispersion of
the luminescence around the luminescent zone which is not
related to the intercrystalline boundaries. The microprobe in-
vestigations displayed an increased content of Mn (main ac-
tivator of the luminescence), also relatively higher Fe and
lower Mg contents if compared with the surroundings (Pl.
IV: Fig. 3). The luminescent zone was most probably precipi-
tated under reducing conditions when Mn and Fe

2+ 

were apt

to be incorporated into the calcite crystal lattice. These con-
ditions could be reached by the restricted water circulation
during cementation of the latest porosity or by the freshwater
influx and consequent alteration of the precipitating calcite.

The remaining void fillings 

are related to the size of

voids and their mutual interconnections; nevertheless, they
are also stratigraphically dependent. In some voids, a succes-
sions of several fillings were frequently observed. The fol-
lowing general succession of void filling was summarized
from the whole breccia:

1. The initial filling was separated by a thin micritic coat-

ing from its surroundings also resembling stylolite. It repre-
sents crinoidal biomicrite — packstone (Pl. V: Figs. 3, 4).
Crinoidal ossicles (also cirrals) and filaments (thin bivalve
shells) are frequent, and stromatolite fragments were also
found locally. Some occurrences of Pokornyopsis feifeli
(Triebel) which are typical for some final fillings have been
already enregistered in this zone. Besides these, some
smooth shelled ostracods are also present.

2. The sedimentation of crinoidal detritus later gave way to

micrite with a filamentous microfacies (Pl. V: Fig. 3). This
change in the microfacies observable within the cavities took
place during the Callovian in the Czorsztyn Unit (Mišík
1966; Myczynski & Wierzbowski 1994). The filamentous
microfacies consists mostly of thin bivalve shells of the ge-
nus  Bositra; also the sculptured shells of ostracods Poko-
rnyopsis feifeli

, frequent aptychi, gastropods and juvenile

ammonoids can be found among the detritus. The micritic
matrix is frequently concentrated under vaulted bivalve
shells which forms a nice “umbrella” effect (Pl. VI: Fig. 1).
This second generation of the final filling is probably already
Callovian in age. Bivalve shells are particularly overgrown
by “dog tooth” calcite, but some elongated square-terminated
crystals resembling acicular fringes of aragonite (Tucker &
Wright 1990, Fig. 7.3) may be also found (Pl. VI: Fig. 2).
However, the content of strontium, as the diagnostic trace el-
ement, is very low near the microprobe detection limit (Table
1), which makes the possibillity of aragonitic precursor un-
likely.

3. The final void filling was represented by sterile micrite

only with some thin fragments of bivalvian or ostracod shells
(filaments). When observed under CL, the micrite possess a
dull orange luminescence, which contrasts with nonlumines-
cent surrounding radiaxial fibrous calcite (Pl. VI: Fig. 5).
The accumulations of ostracods Pokornyopsis feifeli (Trie-
bel) developed in some remaining voids (Pl. VI: Figs. 3, 4).
These ostracods were known a long time ago (Mišík 1979) as
direct inhabitants of cavities and sea-bottom fractures (nep-
tunian dykes) but their taxonomic determination was done
only recently (Aubrecht & Kozur 1995). Many of their recent

descendants have also been found to be cave dwellers (Kor-
nicker & Sohn 1976) which is very interesting from the point
of view of their evolution and ecology. In such accumula-
tions, many of the closed ostracod shells are packed within
the remained interstitial space. The micritic matrix is then
emplaced between. Ostracod tests themselves are filled with
clear blocky calcite. The stromatolite fragments are some-
times also present in the micritic final filling.

4. Locally, if the pore connections were too small, the

voids were cemented by clear drusy sparite. Some voids even
remained empty after RFC precipitation.

Signs of karstification 

were observed in three cases:

1. The laminated sterile micrite also fills some structures

resembling neptunian dykes. The micrite is there in direct
contact with crinoidal limestone (the wall-rock). The walls
of the dykes bear signs of dissolution. They are curved
(karstified) and the opposite walls do not fit together (Pl.
VII: Figs. 1, 2). This was most probably caused by the fresh-
water dissolution. The mixed marine and fresh water might
have a similar effect (Smart et al. 1988). Because the sterile
micrite represents a relatively late filling a fresh-water inter-
ference to the marine environment is supposed. This interfer-
ence might take place through a network of cavities connect-

Plate IV: Fig. 1

— Radiaxial fibrous calcite in plain polarized

light. Note thin stromatolitic layers. Thin section. Magn. 15.5

×

.

Fig. 2

— The same under cathodoluminescence. Note the bright

luminescent zone caused by increased content Mn as a result of
temporary reducing conditions during precipitation. The numbers
point the microprobe analyses plot in Fig. 3. Fig. 3 — Microprobe
traverse across the luminescent zone in RFC (above). Note the rel-
atively increased content of MnO which is the main activator of
luminescence.

Plate III: Fig. 1

— Distinctly wavy laminated stromatolite cover-

ing, faintly laminated to structureless stromatolite (lower right).
Thin section. Magn. 27

×

Fig. 2 — Peloids to pseudopeloids prob-

ably of microbial origin in the laminated stromatolite. Thin sec-
tion. Magn. 27

×

 . Fig. 3 — Mutual overlapping of several stroma-

tolitic generations. Note the transition from the crinoidal
limestone (c) through crinoidal laminated limestone (l) to the stro-
matolite (s). Thin section. Magn. 4.4

×

Fig. 4 — Fine-grained

breccia composed of detrital crinoidal limestone (bottom) as well
as the stromatolitic and microbialitic detritus (arrows) displaying
later sedimentary reworking of all components. Thin section.
Magn. 7

×

.

§

Table 1: 

Measured composition of the acicular fringe overgrowths

on the bositra shells.

t

n

i

o

P

O

e

F

O

n

M

O

r

S

O

g

M

O

a

C

1

1

1

.

0

4

.

0

3

0

.

0

5

.

0

4

0

.

6

5

2

8

0

.

0

4

0

.

0

0

6

2

.

0

3

5

.

5

5

3

9

0

.

0

1

1

.

0

2

0

.

0

6

1

.

0

3

0

.

4

5

4

2

1

.

0

6

0

.

0

3

0

.

0

1

2

.

0

4

3

.

6

5

5

1

1

.

0

6

0

.

0

4

0

.

0

1

2

.

0

3

6

.

6

5

6

1

1

.

0

4

0

.

0

4

0

.

0

5

2

.

0

3

4

.

6

5

7

1

1

.

0

4

0

.

0

6

0

.

0

1

4

.

0

2

1

.

6

5

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PLATE III                                                                                                  77

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78                                                                                                 PLATE IV

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PLATE V                                                                                                  79

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80                                                                                               PLATE VI

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INDICATIONS OF THE MIDDLE JURASSIC EMERGENCE                                                       81

ing both marine and fresh-water zones. Modern submarine
caves are often formed in such mixing-zones (Smart et al. l.c.).

2. The above mentioned opinion is also supported by the

case, where the RFC calcite crystals, surrounding a void
filled by sterile micrite, bear signs of gravity-influenced cor-
rosion (Pl. VII: Figs. 3, 4). It is clear, that the RFC calcite, as
a marine precipitate, was later corroded by the solutions un-
dersaturated with respect to the CaCO

(at least to the high-

magnesian calcite).

3. An isolated block was found with the appearance of

laminated limestone intercalated by irregular RFC calcite
veins (Fig. 4). The laminae are frequently formed by the
Pokornyopsis 

shells, which indicates sedimentation in a larg-

er-sized cavern. The presence of such blocks supports the
theory that a large portion of breccia may represent a cavern
collapse breccia, rather than scarp breccia. However, this
question requires further investigations, not yet involved in
this paper.

Oxygen and carbon isotope data

Most of the data obtained by the oxygen and carbon iso-

tope analysis of all the cements (Table 2), when plotted in the

δ

13

C versus 

δ

18

O diagram, are concentrated in two groups

(Fig. 5).

The first and the most numerous one occurs near the mean

value estimated for the carbonates precipitated from normal
Jurassic marine water (Lohmann 1988, Fig. 2.8). The varia-
tion of 

δ

13

C between 1.8 and 3.3 ‰ PDB is relatively small.

Plate VI: Fig. 1

— “Umbrella” effect - non-recrystallized micrite

preserved under vaulted Bositra shells. Callovian part of void fill-
ing. Thin section. Magn. 27

×

Fig. 2 — Acicular fringes grown on

Bositra 

shells, with peculiar square terminations resembling an

aragonitic cement. Thin section. Magn. 27

×

Fig. 3 — Transition

from the crinoidal initial void filling (c-v) to packstone composed
of shells of cavity dwelling ostracods Pokornyopsis feifeli (Trie-
bel) (o). The contact with clast of crinoidal limestone (above - c)
coated with faintly laminated stromatolite (s) and radiaxial fibrous
calcite (r). White arrow shows a tangentially cut shell (Fig. 4 in
detail). Thin section. Magn. 4.5

×

Fig. 4 — Detailed view of the

tangentially cut shell of Pokornyopsis feifeli (see Fig. 3). Thin sec-
tion. Magn. 45

×

Fig. 5 — CL view on the non-luminescent radi-

axial fibrous calcite surrounding a void with dull orange lumines-
cent sterile micrite. Thin section. Magn. 47.5

×

.

Plate V: Fig. 1

— Clasts of crinoidal limestones (top and bottom)

cemented together by the radiaxial fibrous calcite. Note that upper
clast is coated with faintly laminated stromatolite. Thin section.
Magn. 4.5

×

Fig. 2 — Clasts of crinoidal limestones cemented by

radiaxial fibrous calcite. Like in the previous picture, thin stroma-
tolite is developped on one clast (bottom). The stromatolitic coat-
ing is sharply discontinuous due to later reworking. Thin section.
Magn. 4.5

×

Fig. 3 — Polished slab displaying the void among the

clasts filled initially by the crinoidal detritus, later by the filamen-
tous packstone (f). The change of filling is due to the facial change
induced by the sea-level rise at the Bathonian-Callovian boundary.
Other explanations see Plate I. Fig. 4 — Detailed view on the con-
tact between clast of crinoidal limestone (c) coated by radiaxial fi-
brous calcite (r) with crinoidal limestone as a void filling (c-v).
Thin section. Magn. 4.5

×

.

Table 2: 

Isotopic composition of the carbonate cements.

Fig. 4. 

Block of laminated limestone with laminae (arrow) con-

taining numerous shells of Pokornyopsis feifeli (Triebel) indicat-
ing sedimentation in a larger cavity. The limestone is penetrated
by several RFC veins (positively weathered).

§

Fig. 5. 

Measured isotopic values 

δ

18

O plotted versus 

δ

13

C.

Sample

Cement

d

13

C

(‰PDB)

d

18

O

(‰ PDB)

HSS I 4

stromatolite - 1st generation

-4.1

-4.5

1/96/2

stromatolite - 1st generation

-4.5

-5.8

HSS I 1

stromatolite - 2nd generation

2.5

-1.4

HSS I 2

stromatolite - 2nd generation

3.1

0.3

HSS I 3

stromatolite - 2nd generation

3.1

-1.6

HSS I 6

stromatolite with crin.detritus

2.8

0.2

HSS I 10 RFC calcite

2.9

-1.5

1/96/1

RFC calcite

2.7

0.1

HSS I 8

crinoidal limestone (clast)

2.9

-1.7

HSS I 9

crinoidal limestone (void)

2.8

0.2

HSS I 5

void with Pokornyopsis sp.

3.2

0.4

HSS I 7

blocky calcite

3.0

-3.2

HSS I 11 blocky calcite

3.3

-0.2

1/96/3

blocky calcite

1.8

-2.1

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82                                                                                               PLATE VII

background image

INDICATIONS OF THE MIDDLE JURASSIC EMERGENCE                                                       83

The wider range of the 

δ

18

O, varying between –5.8 and

0.4 ‰ PDB probably resulted from the temperature varia-
tions during the precipitation of individual cements.

The second group consists of only two samples taken from

the first generation of stromatolites (the number of measured
samples was limited by other factors than the rarity of occur-
rence; I hope, in spite of this, the results are reliable enough).
They display a considerable depletion of 

13

C and slight de-

pletion of 

18

O, with 

δ

13

C varying between –4.1 and –4.5,

δ

18

O from –4.5 to –5.8. Such values are typical for the car-

bonates precipitated from meteoric waters (enrichment of the
light carbon isotopes is mostly due to the pedogenic process-
es). This result represents the first evidence of Jurassic fresh-
water precipitated carbonates in the Pieniny Klippen Belt
and in the whole Western Carpathians.

Discussion

The described breccia differs from the Krasín Breccia

Member in the type locality mainly by the complex cement
filling and by the signs of karstification. It bears signs of re-
peated freshwater influence resulting in dissolution or ce-
mentation. However, some freshwater isotopic record could
remain unrecognized, particularly in the cases of high rock-
water interaction or the total absence of soil cover (the
source of lighter carbon isotopes). Nevertheless, the possibil-
ity that two generations of stromatolites differing isotopical-
ly were formed in different environment, seemlikely. The
first one was most probably formed during the
Bajocian-Bathonian emergence of the relatively rapidly lithi-
fied crinoidal limestone. The clasts derived from this lime-
stone were initially cemented by the freshwater stromatolites
probably in some stream or spring area. Such Recent stroma-
tolites were dealt with many times in literature (in Western
Carpathians for example Mišík 1982, recently also by Szulc
& Smyk 1994). However, the examined locality is so far the
only one containing Jurassic freshwater stromatolites in the
Western Carpathians.

Other registered signs of freshwater influence (dissolution-

al features) postdate (or are partially synchronous with) the
precipitation of radiaxial fibrous calcite and predate micritic
void filling. As mentioned earlier, this might be a result of
freshwater interference through the network of cavities
(karstic or extensional fractures) some of which are repre-
sented by the  present-day neptunian dykes occurring fre-
quently in the Czorsztyn Unit. This interference ceased com-
pletely with submergence of the Czorsztyn Ridge during the
Callovian-Oxfordian sea-level rise. The submergence is re-

corded by the facial changes as well as by the ending of the
siliciclastic influx to the basin.

Conclusion

From recently available data, the following evolution can be

reconstructed:

1. Crinoidal limestone was locally gradually emerged. The

gradual shallowing was recorded in the laminated stromato-
lites with crinoidal detritus. Emergence and erosion then fol-
lowed.

2. The clasts were partly coated with stromatolite coatings

in the freshwater environment (spring or stream) and then re-
worked.

3. After placing in marine conditions the second genera-

tion of stromatolites was formed.

4. Later, after stabilization of the sediment, the isopachous

radiaxial calcite cement precipitated in a marine environment.
Even in this stage, the freshwater interference took place prob-
ably through the extensional fracture network. This resulted in
the formation of small karstification features.

5. The remaining voids of breccia were then filled by

crinoidal detritus, later by mudstone containing tiny Bositra
shells. The final filling was represented by micrite frequently
containing cavity dwelling ostracods Pokornyopsis feifeli
(Triebel). Some relatively closed small pores were cemented
by blocky calcite; some of them remained empty.

As the examined problem is not yet exhausted and every

new sample brings new data, the future may bring some new
discoveries in this locality. However, I hope that the main
ones are already comprised herein.

Acknowledgements: 

The author is grateful to Dr. J. Soták

for invaluable help with the arrangement of isotope analyses
and for reviewing the paper. My thanks also belong to Prof.
M. Mišík, Dr. M. Sýkora, Dr. J. Szulc (Kraków) for many
useful consultations. Dr. M. Krobicki (Kraków) is gratefully
acknowledged for his very kind hospitality during the excur-
sion in the Polish part of the Pieniny Klippen Belt, as well as
for the critical reviewing of this paper. The latter is also true
for Dr. J. Michalík. Isotope analyses of Dr. J. Hladíková
(Prague), microanalyses of Dr. J. Krištín and CL examina-
tions of Dr. M. Wagreich (Wien) are also gratefully acknowl-
edged. This paper benefitted from the GHD (1/1812/94)
grant of the GAV agency as well as from the project “Geody-
namic evolution of the Western Carpathians” managed by the
Geological Survey of Slovak Republic.

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§

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