GeolCarp_Vol61_No2_121

www.geologicacarpathica.sk

GEOLOGICA CARPATHICA, APRIL 2010, 61, 2, 121—128 doi: 10.2478/v10096-010-0005-4

Organic-walled dinoflagellate cysts as a tool to recognize

carbonate concretions: an example from Oligocene flysch

deposits of the Western Carpathians

MARCIN BARSKI and MACIEJ BOJANOWSKI

University of Warsaw, Institute of Geology, Al. Żwirki i Wigury 93, 02-089 Warsaw, Poland; marbar@uw.edu.pl; mcbojan@uw.edu.pl

(Manuscript received March 25, 2009; accepted in revised form December 11, 2009)

Abstract: Carbonate concretions found within the Krosno shales (Polish Outer Carpathians) have formerly been inter-
preted as limestone exotics. Both the concretions and the host shales yield well preserved organic-walled dinoflagellate
cysts. The dinoflagellate cyst assemblages provide valuable age-diagnostic information: they indicate a mid-Oligocene
age and prove the concretionary origin of the carbonates. Detailed analysis of relative abundance, biodiversity and
paleoecology of the dinoflagellates from concretions provides additional information on the sedimentary environment
and the model of concretion formation.

Key words: Oligocene, Western Carpathians, biostratigraphy, concretions, organic-walled dinoflagellate cysts.

Introduction

The  shaly  Krosno  Formation  of  the  Outer  Carpathians  is
abundant in carbonate rocks of various origins. Most of them
undoubtedly  represent  exotics  (e.g.  Dżułyński  &  Ślączka
1958; Ślączka 1961; Ślączka & Wieser 1962; Mochnacka &
Tokarski  1972;  Burtan  et  al.  1984),  especially  those  which
contain  fauna  stratigraphically  different  from  the  host  rock.
Besides exotics, pelagic coccolith limestones (e.g. Haczewski
1989)  and  concretions  (e.g.  Narębski  1956;  Bojanowski
2001)  have  been  noted;  these  in  turn  should  contain  bios-
tratigraphic  assemblages  of  the  same  age  as  the  host  rocks.
Carbonate  concretions  are  usually  rounded  bodies,  which
may resemble reworked limestone blocks. These two geneti-
cally  distant  rocks  types,  carbonate  concretions  and  lime-
stone  exotics,  may  be  easily  mixed  up  if  clear  diagnostic
sedimentological features are absent.

This was the case of carbonate rocks from the Krosno

shales from the Świątkowa Wielka tectonic window (Polish
Outer Carpathians) (Fig. 1). These carbonates have been re-
ported  by  many  authors  (Kozikowski  1956;  Jurkiewicz  &
Karnkowski 1959; Koszarski 1985; Kopciowski et al. 1997)
and  regarded  as  limestone  exotics  or  tectonically  detached
blocks.  Kopciowski  et  al.  (1997)  determined  the  age  of  the
host  shales  (latest  Early  Oligocene)  on  the  basis  of  nanno-
plankton assemblages, but did not analyse the age of the car-
bonates  themselves.  Recently,  the  carbonates  have  been
thoroughly  examined  by  Bojanowski  (2001),  who  showed
that they are authigenic rocks formed by intensive methane-
induced calcite precipitation.

This paper shows that intergrated biostratigraphic and pet-

rographic  analysis  is  an  appropriate  tool  for  distinguishing
carbonate  concretions  formerly  regarded  as  limestone  exot-
ics. This approach was applied to authigenic carbonates from
the  Krosno  Formation  from  Świątkowa  Wielka  and  the  re-
sults are presented here.

Fig. 1. Location of the study area (after Mastella & Rubinkiewicz
1998).

122

BARSKI and BOJANOWSKI

The microfossil assemblages examined are dominated by

organic-walled  dinoflagellate  cysts.  Previous  palynological
studies in the Outer Carpathians (Van Couvering et al. 1981;
Gedl  1999)  showed  a  significant  impoverishment  of  the  Oli-
gocene dinoflagellate assemblages in the region. This is espe-
cially  the  case  in  the  Menilite  Formation,  which  is  the
facies-isochronic  equivalent  of  the  Krosno  Formation.  The
few  records  of  organic-walled  dinoflagellate  cysts  from  the
Krosno  Formation  (Gedl  1999)  show  poorly  diversified  as-
semblages, dominated by Deflandrea sp. Therefore, this work
was  also  focused  on  contributing  to  the  record  of  organic-
walled  dinoflagellate  cyst  assemblages  from  the  Paleogene
rocks and on the verification of their applicability for biostrati-
graphic  dating  in  the  Outer  Carpathians.  Well-preserved  as-
semblages were expected to be found within the concretions.
The  results  of  the  detailed  analysis  of  the  organic-walled  di-
noflagellate cyst assemblages allowed not only the age deter-
mination of the succession, but also showed the characteristics
of the diagenetic conditions of concretion formation.

Geological setting

The rocks examined consist of shales of the Krosno Forma-

tion which contain various authigenic carbonates. They occur
in the Grybów Unit that crops out from beneath the Magura
Nappe in the Świątkowa Wielka tectonic window of the Outer
Western Carpathians (Fig. 1). The succession examined crops
out along Krokowy stream (Fig. 1). The thickness of the suc-
cession is difficult to determine precisely due to tectonic de-
formations. It is estimated to be between 80 and 110 m.

The Krosno shales are represented by grey to black calcare-

ous  mudstones  composed  of  two  types  of  laminae:  turbiditic
and  hemipelagic.  The  laminated  limestone  is  a  20-cm-thick
bed  deposited  mainly  due  to  increased  pelagic  deposition  of
coccoliths. It is composed of a series of brown and grey thin
laminae containing fish remains. The concretions are regular,
rounded bodies with diverse morphologies, but never spheri-
cal (Bojanowski 2001). The carbonate fraction of the concre-
tions  constitutes  75—90  weight  %,  and  is  represented  almost
exclusively  by  concretionary  cements.  Detrital  material  en-
closed within them is analogous to the mineralogical composi-
tion  of  the  surrounding  shales.  Three  types  of  carbonate
concretions have been distinguished:

Dolomite concretions: beige-coloured laminated concre-

tions that may coalesce to form nodular layers. The detrital
material enclosed within them is generally silt and the scarce
lamination is sometimes cut by burrows. They occur in the
lower part of the section.

Calcite concretions type A: blueish-grey concretions with

brown rims and hollow septarian cracks. The cemented detri-
tal material is predominantly silty quartz, while clay minerals
occur less frequently. These concretions occur in the middle
part of the section.

Calcite concretions type B: laminated concretions, with

brown and grey laminae. The grey laminae are similar in min-
eralogical composition to that of calcite concretions type A.
The brown laminae contain mainly clay minerals with minor
additions of clayey quartz, as well as planktonic foraminifers,

coccoliths  and  kerogen,  whereas  the  grey  laminae  contain
more  quartz  than  clay  minerals  and  are  devoid  of  bioclasts.
The lamination is parallel and only rarely shows slight deflec-
tion in the outermost parts of the concretions. Well-preserved
trace-fossils, represented by burrows filled with reworked ma-
terial from both kinds of laminae, are not uncommon. Individ-
ual  concretions  reveal  septarian  cracks  which  may  be  filled
with brown blocky calcite. These concretions occur in the up-
per part of the section.

Material and methods

The analysis is based on ten palynological samples because

of  a  limited  number  of  reliable  exposures  within  the  stream
banks. Seven samples were collected directly in the outcrops
and  they  can  be  ordered  in  the  following  stratigraphic  se-
quence:  1  and  2   3  and  4   5   6   7  (Fig. 2).  The  three
remaining  samples  (8, 9, 10  –  calcite  concretions  type B)
were collected from stream rubble. These three samples most
probably come from the upper part of the section above calcite
concretions found in-situ (Fig. 2) and they could represent the
youngest  deposits  of  the  succession.  Samples  number 6,  8,  9
and 10 come from calcite concretions type B, sample 3 from a
calcite  concretion  type A,  sample 1  from  a  dolomite  concre-
tion,  samples 2,  4  and  7  from  the  shales,  and  sample 5  from
the coccolith limestone bed.

Palynological samples were prepared according to the stan-

dard techniques following Poulsen et al. (1990), involving
HCl and HF treatment, sieving through a 20-µm sieve and
heavy liquid separation (ZnCl

). Glycerine jelly was used as a

mounting medium. Microphotographs were taken using a

Fig. 2. Geological section with samples distribution.

123

ORGANIC DINOCYSTS FROM CARBONATE CONCRETIONS (OLIGOCENE FLYSCH OF W CARPATHIANS)

Zeiss Axioskop microscope with an interference-contrast fa-
cility. England Finder coordinates are provided for all the
specimens illustrated.

All the samples yielded organic-walled dinoflagellate

cysts. As a restricted amount of samples from different rocks
types was available for palynological analysis, the di-
noflagellate cyst range chart is provided for qualitative pur-
poses only. In some cases less than 100 specimens per slide
were recovered, therefore this might have led to anomalous
quantitative values.

Generally the dinocysts have not been affected by thermal

maturation, oxidation or biological degradation. A total of 56
taxa have been recorded in this study (Figs. 3, 4; Table 1). The
earlier Paleogene species, Adnatosphaeridium multispinosum,
and  Glaphyrocysta  ordinata,  as  well  as  the  Late  Cretaceous
Chatangiella sp. and the Jurassic Tubotuberella sp. have been
reworked.  A  minor  quantity  of  other  palynomorphs  such  as
spores,  pollen,  acritarchs,  prasinophytes  and  microforamini-
feral linings are present in the studied slides.

A dinoflagellate cyst zonal scheme has not yet been estab-

lished  for  the  Paleogene  succession  of  the  Polish  Outer  Car-
pathians. Therefore, biostratigraphical diagnosis in the present
work had to be based on published dinocyst taxa ranges (Haq
et  al.  1987;  Kothe  1990;  Powell  1992;  Brinkhuis  &  Biffi
1993; Wilpshaar et al. 1996; Gedl 2000; Gradstein et al. 2004;
Williams et al. 2004). Determination of the ages of the assem-
blages recovered (Fig. 5) has been based on the co-occurrenc-
es  of  ranges  of  well-known  taxa,  and  on  comparison  to
dinocyst zones (Powell 1992; Gradstein et al. 2004; Williams
et al. 2004).

Dinocyst assemblages and age assignment

Sample 1 comes from a dolomite concretion collected from

the lowermost part of the section. The dinocyst assemblage re-
covered consists of 18 species. The stratigraphically most sig-
nificant species include Deflandrea phosphoritica, Wetzeliella
gochtii and Memhranophoridium aspinatum.

Age: According to Williams et al. (2004) and Gradstein et

al. (2004), the presence of Wetzeliella gochtii indicates a range
from the lowermost Rupelian to the mid part of the Chattian
–  lower  part  of  subzone C  of  Zone  D15  (Gradstein  et  al.
2004).  Following  Powell  (1992),  the  first  occurrence  datum
(FOD) of Wetzeliella gochtii marks the base of dinocyst bio-
zone Wgo (lower Rupelian), which corresponds to the base of
the  calcareous  nannofossil  biozone  NP22.  The  upper  bound-
ary  of  the  assemblage  depends  on  the  interpretation  of  the
ranges  of  Deflandrea  phosphoritica  and  Wetzeliella  gochtii.
According  to  Powell  (1992),  the  top  of  the  stratigraphical
range of Wetzeliella gochtii correlates with the top of the Pcr
Zone, which corresponds to the Rupelian/Chattian boundary.
The LOD (last occurrence datum) of Deflandrea phosphoriti-
ca lies within the Hfl Zone, and coincides with the boundary
between  the  NP24  and  NP25  nannoplankton  Zones  (lower
Chattian).

Sample 2 comes from the shales present in the lowermost

part of the section close to sample 1. In total, 23 species were
recognized in the sample. The following species are of strati-

graphical importance: Chiropteridium lobospinosum, Deflan-
drea phosphoritica, Chiropteridium galea, Wetzeliella
gochtii, Wetzeliella symmetrica and Thallasiphora pelagica.

Age: Considering the occurrence of Chiropteridium lobos-

pinosum, Wetzeliella symmetrica and Thallasiphora pelagica,
the stratigraphic range of the sample embraces the lower Ru-
pelian – upper part of subzone A of Zone D14 to the lower-
most Chattian – mid part of subzone B of Zone D15
(Gradstein et al. 2004).

Folloving Powell (1992), the stratigraphical range of this as-

semblage is determined by the FOD of Chiropteridium lobos-
pinosum and the LOD of Wetzeliella gochtii, which limit the
range of the assemblage to the Pcr dinoflagellate Zone, corre-
sponding to the upper Rupelian.

Sample 3 was taken from the calcite concretion type A and

yielded a very poor, low-diversity dinocyst assemblage. Only
sixteen specimens, represented by Homotriblium sp. and Thal-
lasiphora pelagica, were found.

Age: According to Gradstein et al. (2004), the LOD of the

latter species is not later than the earliest Chattian within the
upper part of subzone B of Zone D15.

Sample 4. The assemblage from this sample consists of 18

species. The biostratigraphically most significant species in-
clude Wetzeliella symmetrica, Chiropteridium lobospinosum
and Thallasiphora pelagica.

Age: The FOD of Chiropteridium lobospinosum marks the

upper  part  of  subzone A  of  zone D14  within  the  Rupelian,
whereas the two other species terminate their occurrence with-
in  the  lowermost  Chattian  in  subzone B  of  Zone D15  (Grad-
stein  et  al.  2004).  According  to  Powell  (1992),  the  FOD  of
Chiropteridium  lobospinosum  defines  the  lower  boundary  of
the  Pcr  Zone  and  the  LOD  of  Wetzeliella  symmetrica  corre-
lates with the base of the Hfl Biozone, which is considered to
be coeval with the top of the nannoplankton Zone NP24. This
means that the age of the sample embraces a range from the
upper part of the Rupelian to the lower part of the Chattian.

Sample 5 from the coccolith limestone yielded a poor,

low-diversity assemblage composed of Systematophora pla-
cacantha (20 specimens) and Chiropteridium lobospinosum
(5 specimens).

Age: The presence of the latter species limits the range of

the  assemblage  to  subzone A  of  Zone D14  within  the  Rupe-
lian and to subzone C of Zone D15 of the Chattian (Gradstein
et  al.  2004).  According  to  Powell  (1992),  the  same  species
marks the Pcr, Lxa and the lower Hfl dinoflagellate biozones.
In  both  cases  the  biozones  correspond  to  the  upper  Rupelian
up to the lower Chattian.

Sample 6. The assemblage recognized in sample 6 from

calcite concretion type B is composed of 9 species (54 speci-
mens). Chatangiella sp. (Late Cretaceous) is reworked.

Age: The stratigraphical range of the assemblage is deter-

mined by Chiropteridium lobospinosum, and is similar to the
range stated for sample 5.

Sample 7 was collected from the uppermost part of the sec-

tion. Only 5 taxa were recognized: Homotryblium aculeatum,
Homotryblium sp., Phelodinium sp., Rhombodinium draco,
and Wetzeliella sp. A.

Age: Rhombodinium draco marks the top of Zone D14

which corresponds to the mid part of the Rupelian (Will-

125

ORGANIC DINOCYSTS FROM CARBONATE CONCRETIONS (OLIGOCENE FLYSCH OF W CARPATHIANS)

iams et al. 2004; Gradstein et al.
2004).

Samples 8, 9 and 10 representing

calcite concretion type B were col-
lected from stream rubble.

Sample 8 yielded a rich, high-di-

versity assemblage. A total of 20 spe-
cies were recognized, with all but one
characteristic of the Oligocene; only
Adnatsphaeridium multispinosum is a
reworked Late Eocene species.

Age: The most precise stratigraphic

interval  represented  by  the  sample  is
based  on  the  occurrence  of  two  spe-
cies:  Chiropteridium  galea  and  Chi-
ropteridium lobospinosum. According
to  Gradstein  et  al.  (2004),  the  latter
species indicates a stratigraphic inter-
val in the range between subzone A of
Zone D14  within  the  Rupelian  and
subzone C of Zone D15 of the Chatti-
an.  Chiropteridium  galea  confirms
this  interval,  although  this  species  fi-
nally disappears within the uppermost
Chattian.

Sample 9 yielded the highest di-

versity  assemblage,  with  27  species
recognized.  However,  only  a  few  of
them  have  biostratigraphical  impor-
tance: Chiropteridium lobospinosum,
Deflandrea  phosphoritica,  Chiropte-
ridium galea, Thallasiphora pelagica,
and Memhranophoridium aspinatum.

Age: Considering the presence of

Chiropteridium  lobospinosum  and
Thallasiphora pelagica, the narrowest
stratigraphic range of the sample em-
braces  the  lower  Rupelian  –  upper
part of subzone A of Zone D14 to the
lowermost  Chattian  –  mid  part  of
subzone B of Zone D15 (Gradstein et
al.  2004).  Other  species  listed  above
more or less confirm this interval.

Sample 10. Among the 11 species

of sample 10, only a few have strati-
graphical  significance.  They  include
Chiropteridium  galea,  Chiropteridi-
um  lobospinosum,  Deflandrea  phos-
phoritica,  and  Memhranophoridium
aspinatum.

Age: As in sample 9, the occur-

rence  of  Chiropteridium  lobospino-
sum  and  Thallasiphora  pelagica
suggest a stratigraphic range between
the  lower  Rupelian  –  upper  part  of
subzone A of Zone D14 and the low-
ermost  Chattian  –  mid  part  of
subzone B of Zone D15 (Gradstein et
al. 2004).

SAMPLE NR

TAXON

Apectodinium sp.

0 6 0 0 0 0 0 0 0 0

Areoligera senonensis

6 0 0 0 0 0 0 4 0 0

Areoligera sentosa

7 0 0 0 0 5 0 0

11 0

Caligodinium sp. A of Gedl (2000)

0 0 0 7 0 4 0 0 5 0

Charlesdowniea sp.

0 0 0 5 0 0 0 0 0 0

Chiropteridium galea

20 0 0 0 0 0

Chiropteridium lobospinosum

10 0 5 5 6 0

Cleistosphaeridium placacanthum

21 0 0

20 0 0

23 5

Cordosphaeridium cantharellus

0 0 0 0 0 0 0

15 6 0

Cordosphaeridium inodes

5 0 0 6 0 0 0

14 0 0

Cribroperidinium sp.

0 0 0 0 0 0 0 5 0 0

Dapsilidinium pseudocolligerum

0 0 0

14 0 0 0

10 0 0

Dapsilidinium sp.

15 0 0 0 0 0

10 0 0

Deflandrea phosphoritica

21 0

20 0 0 0 5

110

Distatodinium ellipticum

0 0 0 0 0 0 0 5 0 0

Distatodinium paradoxum

0 6 0 0 0 5 0

41 7 5

Dracodinium laszczynskii

0 0 0 5 0 0 0 0 0 0

Enneadocysta pectiniformis

0 0 0 6 0 0 0 0 0 0

Glaphyrocysta exuberans

5 0 0 0 0 0 0 0

11 0

Glaphyrocysta pastielsi

0 5 0 0 0 0 0 0

10 0

Glaphyrocysta sp.

0 0 0 0 0 5 0 0 0 0

Homotryblium abbreviatum

0 5 0

11 0 0 0 0 6 0

Homotryblium aculeatum

11 0 0 0 0 5 0

36 6

Homotryblium sp.

11 6 5 0 0 4 0 0 0

Homotryblium tenuispinosum

12 0 0 5 0 5 0 0

21 0

Hystrichokolpoma rigaudiae

0 5 0 0 0 0 0

20 7 0

Impletosphaeridium sp.

25 0

10 0 3 0

Lejeunecysta sp.

24 0 0 0 0 0 0 4 0

Lejeunecysta sp. A of Gedl (2000)

0 0 0 0 0 0 0 0 5 0

Lingulodinium machaerophorum

5 0 0 0 0 0 0

Membranophoridium aspinatum

18 0 0 0 0 0 0 0 5 5

Nematosphaeropsis lativittata

0 0 0 0 0 0 0 0 5 0

Nematosphaeropsis labyrinthus

0 3 0 0 0 0 0 0 3 0

Operculodinium sp.

30 0 5 0 0 0 5 5 0

Operculodinium uncinispinosum

11 0

14 0 0 0 0 0 0

Paleocystodinium golzowense

0 5 0 0 0 0 0 0 0 4

Phelodinium sp.

0 0 0 0 0 0 6 0 0 0

Polysphaeridium sp.

0 0 0 0 0 0 0

20 0 0

Polysphaeridium subtile

3 0 0 0 0 0 0 0 5 0

Reticulatosphaera actinocoronata

0 5 0 0 0 6 0 0 4 0

Rhombodinium draco

0 0 0 0 0 0 5 0 0 0

Rhombodinium sp. B of Gedl (2000)

6 0 0 0 0

11 0 0 0 0

Spiniferites pseudofurcatus

0 0 0 5 0 0 0 0 0 0

Spiniferites ramosus

45 0 5 0 0 0

115

Systematophora sp.

5 0 0 0 0 0 0 0 0 0

Thallasiphora pelagica

0 5

22 0 0 0 0

11 0

Vozzhennikovia sp.

0 0 0 0 0 0 0 0 5 0

Wetzeliella gochtii

17 0 0 0 0 0 0 0 0

Wetzeliella sp. A of Gedl (2000)

0 0 0 0 0 0 7 5 0 0

Wetzeliella sp. B of Gedl (2000)

0 0 0 0 0 0 0

10 0 0

Wetzeliella symmetrica

0 5 0 4 0 0 0 0 0 0

Ynezidinium cf. brevisulcatum

6 0 0 0 0 0 0 0 0 0

Dinocyst sp. A

3 0 0 0 0 0 0 0 0 0

Adnatsphaeridium multispinosum*

0 4 0 0 0 0 0 3 0 0

Chatangiella* sp.

0 0 0 0 0 2 0 0 0 0

Glaphyrocysta ordinata*

3 0 0 0 0 0 0 0 0 0

Tubotuberalla sp. (J)

0 0 0 0 0 0 0 0 5 0

Foraminiferal

test

linings

12 0 0 0 0 0 0 0 0

Tasmanites sp.

0 0 0 0 0 0 0

15 0

TOTAL/SPECIMEN

139 327 16 154 25 52 27 395 398 217

DIVERSITY

17 23 2 18 2 9 5 20 27 11

Table 1: Semi-quantitative distribution of the dinoflagellate cysts in studied samples.

127

ORGANIC DINOCYSTS FROM CARBONATE CONCRETIONS (OLIGOCENE FLYSCH OF W CARPATHIANS)

On the basis of the FOD Chiropteridium lobospinosum and

LOD of Deflandrea phosphoritica, the assemblage ranges be-
tween the base of the Pcr Biozone and the lower part of the Hfl
Biozone, corresponding to the top of Nannoplankton Biozone
NP24 (Powell 1992).

Considering the superposition of samples 1 to 7 collected

from the section, further detailed age assignment may be sug-
gested as shown by the grey block on the range chart (Fig. 5).
The stratigraphic position of the uppermost sample 7 compris-
ing the index species Rhombodinium draco delimits the upper
rages of all samples to the mid part of the Rupelian – top of
Zone D14 (Gradstein et al. 2004). Sample 2 delimits all lower
ranges of the samples to the uppermost part of subzone A of
Zone D14.  The  stratigraphic  range  of  the  lowermost  sample
begins  within  the  mid  part  of  subzone A  of  Zone D14.  The
ages  of  the  samples  collected  from  stream  boulders  must  be
assigned individually (Fig. 5).

Sedimentary environment and concretion formation

All the samples contain mixed dinoflagellate cyst assem-

blages comprising off-shore and near-shore taxa. They contain
near-shore derived genera such as Deflandrea and Homotribli-

um,  as  well  as  off-shore  genera  represented  by  Spiniferites,
Systematophora,  Nematosphaeropsis  and  Hystrichokolpoma
(Köthe 1990; Brinkhuis 1994; Pross & Brinkhuis 2005; Sluijs
et al. 2005). The recognized mixing suggests the redeposition-
al character of the studied deposits, probably executed by tur-
bidity  flows  widely  described  from  this  area  (Dżułyński  &
Ślączka 1958; Ślączka 1961; Ślączka & Wieser 1962; Moch-
nacka  &  Tokarski  1972).  Redeposition  events  are  also  con-
firmed  by  the  striking  predominance  of  Deflandrea
phosphoritica  in  sample 9  confirming  an  influx  of  proximal
sediments into the deeper part of the basin as well as by the re-
worked dinocysts present in samples 1, 2, 6, 8 comprising Ju-
rassic and Early Eocene taxa (Table 1).

The striking preservation of the dinoflagellate cysts in the

concretions,  in  contrast  to  their  significant  flattening  in  the
surrounding  shales,  implies  that  the  concretions  grew  during
early  diagenesis,  before  significant  compaction  took  place.
Fast lithification of the concretionary carbonate cements led to
the formation of a compaction-resistant framework which act-
ed as a shelter for the microfossils.

It seems that the great impoverishment of dinoflagellate cyst

assemblages and absence of other microfossils in calcite con-
cretions of type A stems from the fact that they contain much
coarser detrital material than the other carbonate concretions.
This suggests that the microfossils are more abundant within
the finer material, which is of hemipelagic origin, and in the
upper  parts  of  turbiditic  laminae.  Therefore,  it  is  concluded
that  all  the  calcite  concretions  formed  in  a  similar  way,  but
within different intervals of the section: precipitation of authi-
genic calcite within turbiditic material led to the formation of
“pure”  concretions  (type A),  whereas  laminated  concretions
(type B) originated in places where the turbiditic material was
intercalated  with  hemipelagic  laminae  rich  in  microfossils.
The brown laminae from type B calcite concretions represent
the hemipelagic material cemented by authigenic calcite.

Systematic notes

Dinocyst sp. A (Fig. 4.21)

Material: Three specimens of this species were found in

sample 1 (Table 1).

Description: Height of elongated central body is about

100 µm, and width does not exceed 60 µm. Short processes
are solid, foliating towards the ends. Archeopyle type is apical
with adnate operculum. Paratabulation formula is not evident
besides archeopyle suture.

Occurrence in the studied material: Described species

was noted from the lowermost sample (Sample 1) of the stud-
ied section. According to ranges of co-occurring species its
stratigraphical distribution is from the lower Rupelian to the
lower Chattian.

Conclusions

Biostratigraphic analysis of the dinoflagellate cysts from

the studied carbonate rocks and the Krosno shales of the Gry-

Fig. 5. Stratigraphic ranges of the samples in stratigraphic order
from the lowermost (sample 1) to the uppermost in the section
(sample 7). Dinoflagellate biozones from Powell (1992).

128

BARSKI and BOJANOWSKI

bów Unit, which crop out from beneath the Magura Nappe in
the Świątkowa Wielka tectonic window of the Outer Western
Carpathians, precludes an exotic origin of the carbonate bod-
ies. They are concretions which formed in situ within the sedi-
ment by authigenic precipitation of carbonate cements during
early diagenesis (Bojanowski 2001, 2004). This conclusion is
supported here by the preservation state and compression ratio
of the organic cyst bodies.

The dinoflagellate cyst assemblages from both the host

shales and the concretions indicate an Oligocene age.

The dinoflagellate cysts appear to be more abundant with-

in the finer material, which is of hemipelagic origin, and in the
upper parts of turbiditic laminae. This is the reason for the im-
poverishment  of  dinoflagellates  and  other  microfossils  ob-
served in “pure” calcite concretions (type A) when compared
to  their  great  abundance  in  the  laminated  calcite  concretions
(type B).  This  suggests  that  type A  calcite  concretions  were
formed by cementation of turbiditic material, whereas type B
calcite concretions grew within turbiditic material intercalated
by hemipelagic laminae.

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