GEOLOGICA CARPATHICA, 52, 6, BRATISLAVA, DECEMBER 2001
349 — 360
THE CENOMANIAN (LATE CRETACEOUS) RADIOLARIANS
FROM THE TOMALAR FORMATION, CENTRAL PONTIDES,
, LUBOV BRAGINA
, CEMAL TUNOGLU
and UGUR KAGAN TEKIN
Geological Institute of Russian Academy of Sciences, Pyzhevsky 7, 109017 Moscow, Russia; email@example.com
Geological Department, Hacettepe University, Beytepe-Ankara, Turkey; firstname.lastname@example.org
General Directorate of Mineral Research and Exploration (MTA), Geological Research Department,
06520 Balgat-Ankara, Turkey; email@example.com
(Manuscript received December 13, 2000; accepted in revised form October 4, 2001)
Abstract: The lower part of the Late Cretaceous Tomalar Formation (Devrekani Basin, Central Pontides, northern Tur-
key) is characterized by the presence of light-green ribbon cherts and cherty mudstones (approximately 10 m thick) with
abundant well-preserved Radiolaria. The presence and coexistence of such taxa as Acaeniotyle macrospina,
Archaeospongoprunum salumi, Becus horridus, Cavaspongia euganea, Dactyliodiscus longispinus, Halesium sexangulum,
Hexapyramis pantanellii, Pessagnobrachia irregularis, Pyramispongia glascockensis, Savaryella quadra, Vitorfus
brustolensis, Novixitus dengoi, N. weyli, Phalangites telum and others clearly indicate the Cenomanian age. The Tomalar
Formation covers the whole Upper Cretaceous due to the presence of Maastrichtian planktonic Foraminifera from the
upper part of this formation. The radiolarian assemblage of the Tomalar Formation correlates well with the coeval fauna
of the Western Mediterranean.
Key words: Cenomanian, Turkey, Central Pontides, Devrekani Basin, Tomalar Formation, cherts, Radiolaria.
Chert, chert-micritic, and volcanogenous-chert units are com-
monly present in various regions of Turkey. They are usually
supposed to be formed in the paleo-oceans or seas with deep-
water conditions. The age of these units are of great impor-
tance for understanding the geological history of the Mediter-
ranean mobile belt, as well as for the comprehensive analysis
of the development of oceanic basins and related ophiolite su-
ture zones. Therefore, the age data of these deposits have to be
applied for studies of regional tectonics. Cherts are poorly
characterized by macrofossils, foraminifers and other paleon-
tological remains that have prime importance for biostratigra-
phy. For this reason, many such units in various regions of
Turkey (for example, in the Pontide Orogenic Belt and in the
Izmir—Ankara—Erzincan suture zone) still have no precise
dates. Only radiolarians are very common and diverse in
cherts and cherty mudstones, and they can be utilized for solv-
ing stratigraphical problems.
The pioneering studies of the Mesozoic Radiolaria of Tur-
key (De Wever et al. 1979; Pessagno & Poisson 1981; De
Wever 1981a,b,c, 1982a,b), as well as the recent works (Bra-
gin & Tekin 1996, 1999; Tekin 1999; Mekik et al. 1999;
Mekik 2000), reflected these problems and presented valuable
data for the geology of the studied areas and for further devel-
opment of the radiolarian biostratigraphy. The cited works
covered two large stratigraphic intervals: the Middle Triassic—
Early Jurassic, and the Late Jurassic—Early Cretaceous.
This article is concerned with the first finding of the diverse
and correlative Late Cretaceous (Cenomanian) radiolarian as-
semblage from the Devrekani Basin, Central Pontide region
(northern Turkey). It should be noted that the presence of radi-
olarites and radiolarians in the Upper Cretaceous of this region
has been mentioned several times (Tunoglu 1991a, 1993, 1994),
but detailed study of siliceous microfosils has not yet been re-
alized. The Late Cretaceous Radiolaria from Turkey are inter-
esting for two reasons: firstly they provide new biostratigraph-
ic data for regional lithostratigraphic units, and secondly the
occurrence of numerous radiolarian taxa in Turkey allows the
further progress of paleobiogeography of this planktonic
group. In this study, the first preliminary data that need to be
discussed and analysed in further studies are submitted.
In this study, a chert sample from the study area was pro-
cessed using techniques suggested by Pessagno & Newport
(1972), using diluted (5—10 %) hydrofluoric acid. The extract-
ed radiolarians have been studied under the light microscope
LOMO-MBS-9. The SEM microscope Cambridge Stereoscan
600 has been utilized for more precise determinations and pho-
tographic works. All these works were realized in the Geologi-
cal Institute of Russian Academy of Sciences, Moscow.
The study area is located in the northern part of the Turkey
(north-northeast of Kastamonu City and north of Devrekani
350 BRAGIN et al.
Town) (Fig. 1). This region belongs to the “Pontide Orogenic
Belt” (Ketin 1966), or to the “Rhodope-Pontide Fragment” ac-
cording to Sengör (1984). The Pontide area is characterized by
the presence of several basins with transgressive to regressive
Jurassic, Cretaceous and Tertiary successions. One of them is
the Devrekani Basin, which represents a depression with east-
northeast trending long axis, filled by the Late Mesozoic and
Cenozoic marine sediments, covering a metamorphic base-
ment of supposed Precambrian age in the south, and Jurassic
clastics and carbonates in the north (Fig. 1). Devrekani and the
other similar basins were entirely related to the Tethyan Fau-
nal Realm. This area has been studied by numerous investiga-
tors on the terms of regional geology, biostratigraphy, litholo-
gy and tectonics (Ketin 1962, 1966; Yilmaz 1979; Aydin et al.
1986; Tunoglu 1991a,b, 1992a,b, 1993, 1994; Sagular et al.
1991; Tunoglu & Batman 1995; Tunoglu & Temel 1996).
The Late Mesozoic of the southern part of the Devrekani
Basin is represented by the following lithostratigraphic units:
The Tomalar Formation first named and defined by Tunoglu
(1991b) is represented by Late Cretaceous cherts, marls and
micritic limestones, sometimes with beds of sandstones, with
total thickness ranging from 10 to 175 meters. Synonyms of
this formation in the other region of the Central Pontides are as
follows: Unaz Formation (Akyol et al. 1994), Kirensöküsü
Formation (Yilmaz 1979), Kapanbogazi Formation (Gedik &
Korkmaz 1984) and Nasibey Limestone Member (Terlemez &
The Davutlar Formation, again first named and defined by
Tunoglu (1991b), is Latest Maastrichtian—Middle Paleocene in
age. The Cretaceous part is represented by basal conglomer-
ates, sandy limestones and sandy marls with total thickness
approximately 10—20 m (Fig. 2) (Tunoglu 1991b, 1992b).
The lowermost part of the Tomalar Formation is character-
ized by radiolarian cherts and mudstones, while the middle
and upper parts of this formation comprise two main lithologi-
cal types of limestone: wackestone/biomicrite and packstone/
intramicrite (Tunoglu 1992b). Both Tomalar and Davutlar For-
mations have erosional basal boundaries. The Tomalar Forma-
tion unconformably overlies the metamorphic basement (Gür-
leyik Gneiss of supposed Precambrian age). The Davutlar
Formation also lies on the Tomalar Formation with unconfor-
mity. In some places the Tomalar Formation is absent due to
complete erosion before the Late Maastrichtian transgression
(Fig. 1), and in such cases the Davutlar Formation lies directly
on the metamorphic basement.
According to the previous investigations, the upper part of
the Tomalar Formation in the type area, near Tomalar Village
(Fig. 1) is characterized by the presence of the Middle—Upper
Maastrichtian foraminifers such as Globotruncana folsosutu-
arti (Sigal), G. arca (Cushman), G. ventricosa (White), G. lin-
neiana (White), G. rosetta (Carsey), G. aegyptiaca (Nakkady),
Globotruncanita stuarti (De Lapparent) (determined by Vedia
Toker, Ankara University, Ankara) and nannofossils Arkhan-
gelskiella cymbiformis Vekshina, Eiffellithus gorkae Rein-
Fig. 1. Simplified geological map of the Devrekani Basin, compiled from Tunoglu (1994). 1 – Precambrian metamorphics, 2 – Jurassic
clastics and limestones, 3 – Upper Cretaceous Incigez and Tomalar Formations, 4 – Uppermost Maastrichtian to Paleogene Davutlar
Formation, 5 – Paleogene Gürleyikdere and Gurmalar Formations, 6 – Quaternary deposits, 7 – Locality of the Ürküt Section.
THE CENOMANIAN RADIOLARIANS FROM CENTRAL PONTIDES, TURKEY 351
hardt, E. parallelus Perch-Nielsen, Lithraphidites corniolensis
serratus Shumenko, L. praequadratus Roth, L. quadratus
Bramlette et Martini, Predicosphaera cretacea Gartner, P.
grandis Perch-Nielsen, P. spinosa Gartner, Rucinolithus? mag-
nus Bukry, Staurolithes laffitei Caratini, and Thoracosphaera
thoracata Keupp (determined by Enis Kemal Sagular, Süley-
man Demirel University, Isparta) (Tunoglu 1991b, 1992b).
Fig. 2. Generalized columnar section for studied area. 1 – Calc-
silicatic gneiss, 2 – Marble, dolomitic marble, 3 – Granite, dior-
ite and diorite-porphyre, 4 – Chert, 5 – Micritic limestone, 6 –
Clay, 7 – Conglomerate, 8 – Sandy limestone, 9 – Massive cor-
al limestone, 10 – Unconformity, 11 – Location of radiolarian-
bearing sample (compiled from Tunoglu 1993).
Abundant macrofossils such as bivalves, echinoids, corals
have been obtained from the lowermost part of the Davutlar
Formation. The age of the formation is Late Maastrichtian to
Early Paleocene (?) due to foraminiferal fauna such as Glo-
botruncana aegyptiaca Nakkady, G. arca (Cushman), Glo-
botruncanita stuarti (De Lapparent), Rosita consuta (Cush-
fornicata (Plummer), Globigerina fringa
(Subbotina), G. triloculinoides (Plummer) (determined by Ve-
dia Toker, Ankara University, Ankara) (Tunoglu 1991b,
1992b). The Cretaceous-Tertiary boundary is tentatively
placed in the lower part of this formation.
Lithological description of Ürküt Section
The lower part of the Tomalar Formation is represented by
radiolarian cherts intercalated with cherty mudstones and
cherty marls. These lithologies are characterized by the pres-
ence of abundant radiolarians (Tunoglu 1991a, 1993, 1994). In
this study, sample 326 (radiolarian chert) from the Ürküt Sec-
tion of the Tomalar Formation was analysed (coll. Cemal
Tunoglu, Hacettepe University, Ankara). The Ürküt Section is
located in the southern part of Devrekani Basin, between
Ürküt and Ahmetoglu villages (Fig. 1). The Tomalar Forma-
tion is relatively thin (approximately 10 m) and only the lower
part of the Tomalar Formation is present in the studied sec-
The description of the Ürküt Section is given here in as-
cending order (Fig. 3):
1. (?) Precambrian calc-silicatic gneiss, intruded by dykes
2. The Tomalar Formation. The lower part of this formation
is represented by light greenish-grey ribbon cherts (beds 5—10
cm thick) intercalated with yellowish-grey to light olive-co-
loured cherty mudstones and siltstones (beds 7—15 cm thick).
In the upper part of the unit, light-grey wackestone beds are
present. Sample 326 was collected from the lowermost ex-
posed bed of this formation. The approximate observed thick-
ness of this formation is 10 meters in the study area.
3. The Davutlar Formation. Polygenetic conglomerates with
well-rounded pebbles of granite, diorite, and gneiss are
present at the base and it gradually changes to coarse to mid-
dle-grained yellowish-grey sandstones and sandy limestones
towards the upper part.
The remarkable feature of this section is the chert deposi-
tion above the unconformity surface separating the Tomalar
Formation from the basement rock units. This fact needs addi-
tional discussion and explanation. Probably, this chert deposi-
tion was preceded by an episode of non-deposition or by a pe-
riod during which the previously formed sediments were
eroded (partly or completely). Some examples could be given
for this phenomenon.
1. The Upper Cretaceous sedimentary cover of the Troodos
Ophiolite Massif (Cyprus) starts with the unit of volcaniclas-
tic breccias and sandstones with strongly variable thickness
depending on the surface relief of underlying volcanics (Rob-
ertson & Hudson 1974; Simonian & Gass 1978; Osozawa &
Okamura 1993). The overlying Turonian-Campanian Perape-
dhi Formation consists of deep-water metalliferous sediments
352 BRAGIN et al.
(umbers) and radiolarian cherts (Mantis 1970; Robertson &
Woodcock 1979; Blome & Irwin 1985; Urquhart & Banner
1995; Bragina & Bragin 1996). In some areas (for example, in
the southern flank of the Limassol Forest Massif, central Cy-
prus) the unit of volcaniclastic breccias is not present and the
Turonian radiolarian cherts directly lie on the eroded surface
of the upper pillow lavas of the ophiolite complex (Blome &
2. The Jurassic Episkopi Formation (southwestern Cyprus)
overlies the Upper Triassic Vlambouros Formation (Swarbrick
& Robertson 1980). Uppermost part of the Vlambouros For-
mation is represented by Upper Norian to Rhaetian sand-
stones, siltstones and occasional micritic limestones (Bragin &
Krylov 1996). The lowermost part of the Episkopi Formation
includes Middle Jurassic radiolarian cherts. The lower contact
of the Episkopi Formation is clearly erosional and exhibits lat-
eral undulation (Bragin & Krylov 1996). Therefore, the depo-
sition of Middle Jurassic radiolarian cherts was preceded by a
period of erosion or non-deposition, and a large stratigraphic
gap (including the whole Lower Jurassic) appeared.
Radiolarian assemblage – discussion and
The radiolarian assemblage from sample 326 is character-
ized by the presence of the following taxa: Hexapyramis pan-
tanellii Squinabol, Hexapyramis sp. ex gr. H. pantanellii
Squinabol, Acastea sp. cf. A. diaphorogona (Foreman), Acae-
niotyle macrospina (Squinabol), Archaeocenosphaera? mel-
lifera O’Dogherty, Staurosphaeretta wisniovskii (Squinabol),
S. micropora (Squinabol), Protoxiphotractus sp. cf. P. vento-
sus O’Dogherty, P. sp., Paronaella solanoensis Pessagno, P.
sp., Halesium sp. cf. H. diacanthum (Squinabol), H. quadra-
tum Pessagno 1971, H. sexangulum Pessagno, Patulibracchi-
um woodlandensis Pessagno, Pessagnobrachia irregularis
(Squinabol), Crucella aster (Lipman), C. irwini Pessagno, C.
messinae Pessagno, Savaryella quadra (Foreman), S. sp. aff.
S. spinosa O’Dogherty, S. sp., Mesosaturnalis hueyi (Pessag-
no), Acanthocircus impolitus O’Dogherty, Vitorfus brustolen-
sis (Squinabol), Cavaspongia californiaensis Pessagno, C.
euganea (Squinabol), Pyramispongia glascockensis Pessagno,
Alievium sp., Becus horridus (Squinabol), Pseudoaulophacus
sp. aff. P. sculptus (Squinabol), P. sp., Patellula sp. aff. P. he-
lios (Squinabol), Dactyliodiscus longispinus (Squinabol), Go-
dia sp. aff. G. concava (Li et Wu), G. lenticulata Jud, G. sp. cf.
G. lenticulata Jud, Dactyliosphaera sp. ex gr. D. maxima (Pes-
sagno), Archaeospongoprunum salumi Pessagno, Archaeodic-
tyomitra sliteri Pessagno, A. sp. ex gr. A. sliteri Pessagno, A.
sp. cf. A. squinaboli Pessagno, Obelisciotes sp. aff. O. turris
(Squinabol), Xitus antelopensis Pessagno, Novixitus dengoi
Schmidt-Effing, N. weyli Schmidt-Effing, Amphipyndax stocki
(Campbell et Clark), Stichomitra sp. ex. gr. S. alamedaensis
Fig. 3. Ürküt Section from the Tomalar Formation. 1 – (?) Precambrian metamorphic basement, 2 – Dyke of diorite-porphyre, 3 –
Cherts and cherty mudstones of the Tomalar Formation, 4 – Sandy limestones and marls of the Davutlar Formation, 5 – Basal con-
glomerate of the Davutlar Formation, 6 – Quaternary slope deposits, 7 – Sample locations, 8 – Unconformity.
Fig. 4. Scanning electron micrographs of the radiolarians from
the Devrekani region. 1 – Hexapyramis pantanellii Squinabol;
Scale bar = 100 µm. 2 – Hexapyramis sp. ex. gr. H. pantanellii
Squinabol; Scale bar = 200 µm. 3 – Acastea sp. cf. A. diaphorog-
ona (Foreman); Scale bar = 100 µm. 4 – Acaeniotyle macrospina
(Squinabol); Scale bar = 100 µm. 5—6 – Archaeocenosphaera?
mellifera O’Dogherty; Scale bar for all figures = 100 µm. 7 –
Staurosphaeretta wisniovskii (Squinabol); Scale bar = 200 µm. 8—
9 – Staurosphaeretta microporus (Squinabol); Scale bar for all
figures = 200 µm. 10 – Protoxiphotractus sp. cf. P. ventosus
O’Dogherty; Scale bar = 100 µm. 11 – Protoxiphotractus sp.;
Scale bar = 100 µm. 12—13 – Paronaella solanoensis Pessagno;
Scale bar respectively = 100, 200 µm. 14 – Paronaella sp.,
Scale bar = 100 µm. 15 – Halesium sp. cf. H. diacanthum
(Squinabol); Scale bar = 100 µm. 16 – Halesium quadratum Pes-
sagno; Scale bar = 155 µm. 17 – Halesium sexangulum Pessag-
no; Scale bar = 100 µm. 18—19 – Patulibracchium woodlanden-
sis Pessagno; Scale bar respectively = 200, 100 µm. 20 –
Pessagnobrachia irregularis (Squinabol); Scale bar = 100 µm.
21—22 – Crucella aster (Lipman); Scale bar for all figures = 100
µm. 23 – Crucella messinae Pessagno; Scale bar = 100 µm. 24
– Crucella irwini Pessagno; Scale bar = 100 µm.
THE CENOMANIAN RADIOLARIANS FROM CENTRAL PONTIDES, TURKEY 353
354 BRAGIN et al.
THE CENOMANIAN RADIOLARIANS FROM CENTRAL PONTIDES, TURKEY 355
(Campbell et Clark), Stichomitra communis Squinabol, and
Phalangites telum O’Dogherty (Figs. 4—6). Some planktonic
foraminifers were also derived from the same sample, but they
are non-determinable due to poor preservation. Elements of
Porifera (macroscleres and microscleres) were not indicated,
as well as other remains of benthic fossils.
A radiolarian assemblage was derived only from one sam-
ple, and we cannot study now the vertical distribution of radi-
olarian taxa in the section. Therefore, we can present here only
initial data on these fossils. Anyway, the recovered assem-
blage is characterized by good preservation, abundance and
taxonomic diversity. It allows us to present general informa-
tion about this assemblage, to compare and to correlate it with
previously described coeval associations, and to use these data
for new biostratigraphic interpretations.
All listed radiolarian species have good preservation and
were probably not affected by any redeposition, sorting or par-
tial dissolution. This conclusion is based on the fact that very
thin and delicate shells or their parts (long thin spines, thin
rings of Saturnalidae) are well preserved. Some large network-
like radiolarian shells were also obtained. These data may re-
flect very calm depositional conditions of cherts that were
probably formed by slow background planktonogenic sedi-
mentation in the relatively deep-water environment. Absence
of benthic remains (Porifera elements) also supports these con-
The major part of the taxonomic composition of the studied
assemblage (38 species, including those determined in open
nomenclature) is represented by spumellarians. Only 11 nas-
sellarian species were obtained. One might suppose that this
taxonomic domination of Spumellaria could be interpreted
here as a feature of a relatively shallow-water environment.
On the contrary, some previously described Cenomanian radi-
olarian assemblages also exhibit taxonomic domination by
Spumellaria. For example, the Cenomanian associations re-
covered from relatively deep-water lithologies of Northern
Apennines (O’Dogherty 1994) have 113 spumellarian and 91
nassellarian species. Therefore, such a feature as the taxonom-
Fig. 5. Scanning electron micrographs of the radiolarians from the
Devrekani region. 1 – Savaryella quadra (Foreman); Scale bar =
100 µm. 2 – Savaryella sp. aff. S. spinosa O’Dogherty; Scale bar =
100 µm. 3 – Savaryella sp.; Scale bar = 100 µm. 4—5 – Mesosatur-
nalis hueyi (Pessagno); Scale bar for all figures = 100 µm. 6 – Acan-
thocircus impolitus O’Dogherty; Scale bar = 100 µm. 7 – Vitorfus
brustolensis (Squinabol); Scale bar = 40 µm. 8—9 – Pyramispongia
glascockensis Pessagno; Scale bar for all figures = 100 µm. 10—11 –
Cavaspongia euganea (Squinabol); Scale bar for all figures = 100
µm. 12 – Becus horridus (Squinabol); Scale bar = 100 µm. 13 –
Pseudoaulophacus sp. aff. P. sculptus (Squinabol); Scale bar = 100
µm. 14 – Pseudoaulophacus sp.; Scale bar = 100 µm. 15 – Alievi-
um sp.; Scale bar = 100 µm. 16 – Patellula sp. aff. P. helios (Squin-
abol); Scale bar = 100 µm. 17 – Dactyliodicus longispinus (Squin-
abol); Scale bar = 100 µm. 18 – Godia concava (Li et Wu); Scale bar
= 200 µm. 19 – Godia lenticulata Jud; Scale bar = 200 µm. 20 –
Godia sp. cf. G. lenticulata Jud; Scale bar = 100 µm. 21 – Dactyl-
iosphaera ex. gr. maxima (Pessagno); Scale bar = 100 µm. 22 – Ar-
chaeospongoprunum salumi Pessagno; Scale bar = 100 µm.
ic Spumellaria/Nassellaria ratio needs additional studies and
cannot be used now for interpretations of Mid-Cretaceous pa-
Spumellaria have some quantitative domination over Nas-
sellaria, but we cannot make any speculations based on such
domination in only one sample. We marked clear quantitative
domination of several species: Archaeocenosphaera? mel-
lifera, Acaeniotyle macrospina, Savaryella quadra, Pyrami-
spongia glascockensis, and Stichomitra communis. The last
species is extremely abundant in all known Cenomanian as-
semblages from the Mediterranean region: Northern Italy
(O’Dogherty 1994), Central Italy (Salvini & Marcucci-Passe-
rini 1998), Southern Spain (O’Dogherty 1994) and Crimea
(Bragina 1999, 2001).
Generally, this assemblage has very close affinity to several
previously studied Cenomanian radiolarian fauna from the
Western Mediterranean (O’Dogherty 1994; Salvini & Marcuc-
ci-Passerini 1998), Crimea (Bragina 1999, 2001) and Atlantic
Ocean (Erbacher 1994). All determined taxa are known from
these regions. Several species (Pyramispongia glascockensis,
Stichomitra communis, Xitus antelopensis, and others) are
known from North America (Pessagno 1976), and they seem
to have very wide (circumtropical) paleogeographical appear-
ance. The studied assemblage is less taxonomically diverse
than coeval assemblages from Italy (O’Dogherty 1994), but
this can be explained by our insufficient knowledge of radi-
olarians from the Ürküt Section that were studied in only one
sample. On the contrary, the assemblage from northern Turkey
is more diverse than the Upper Cenomanian assemblage from
Crimea that consists of only 20 species (Bragina 1999, 2001).
The presence of several well-studied coeval radiolarian as-
semblages correlated with other microfossils, especially with
planktonic Foraminifera (O’Dogherty 1994; Erbacher 1994;
Bragina 2001) provide numerous radiolarian biostratigraphic
data that have to be used in this study. We utilized all well de-
termined species with restricted stratigraphic range for our
biostratigraphic interpretation (Fig. 7), and these data allow us
to determine the age of the studied association. We did not use
taxa determined in open nomenclature, because they need de-
tailed study, description and revision that will be a subject of
The total number of 26 well-determined species were analy-
sed, and their ranges were estimated according to previous
publications on the Cretaceous Radiolaria (Foreman 1975;
Pessagno 1976, 1977; Holzer 1980; Schmidt-Effing 1980;
Thurow 1988; Erbacher 1994; O’Dogherty 1994; Bragina
1999, 2001). We had summarized the previous biostratigraphic
data to show the maximal approximate range for every spe-
cies, and we gave more attention to the well-studied taxa. The
following results were obtained:
1. Large part of analysed taxa (11 species) have their first
appearance in the Middle Albian (Acaeniotyle macrospina,
Archaeocenosphaera? mellifera, Staurosphaeretta wishnio-
vskii, Pessagnobrachia irregularis, Crucella messinae, C. ir-
wini, Savaryella quadra, Acanthocircus impolitus, Archaeod-
ictyomitra sliteri, Stichomitra communis, and Phalangites
telum). Therefore, the studied assemblage is undoubtedly
younger than Early Albian.
356 BRAGIN et al.
THE CENOMANIAN RADIOLARIANS FROM CENTRAL PONTIDES, TURKEY 357
2. Five species (Vitorfus brustolensis, Cavaspongia euga-
nea, Dactyliodiscus longispinus, Xitus antelopensis, and No-
vixitus dengoi) appear for the first time in the Upper Albian.
Therefore, the Middle Albian range can be excluded due to
this lower limit of these well-known taxa.
Fig. 6. Scanning electron micrographs of the radiolarians from the
Devrekani region. 1 – Archaeodictyomitra sliteri Pessagno; Scale
bar = 100 µm. 2—5 – Archaeodictyomitra sp. ex. gr. A. sliteri Pessa-
gno; Scale bar for figure 2, 3 and 5 = 100 µm, figure 4 is detail of
apical part of the figure 3, Scale bar = 40 µm. 6 – Archaeodictyo-
mitra sp. cf. A. squinaboli Pessagno; Scale bar = 40 µm. 7—8 –
Obeliscoites sp. aff. O. turris (Squinabol); Scale bar for figure 7 =
100 µm, figure 8 is detail of medial part of figure 7, Scale bar = 40
µm. 9 – Xitus antelopensis Pessagno; Scale bar = 100 µm. 10 –
Novixitus dengoi Schmidt-Effing; Scale bar = 57 µm. 11—12 – No-
vixitus weyli Schmidt-Effing; Scale bar for figure 11 = 100 µm, fig-
ure 12 is detail of the apical part of figure 11, Scale bar = 40 µm. 13
– Amphipyndax stocki (Campbell et Clark); Scale bar = 100 µm. 14
– Stichomitra sp. ex. gr. S. alamedaensis (Campbell et Clark);
Scale bar = 77 µm. 15—17 – Stichomitra communis Squinabol;
Scale bar for all figures = 100 µm. 18 – Phalangites telum
O’Dogherty; Scale bar = 77 µm. 19—21 – Radiolaria incertae sedis;
Scale bar for all figures = 200 µm.
3. Some of the taxa obtained from the Tomalar Formation
such as Halesium quadratum, H. sexangulum, Archaeospon-
goprunum salumi, and Novixitus weyli appear for the first time
in the Early Cenomanian. So, we can consider that the age of
the assemblage is younger than the Late Albian.
4. The Lower to Middle Cenomanian boundary is marked
by coeval known appearance and extinction of some species. It
is the first appearance level of Patulibracchium woodlanden-
sis and Pyramispongia glascockensis. Another important level
is the boundary between the Middle and Upper Cenomanian.
It represents the last appearance level of Acaeniotyle mac-
rospina, Pessagnobrachia irregularis, Savaryella quadra, and
Becus horridus. The species Staurosphaeretta wisniovskii was
supposed to disappear after the Lower Cenomanian according
to two previous studies (Origlia-Devos 1983; O’Dogherty
1994). Recently, this species was found in the Upper Cenoma-
nian and Lower Turonian strata of Crimea (Bragina 1999,
2001), therefore, it has a wider stratigraphic range than was
5. The Cenomanian-Turonian boundary is characterized by
the last appearance of Hexapyramis pantanellii, Xitus ante-
lopensis, Novixitus dengoi, and N. weyli. According to recent
study of O’Dogherty (1994), two species among analysed fau-
na (Paronaella solanoensis and Mesosaturnalis hueyi) have
Fig. 7. Stratigraphic ranges of the selected radiolarian species from sample 326. The supposed range of Paronaella solanoensis is shown by
dotted line. Grey area indicate the age of assemblage (Cenomanian).
358 BRAGIN et al.
their first appearance level at this boundary. Therefore, we
have again the problem of discordant ranges that should be
Paronaella solanoensis was considered by Erbacher (1994)
and O’Dogherty (1994) as restricted stratigraphically to the
Alievium superbum Zone (lower Turonian). Nevertheless,
Hull (1997) illustrated as Paronaella sp. aff. P. solanoensis
specimens from the Upper Jurassic (Tithonian). These forms
have very close affinity to the Late Cretaceous ones, and Hull
(1997) noted only minor differences. Kiessling (1999) also il-
lustrated similar forms from the Kimmeridgian to Valanginian
of various regions. Bragina (1999, 2001) reported this species
from the Upper Cenomanian of Crimea. Taking into account
the very wide stratigraphic ranges of some radiolarian species
in the Jurassic and Cretaceous (Acaeniotyle umbilicata = late
Oxfordian—early Aptian, Archaeodictyomitra apiarium = Mid-
dle Callovian—Early Aptian, Holocryptocanium barbui = Late
Tithonian—Cenomanian) (Baumgartner et al. 1995), we sup-
pose that Paronaella solanoensis range is not restricted to the
Turonian. It should also be noted that Alievium superbum
(Squinabol), the zone species of the Lower Turonian
(O’Dogherty 1994), is not present in the studied assemblage.
Mesosaturnalis hueyi (= Acanthocircus hueyi in O’Dogherty
1994) was also thought to appear at the Cenomanian-Turonian
boundary. Nevertheless, Foreman (1975) reported this species
from the Albian to Santonian. Forms in this study (Figs. 5.4
and 5.5) possess characteristic features of this species with
wide, massive, and strongly bladed ring. Therefore, Mesosat-
urnalis hueyi has a wider stratigraphic range than was sup-
posed by O’Dogherty (1994).
As a summary, 26 well-determined species are utilized for
biostratigraphic datation. It can be concluded that the age of
the studied assemblage is Cenomanian. The most probable re-
stricted range of assemblage is the middle Cenomanian due to
the fact that several species of our assemblage have presently
known first appearance levels at the early-middle Cenomanian
boundary, as well as some species which seem to be extinct at
the beginning of the late Cenomanian. All common and typi-
cal Cenomanian taxa are present in the studied assemblage.
The only exception is Pseudodictyomitra pseudomacrocepha-
la (Squinabol), characteristic species of the Albian—Turonian
interval, which is not present in studied assemblage. We ex-
pect to find this species during further studies. For example,
Pseudodictyomitra pseudomacrocephala is very rare in the
Upper Cenomanian of Crimea (Bragina 1999, 2001), and is
probably, rare in the studied assemblage too.
The assemblage from Ürküt Section can be correlated with
assemblages of Dactyliosphaera silviae Zone (Radiolaria) of
the Cenomanian from Italy and Spain (O’Dogherty 1994).
This radiolarian zone ranging from the middle part of Lower
Cenomanian to the lowermost part of Upper Cenomanian has
good correlation with ammonite and foraminiferal zonal suc-
cessions. The Dactyliosphaera silviae Zone is correlative with
ammonite zones Mantelliceras dixoni (upper part), Alternoa-
canthoceras rhotomagense, and A. jukesbrownei. It could also
be correlated with foraminiferal zones Rhotalipora brotzeni,
R. reicheli, and R. cushmani.
The radiolarian assemblage from the lower part of the
Tomalar Formation has the Cenomanian (possibly middle
Cenomanian) age. It has close affinity with coeval assemblag-
es of the Western Mediterranean and Atlantic Ocean and re-
flects the conditions of an open marine basin. This affinity
provides a good opportunity to apply the previously defined
zonal scales of the Mid-Cretaceous (Erbacher 1994;
O’Dogherty 1994) in the Eastern Mediterranean area. The
stratigraphic range of the Tomalar Formation probably covers
the interval from Cenomanian to Maastrichtian.
Further studies should be concerned with detailed sampling
of radiolarian-bearing lithologies from the Tomalar Formation,
taxonomic description of the Cenomanian Radiolaria and on
their biostratigraphic calibration by using other microfossils
(planktonic Foraminifera and nannofossils).
Acknowledgments: The authors greatly appreciate Prof. Dr.
C. Göncüoglu (Middle East Technical University, Ankara) for
his kind reviewing of the manuscript and Günül Atay (MTA,
Ankara) for technical support during preparation of work. Au-
thors express their thanks for Nina Gorkova (Geological Insti-
tute, Moscow) for studies on SEM. This work was partly sup-
ported by the Russian Foundation for Fundamental Studies
(Grants 00-05-64018 and 00-05-64298).
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