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GEOLOGICA CARPATHICA, AUGUST 2007, 58, 4, 305—320

www.geologicacarpathica.sk

Introduction

Well-preserved radiolarians have been discovered in the
Jurassic siliceous sediments of the Bucegi Massif and Pi-
atra Craiului Mts (Southern Carpathians, Romania), and
the investigated sections are the most representative Juras-
sic outcrops for that area. During the Jurassic time, this re-
gion of the Carpathian chain was characterized by basins
and narrow sectors of platform. The studied successions
contain a large amount of siliciclastic admixture. The lay-
ers sampled for radiolarians are well stratified siliceous
limestone and radiolarian chert whose thickness usually
ranges between 0.5 and 1 m.

Radiolarian faunas from the Romanian Carpathians

have been previously studied by Dumitrica (1970, 1991,
1995a,b), Dumitrica & Dumitrica-Jud (1995, 2005) and
Dumitrica  & Carter (1999). Dumitrica also examined the
fauna from the Bucegi Massif and Piatra Craiului Mts for
describing the new genus Pterotrabs (Dumitrica et al.
1997) and the internal structure of some Radiolaria (Dumi-
trica 1999). So far, no biostratigraphical analyses of radi-
olarian assemblages have been published for the studied
sections in the Bucegi Massif and Piatra Craiului Mts.

Previous researches concerning the geology and the pale-

ontology of the Mesozoic deposits in the investigated out-
crops of the Bucegi Massif and Piatra Craiului Mts were
accomplished by Herbich (1888), Jekelius (1916, 1928,

Oxfordian and Callovian radiolarians from the Bucegi Massif

and Piatra Craiului Mountains (Southern Carpathians,

Romania)

PAOLA BECCARO

1

 and IULIANA LAZĂR

2

1

Universit

à degli Studi di Torino, Dipartimento di Scienze della Terra, Via Valperga Caluso 35, 10125 Torino, Italy;  paola.beccaro@unito.it

2

University of Bucharest, Faculty of Geology and Geophysics, N. Balcescu Ave., RO-010041 Bucharest, Romania;  iul_lazar@yahoo.com

(Manuscript received August 10, 2006; accepted in revised form December 7, 2006)

Abstract: This paper regards the description and the first dating of the radiolarian assemblages of the Jurassic siliceous
successions in the Bucegi and Piatra Craiului Mts (Southern Carpathians, Romania). The most representative Jurassic
outcrops for this area have been sampled: La Poli ie, Strunga, Strunguli a, Rătei Valley and Sfânta Ana Olistolith (Bucegi
Massif), and  irnea, Umeri and Vladu ca (Piatra Craiului Mts). The investigated successions are formed by a great variety
of sediments, most of them characterized by a large amount of siliciclastic admixture. The sampled layers are constituted by
well stratified siliceous limestone or chert, and their thickness usually ranges between 0.5 and 1 m. The Sfânta Ana sample
comes from a Jurassic olistolith included in a Lower Cretaceous flysch. The Nassellaria/Spumellaria and sponge spicules/
radiolarians ratios provided information about the depositional environments. In well-preserved samples the N/S ratio
varies from 1.7 to 2.8, and the spicules/radiolarians ratio is around 0.6: this means that the siliceous sediments were deposited
in distal or relatively deep waters. The biostratigraphical analysis has been carried out by applying two radiolarian zonations
based on the Unitary Associations method: most samples are referred to the middle-late Oxfordian. The only exception is
represented by the Rătei sample that is assigned to the Callovian. The Romanian successions are easily comparable with other
Tethyan sections where the Oxfordian levels are generally the richest in radiolarians. Even in environments with siliciclastic
supply (Southern Carpathians) the sedimentation drastically changed during the Oxfordian and became siliceous.

Key words: Jurassic, Southern Carpathians, Romania, biostratigraphy, siliceous sediments, micropaleontology,
radiolarians, Unitary Associations Zones.

1938), Oncescu (1943), Patrulius (1957, 1962, 1969), Pope-
scu (1966), Lazăr (2000, 2004), Lazăr & Barbu (2004).

This paper represents the first attempt to date the South-

ern Carpathians siliceous sediments directly by radiolari-
ans. The purposes are to provide the description of the
radiolarian assemblages of the Bucegi and Piatra Craiului
sections (also considering the preservation status, and the
Nassellaria/Spumellaria and spicules/radiolarians ratios),
to date the studied successions by two radiolarian zona-
tions (Baumgartner et al. 1995a and Beccaro 2006) and to
compare the studied siliceous facies with coeval Tethyan
facies. An overview on Carpathian siliceous sediments
outside Romania is also given.

Geological setting

The Bucegi Massif and Piatra Craiului Mts are located in

the eastern end of the Southern Carpathians in the junction
area between the structural units of the Eastern and South-
ern Carpathians (Fig. 1). From the paleogeographical view-
point the Bucegi Massif and Piatra Craiului Mts belong to
the Getic Carbonate Platform. Triassic deposits lie trans-
gressively on the pre-Alpine crystalline basement and the
Jurassic sedimentation started with continental deposits
(conglomerate, sandstone, bituminous clay) (Patrulius et al.
1980). During the Middle Jurassic, narrow faulted shelves

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BECCARO and LAZĂR

with siliciclastic and carbonate deposits developed. Be-
tween these sediments, a continuous unit of radiolarites can
be identified at the top of a condensed sequence (sometimes
displaying mineralized hardgrounds). During the Late Ju-
rassic, carbonate sedimentation became more widespread
with the deposition of pelagic limestone (micrite contain-
ing ammonites alternated with siliceous levels). In the Early
Cretaceous, differential block-tilting drowned some parts of
the former Getic Platform while other parts emerged: deep
water sedimentation was contemporaneous with some patch
reefs and karstification processes (Patrulius et al. 1980). Ter-
tiary deposits are mainly siliciclastics and occur only spo-
radically in this sector of the Southern Carpathians.

The Bucegi Massif contains several olistoliths which

are embedded in the Piscul cu Brazi Formation, a Lower
Cretaceous (Barremian—Aptian) flysch constituted by con-
glomerate, sandstones, siltstones and marls (Patrulius
1969). One of these olistoliths is the Sfânta  Ana Olistolith:
it is Middle-Late Jurassic in age and has been sampled for
this research.

Geographical location and lithological description

of the sections

Stratigraphical sections at the Bucegi Massif

The location of the sections in the Bucegi Massif

(Southern Carpathians, Romania) are shown in the Fig. 1.
From North to South, the outcrops are: La Poli ie Saddle,

Strunga Pass, Strunguli a Pass, Rătei Valley, Sfânta Ana
Olistolith (Pele  Valley). The stratigraphical logs are illus-
trated in Fig. 2. The ages of the siliceous levels are based
on the radiolarian data that will be subsequently discussed
in detail (see chapter regarding the radiolarian biostratig-
raphy).

La Poli ie Saddle is situated in the northern extremity

of the Bucegi Massif at approximately 1730 m in altitude.
The sedimentary rocks are represented by Middle-Upper
Jurassic and Lower Cretaceous deposits with a total thick-
ness of around 150 m. The complete succession can be
seen only by the junction of the outcrops of the La Poli ie
Saddle, Gaura Valley and of the small trail between these
two locations. The succession cropping out at La Poli ie
Saddle is illustrated in Fig. 2a. In the lower part of the sec-
tion there are siliceous limestones (1—1.3 m the visible
thickness), where the studied samples come from; the age
of the upper part of such limestones is referred to middle-
late Oxfordian by radiolarians. The Kimmeridgian-lower
Tithonian deposits are represented by reddish-green lime-
stone (sometimes nodular) with poorly preserved ammo-
nites in the lower part (Jekelius 1916; Patrulius 1969) and
fine granular white limestone in the upper part of the sec-
tion. The Bajocian-Bathonian deposits (3 m thick), repre-
sented by calcareous sandstone and bioclastic calcarenites
alternating with thin sandy levels can be observed on a
small right affluent of the Gaura Valley. This outcrop was
described in detail by Lazăr & Barbu (2004), and bivalves,
brachiopods, rare gastropods and echinoids were collected
from the sandstones.

Fig. 1. Geological sketch map of the studied area (Southern Carpathians, Romania) and the geographical location of the stratigraphical sections at
the Piatra Craiului Mts (1 – Vladu ca, 2 – Umeri, 3 –  irnea) and in the Bucegi Massif (4 – La Poli ie, 5 – Strunga, 6 – Strunguli a,
7 – Rătei, 8 – Sfânta Ana).

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OXFORDIAN AND CALLOVIAN RADIOLARIANS (SOUTHERN CARPATHIANS, ROMANIA)

Sfânta Ana Olistolith is located in the Pele  Valley

(eastern flank of the Bucegi Massif) near Sinaia, at about
1110 m altitude. The stratigraphical log of this area is il-
lustrated in the Fig. 2b. The olistolith is constituted by
Middle-Upper Jurassic siliciclastic and carbonate depos-
its, and it is included within Barremian-Aptian conglomer-
ates. The Bathonian-lower Callovian deposits are
represented by calcareous sandstone alternating with silts,
marls and biocalcarenites with poorly preserved macrofauna
(ammonites, aptychi, belemnites, bivalves, rare brachio-

pods). The siliceous limestones are 1 m thick and are re-
ferred to the middle Oxfordian by radiolarians. They are
followed by grey massive nodular limestone Kimmerid-
gian in age.

At the Strunga Pass (1904 m altitude) and Strunguli a

Pass-Tataru Peak (1998 m altitude) the most typical sec-
tion for the Jurassic of the Getic Nappe sedimentary cover
can be observed. The stratigraphical log of this area is
shown in the Fig. 2c. Quartzitic conglomerates, calcareni-
tes, argillaceous silts, biocalcarenites and calcareous sand-

Fig. 2. Stratigraphical columns of the La Poli ie (a), Sfânta Ana (b) and Strunga—Strunguli a (c) sections (Bucegi Massif, Southern Car-
pathians, Romania). The Sfânta Ana succession is a Jurassic olistolith included in the Lower Cretaceous flysch. On the left of the logs
are reported the ranges: the ages in bold are based on radiolarians (this paper) and ammonites (Patrulius 1969; Mutihac & Ionesi 1973),
the other ages are only hypothesized in the literature. The arrows indicate the position of the samples; LaP 1 and LaP 2 come from the
same layer; “S” refers to the Strunga sample and “s” to the Strunguli a sample.

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BECCARO and LAZĂR

stone mainly represent the lower part of the succession.
From these deposits, Lazăr (2000, 2002, 2004) described
numerous species of bivalves. From the top of the silici-
clastic sediments Patrulius (1969) described ammonite as-
sociations that refer to early Bathonian (Zigzag Zone),
early late Bathonian (Retrocostatum Zone) and late Ba-
thonian (Aspidoides and Discus Zones). The successive
sediments are constituted by reddish siliceous marls and
jasper less than 1 m thick and assigned to Oxfordian by ra-
diolarians. The jasper is topped by nodular limestones rich
in ammonites: Patrulius (1969) described a good ammo-
nites assemblage that refers the sediments to the Kim-
meridgian-Tithonian. Mutihac & Ionesi (1973) reported
an  Aspidoceras acanthicum ammonite fauna that refers to
the upper part of the lower Kimmeridgian.

The  Rătei Valley is a right side tributary of the Ialomita

Valley on the western flank of the Bucegi Massif. The suc-
cession is similar to Strunga—Strunguli a section and, due
to poor exposure, the stratigraphical column is not illus-
trated. In the Rătei Valley, quartzitic conglomerate, calcar-
eous sandstone and calcarenites occur, and the total
thickness of these deposits is much smaller than at Strun-
ga—Strunguli a (where it exceeds 40 m). In the Rătei Val-
ley, owing to the scanty exposure of the outcrops, the
stratigraphical position of the sediments is questionable.
Patrulius (1969) assumed that the middle-upper Callovian
is represented by grey and green jasper, and that the pres-
ence of the Oxfordian is limited to resedimented clasts in
the Kimmeridgian limestone. The samples for radiolarians
were collected from a thin (0.1 m thick) Callovian jasper
at the top of the Bajocian-Bathonian sandstones.

Stratigraphical sections at the Piatra Craiului Mts

In the Piatra Craiului Mts (Southern Carpathians, Roma-

nia) three stratigraphical sections have been studied:
Vladu ca, Umeri and  irnea (Fig. 1). The most continuous
and well developed Middle Jurassic deposits of the Piatra
Craiului Mts are exposed in the Vladu ca Valley and a
synthetic log from this locality is illustrated for all three
sections (Fig. 3). The ages of the siliceous levels are based
on the radiolarian data that will be subsequently discussed
in detail (see chapter regarding the radiolarian biostratig-
raphy).

The  Vladu ca  section is located in the upper part of the

Vladu ca Valley, a few kilometers northwest of Umeri. Over
the metamorphic basement, a succession composed of basal
conglomerates and graywackes/sandstones occurs, fol-
lowed by a thick sandstone/siltstone unit containing mol-
luscs. The radiolarites occur at the top of the siliciclastic
sequence. Bucur (1980) described some radiolarians in thin
sections and assumed a Bajocian to Oxfordian age. On the
basis of new radiolarian data (this paper) the siliceous sedi-
ments are assigned to middle-late Oxfordian.

The  Umeri section is situated in the upper part of Bârsa

Tăma ului Valley at 1600 m in altitude, along the foot-
path from the base of the limestone cliffs of Piatra Craiului
Mts. Here, the entire Jurassic succession crops out, starting
with thin microconglomerates overlying the metamorphic

basement, and then followed by sandstones and siltstones.
The radiolarites occur as thin beds (1—1.5 m in total thick-
ness) with transitional lower and upper boundaries to-
wards bioclastic red limestones. The siliceous sediments
are dated by radiolarians as middle-late Oxfordian, and are
followed by up to 900 m of shallow-water Kimmeridgian-
Tithonian limestones.

The  irnea section is located in the area between the

Bucegi Massif and Piatra Craiului Mts. Here, the Middle
Jurassic deposits are very thin (5—10 m) and lie directly on
the metamorphic basement. The base of the Jurassic suc-
cession is composed of sandstones which rapidly pass into
sandy oolitic limestone and marls. The radiolarites occur
as nodular beds in the red mudstone, and are middle Ox-
fordian in age (this paper). White massive Kimmeridgian
limestone follows the siliceous deposits.

Methods

The laboratory treatments followed the standard meth-

ods using hydrochloric acid first, and hydrofluoric acid af-
terwards (Dumitrica 1970; Pessagno & Newport 1972; De
Wever 1982; De Wever et al. 2001).

The following indices have been estimated: Preservation

Index (PI), Nassellaria/Spumellaria ratio (N/S), and sponge
spicules/radiolarians ratio. The PI evaluates the preserva-
tion status of the radiolarians: it ranges from 1 (excellent) to 8

Fig. 3. Stratigraphical column of the Vladu ca section (Piatra Craiului
Mts, Southern Carpathians, Romania). The most continuous and well
developed Middle Jurassic deposits of the Piatra Craiului Mts are ex-
posed in the Vladu ca Valley and this log (redrawn after Bucur
1980) is representative also for the  irnea and Umeri sections. The
ages defined in this research by radiolarians are indicated in bold.

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OXFORDIAN AND CALLOVIAN RADIOLARIANS (SOUTHERN CARPATHIANS, ROMANIA)

(extremely poor), and refers to recrystallization and corro-
sion but not to fragmentation (Kiessling 1996).

The biostratigraphical analysis has been carried out by

applying the radiolarian zonations of Baumgartner et al.
(1995a) and Beccaro (2006). The zonation UAZ95 of
Baumgartner et al. (1995a) refers to a world correlation
for the Middle Jurassic—Early Cretaceous Tethyan Realm
and spans the Aalenian to early Aptian time through 22
UAZones. The database of the UAZ95 contains more
than 160 stratigraphical sections: the sacrifice of vertical
resolution was unavoidable and the ranges expressed by
the UAZ95 are quite long. The zonation UAZ-SA of
Beccaro (2006) refers to the Unitary Association Zones
defined for Sicily and the Southern Alps (Italy). The
database of the UAZ-SA contains the stratigraphical
distributions of the radiolarians in 9 Italian sections: it
provides a more precise vertical resolution but a more lo-
cal zonation in comparison with Baumgartner et al.
(1995a). The zonation of Beccaro (2006) ranges from ear-
ly Bathonian to late Kimmeridgian through 6 UAZones.

Some considerations about radiolarian and spicule

abundances

The ratios Nassellaria/Spumellaria (N/S) and sponge spi-

cules/radiolarians are well known to have a high paleoeco-
logical potential: they provide a significant tool for
determining the distance from the shelf and suggesting fluc-
tuations in sea level (Casey 1993). The N/S is positively
correlated with the bathymetry: Nassellaria increase in rela-
tive abundance in deeper water sediments or at great dis-
tance from the shelf (N/S is very high in distal basins and
around one in open oceanic plateaux or proximal slopes)
while Spumellaria dominate in shallow waters (Kiessling
1996). The morphological diversity of the species is also
positively correlated with the bathymetry: the number and
diversity of species in oceanic sediments are much higher
than in coastal sediments (Kruglikova 1989). On the con-
trary, the relative abundance of sponge spicules is inversely
correlated with bathymetry: the spicules only make a signif-
icant contribution to the siliceous microfossil content in
slope or proximal environment sediments, especially those
with a high turbiditic influence (Kiessling 1996). Neverthe-
less, before any paleoenvironmental considerations, we
must consider the role of the preservation status on the fau-
nal ratios. Sponge spicules have a higher preservation po-
tential in comparison with radiolarians and high spicule
abundance in poorly preserved material has a very limited
paleoecological meaning (Kiessling 1996).

In the samples of the Bucegi and Piatra Craiului sec-

tions (Southern Carpathians, Romania), an evaluation of
the faunal ratios based on 300 specimens has been provid-
ed in order to get some information about the relative
abundance of radiolarians and sponge spicules, and after-
wards on the depositional environments. The preservation
status is indicated by the Preservation Index (PI) as de-
scribed by Kiessling (1996). The N/S and spicules/radi-
olarians ratios, and the PI are reported in the Figs. 4—5.

In most samples Nassellaria are more abundant than

Spumellaria and the spicules/radiolarians ratio is close to
1: these data suggest the deposition in distal or relatively
deep waters. Especially the assemblages of La Poli ie
(Bucegi Massif) and Umeri  (Piatra Craiului Mts) are the
most reliable thanks to their good preservation (PI ranging
2 to 4). In Strunga and Strunguli a (Bucegi Massif) and
Vladu ca (Piatra Craiului Mts) assemblages, the preserva-
tion is poor and the ratios among Nassellaria, Spumellaria
and spicules probably do not reflect the primary composi-
tion of the thanatocoenosis.

The radiolarian assemblage of Sfânta Ana (Bucegi Mas-

sif) indicates the deposition in proximal waters or slope
environment due to the abundant occurrence of Spumel-
laria and sponge spicules. Amongst the studied samples,
this radiolarian assemblage is the only one in which
Spumellaria clearly dominate over Nassellaria (N/S = 0.3)
and the spicules represent 60 % of the siliceous content.
The preservation is generally moderate (PI = 4) and most of
the smallest radiolarians are well preserved (PI = 3).

In the Rătei  sample (Bucegi Massif) Nassellaria strongly

dominate over Spumellaria (N/S is around 9) and the spi-
cules/radiolarians ratio is close to 1. Even though the pres-
ervation is poor (PI = 6), these data could be reliable
because the spicules (whose preservation potential is higher
than radiolarians) do not dominate the assemblage and the
Nassellaria are indeed more abundant than Spumellaria. It is
reasonable to suppose that the Rătei sediments were depos-
ited in distal or relatively deep environments.

The paleoenvironmental considerations based on the N/S

and the spicules/radiolarians ratios agree well with the
geological setting of the studied sections: during Middle
and Late Jurassic the siliceous sediments were deposited
on fragments of the former carbonate platform located in
different environments (proximal and distal waters).

Radiolarian biostratigraphy of the Bucegi Massif

and Piatra Craiului Mountains

The radiolarian assemblages of nine samples from eight

sections of the Bucegi Massif (La Poli ie Saddle, Strunga
Pass, Strunguli a Pass, Rătei Valley and Sfânta Ana Olis-
tolith) and Piatra Craiului Mts (Vladu ca, Umeri,  irnea)
have been studied. Most of the samples are rich in taxa:
the lists of species are reported in the Figs. 4—5.

Each taxon is marked by a code: the species carrying a

numerical code are illustrated in the catalogue of Baum-
gartner et al. (1995b) and used for building the UAZ95
biozonation (Baumgartner et al. 1995a); the species carry-
ing a lettered code were only used in the UAZ-SA biozo-
nation (Beccaro 2006); the species marked with an
asterisk were not used for building the UAZ-SA zonation.

The stratigraphical distributions of Eucyrtidiellum  unu-

maense s.l. (Yao) and Williriedellum (?) marcucciae Corte-
se were stated to end in UAZ 8 (middle Callovian-early
Oxfordian) by Baumgartner et al. (1995a) and these taxa
have been proved to continue up to middle Oxfordian
(Beccaro 2004). The biostratigraphical value of some spe-

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BECCARO and LAZĂR

Fig. 4. Stratigraphical distribution of radiolarian taxa in the Bucegi Massif sections (Southern Carpathians, Romania). The species carrying
a numerical code are illustrated in Baumgartner et al. (1995b); the species carrying a lettered code are not included in that volume; taxa
carrying an asterisk have not been used for building the UAZ-SA zonation of Beccaro (2006). The black square indicates the occurrence
of a group of species for biostratigraphical purposes. The ages of the samples are given by the Unitary Association Zones of Baumgartner
et al. (1995a) (UAZ95) and by the Unitary Association Zones for Sicily and the Southern Alps (Italy) of Beccaro (2006) (UAZ-SA). The
Preservation Index ranges from 3 (good) to 7 (very poor) (Kiessling 1996).   Continued on next page.

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OXFORDIAN AND CALLOVIAN RADIOLARIANS (SOUTHERN CARPATHIANS, ROMANIA)

cies (*Gorgansium spp. sensu Baumgartner et al. (1995b),
*Higumastra  wintereri Baumgartner et Kito, Tethysetta
dhimenaensis  ssp. A sensu Baumgartner et al. (1995b),
Zhamoidellum (?) exquisitum Hull) are still questionable
because of their sparse occurrence, and it is likely that
their ranges are slightly different from what is stated in
Baumgartner et al. (1995a). The stratigraphical distribu-
tions expressed by UAZ-SA for some species (Cingulotur-
ris  carpatica Dumitrica, Homoeoparonaella  argolidensis
Baumgartner,  Loopus primitivus (Matsuoka et Yao), Miri-
fusus dianae dianae (Karrer), Napora lospensis Pessagno,
Triactoma 

blakei (Pessagno), Tritrabs 

rhododactylus

Baumgartner) are not in disagreement with other taxa of
the same assemblage because it is known from other sec-
tions (Baumgartner et al. 1995a) that they have longer
ranges than those expressed by the UAZ-SA. For building
the UAZ-SA zonation, the species *Palinandromeda pod-
bielensis (Ožvoldová) was included under “Palinandrome-
da  spp.”, which refers to a group of Palinandromeda
Pessagno, Blome et Hull  in order to give a biostratigraphi-
cal potential also to those species  that are easily recogniz-
able but show low frequency along the sections (Beccaro
2006).

Hexasaturnalis nakasekoi Dumitrica et Dumitrica-Jud

was included under Hexasaturnalis suboblongus (Yao) at
the time of the UAZ95 (Baumgartner et al. 1995a). Recent-
ly,  H. suboblongus (Yao) has been split in two species: H.
suboblongus  (Yao) and H. nakasekoi Dumitrica et Dumi-
trica-Jud  (Dumitrica & Dumitrica-Jud 2005). Dumitrica et
Dumitrica-Jud (2005) assert that H. suboblongus spans the
Bajocian and H. nakasekoi ranges within the Bathonian—
Kimmeridgian interval.

Below follow the description of the radiolarian assem-

blages and the biostratigraphical considerations for each
sample.

La Poli ie (Bucegi Massif) – The samples LaP 1 and

LaP 2 have been collected from the same layer at the La
Poli ie section. By applying the UAZ95 zonation, the age
of the layer seems assignable to UAZ 10 (late Oxfordian-
early Kimmeridgian) for the presence of Emiluvia  ultima
Baumgartner et Dumitrica (UAZ 10—11; Fig. 6.20), Emilu-
via  premyogii Baumgartner (UAZ 3—10) (Fig. 6.21),
Gongylothorax  favosus Dumitrica (UAZ 8—10) and Tri-
trabs  casmaliaensis (Pessagno) (UAZ 4—10; Fig. 6.10).
The age of LaP 1 also includes UAZ 9 (middle—late Oxfor-
dian) by *Emiluvia nana Baumgartner (UAZ 6—9), *Pali-
nandromeda podbielensis (Ožvoldová) (UAZ 5—9), and
*Triactoma  mexicana Pessagno et Yang (UAZ 5—9). By
means of UAZ-SA zonation, the age of the layer is referred
to UAZ E (?late Oxfordian-early Kimmeridgian pars)
thanks to the occurrence of Emiluvia  ultima Baumgartner
et Dumitrica (UAZ E—F), Emiluvia  premyogii Baumgartner
(UAZ A—E), Perispyridium ordinarium gr. (Pessagno)
(UAZ A—E; Fig. 6.7), Tetratrabs zealis (Ožvoldová) (UAZ
B—E) and Williriedellum carpathicum Dumitrica (UAZ
B—E). The age of LaP 1 also includes UAZ D (?middle—
?late Oxfordian) for the presence of Palinandromeda spp.
(UAZ A—D), Podobursa polyacantha (Fischli) (UAZ A—D),
Triactoma enzoi Beccaro (UAZ B—D). The genus Palinan-
dromeda is a good marker for the Oxfordian (UAZ 9 and
UAZ D) and only Emiluvia  ultima Baumgartner et Dumi-
trica goes up to late Oxfordian-early Kimmeridgian (UAZ
10 and UAZ E). Furthermore, some species typically asso-
ciated with E.  ultima (such as Acaeniotyle umbilicata

Fig. 4. Continued from previous page.

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BECCARO and LAZĂR

Fig. 5. Stratigraphical distribution of radiolarian taxa in the Piatra Craiului sections (Southern Carpathians, Romania). The species carrying
a numerical code are illustrated in Baumgartner et al. (1995b); the species carrying a letter code are not included in that volume; taxa car-
rying an asterisk have not been used for building the UAZ-SA zonation of Beccaro (2006). The ages of the samples are given by the Uni-
tary Association Zones of Baumgartner et al. (1995a) (UAZ95) and by the Unitary Association Zones for Sicily and the Southern Alps
(Italy) of Beccaro (2006) (UAZ-SA). The Preservation Index ranges from 2 (very good) to 5 (moderate) (Kiessling 1996).

Fig. 6. Upper Jurassic radiolarians from the Bucegi Massif (Southern Carpathians, Romania). The samples LaP 1 and LaP 2  come from the
same layer of the La Poli ie section. The species carrying an asterisk have not been used for building the UAZ-SA zonation (Beccaro 2006).
The scale bar A corresponds to 200  m for photos at  100 and to 100  m for photos at  200; the scale bar B corresponds to 100  m for im-
ages at  150 and to 50  m for images at  300. 1 – *Archaeospongoprunum elegans Wu, LaP 1,  150; 2 – *Archaeospongoprunum sp. aff.
A. elegans Wu,  LaP 2,  150;  3 – *Pantanellium josephinense Pessagno, Blome et Hull,  LaP 2,  150;  4 – *Archaeospongoprunum  imlayi
Pessagno, LaP 1,  150; 5 – Triactoma blakei (Pessagno), LaP 1,  100; 6 – *Gorgansium spp., LaP 1,  300; 7 – Perispyridium ordinarium
(Pessagno) gr., LaP 2,  100;  8 – *Praeconocaryomma sp., LaP 2,  100;    9 – *Higumastra  wintereri Baumgartner et Kito, LaP 1,  150;

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OXFORDIAN AND CALLOVIAN RADIOLARIANS (SOUTHERN CARPATHIANS, ROMANIA)

Fig. 6. 

Continued  from previous page.

  10 – Tritrabs casmaliaensis (Pessagno), LaP 2,  150;  11 – Tritrabs  rhododactylus  Baumgartner,

LaP 2,  100;  12 – Tritrabs exotica (Pessagno), LaP 1,  100;  13 – Angulobracchia  biordinalis Ožvoldová, LaP 2,  100;  14 – *Tritrabid
gen. et sp. indet., LaP 2,  150; 15 – *Paronaella mulleri Pessagno, LaP 1,  150; 16 – *Tetraditryma emilei Hull, LaP 2,  150; 17 – Emilu-
via peteri Beccaro, LaP 1,  150;  18  –  *Emiluvia sedecimporata (Rüst),  LaP 2,  150;  19 – Emiluvia hopsoni Pessagno, LaP 1,  150;
20 – Emiluvia ultima Baumgartner et Dumitrica, LaP 2,  100; 21 – Emiluvia premyogii Baumgartner, LaP 2,  150; 22 – *Haliodictya (?)
hojnosi  Riedel et Sanfilippo, LaP 1,  200;  23 – *Pseudocrucella sanfilippoae (Pessagno), LaP 2,  150;  24 – Podobursa spinosa
(Ožvoldová), LaP 2,  150;  25 – Podobursa vannae Beccaro, LaP 1,  150;  26 – Napora deweveri Baumgartner,  LaP 1,  150;  27 – Loo-
pus doliolum Dumitrica, LaP 1,  300; 28 – Eucyrtidiellum ptyctum (Riedel et Sanfilippo), LaP 1,  200; 29 – Parahsuum carpathicum Widz
et De Wever, LaP 2,  150;    30  –  Protunuma japonicus Matsuoka et Yao, LaP 2,  200;  31 – Tethysetta  dhimenaensis ssp. A sensu
Baumgartner et al. 1995b, LaP 2,  200; 32 – Zhamoidellum ovum Dumitrica, LaP 1,  200; 33 – Zhamoidellum (?) exquisitum Hull, LaP 1,

200; 34 – *Stichocapsa tuscanica Chiari, Cortese et Marcucci, LaP 1,  300; 35 – *Williriedellum crystallinum Dumitrica, LaP 1,  300.

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BECCARO and LAZĂR

Fig. 7. Middle-Upper Jurassic radiolarians from the Bucegi Massif (Southern Carpathians, Romania). The taxa illustrated come from
the Strunguli a, Sf. Ana and Rătei sections. The species carrying an asterisk have not been used for building the UAZ-SA zonation
(Beccaro 2006). The scale bar A corresponds to 200  m for photos at  100 and to 100  m for photos at  200; the scale bar B
corresponds to 400  m for images at  75, to 100  m for images at  150 and to 50  m for images at  300; the scale bar C corresponds to
100  m for photos at  250. 1 – Tetratrabs bulbosa Baumgartner, Strunguli a,  75; 2 – Emiluvia orea Baumgartner, Strunguli a,  100;
3 – *Emiluvia nana Baumgartner, Strunguli a,  150; 4 – Homoeoparonaella argolidensis Baumgartner, Sf. Ana,  100; 5 – *Triactoma
mexicana Pessagno et Yang, Strunguli a,  100;  6  – Hexasaturnalis minor (Baumgartner), Strunguli a,  100;  7  – Hexasaturnalis
nakasekoi Dumitrica et Dumitrica-Jud, Strunguli a,  100;  8  –  *Tripocyclia brooksi Pessagno et Yang, Sf. Ana,  100;  9  – Triactoma
enzoi Beccaro, Sf. Ana,  100;  10  – Dicerosaturnalis angustus (Baumgartner),  Strunguli a,  100;  11  – *Paronaella sp. aff. P.
bandyi Pessagno, Sf. Ana,  150; 12 – *Eospongosaturnalis protoformis (Yao), Rătei,  100; 13 – *Acanthocircus sp., Strunguli a,  100;
14 – Bernoullius dicera (Baumgartner), Sf. Ana,  150. 15 – *Pterotrabs victoria Dumitrica, Baumgartner et Goričan, Strunguli a,  150.

(Rüst),  Podocapsa amphitreptera Foreman, Syringocapsa
spinellifera Baumgartner) are absent. It could be possible
that La Poli ie samples are not restricted to UAZ 10 and
UAZ E (as E. ultima seems to indicate) but extended to
middle Oxfordian (UAZ 9 and UAZ D), as suggested by
many species occurring in LaP 1.

Strunga  (Bucegi Massif) – Through the UAZ95 zona-

tion, the radiolarian assemblage is referred to UAZ 5—8
(latest Bajocian—early Bathonian to middle Callovian—
early Oxfordian) for the presence of *Triactoma mexicana
Pessagno et Yang (UAZ 5—9) and Eucyrtidiellum  unu-
maense s.l. (Yao) (UAZ 3—8). By applying the UAZ-SA zo-
nation, the age spans UAZ C (middle Oxfordian) due to
Eucyrtidiellum  unumaense s.l. (Yao) (UAZ A—C) and Tri-
actoma blakei (Pessagno) (UAZ C—F). The sample can be
referred to middle Oxfordian.

Strunguli a  (Bucegi Massif) – By way of UAZ95 zona-

tion, the age is referred to UAZ 8—9 (middle Callovian—
early Oxfordian to middle—late Oxfordian) by the presence
of  Archaeodictyomitra  apiarium (Rüst) (UAZ 8—22), Emi-
luvia  orea Baumgartner (UAZ 8—11; Fig. 7.2), Podobursa
spinosa  (Ožvoldová) (UAZ 8—13), *Emiluvia  nana Baum-
gartner (UAZ 6—9; Fig. 7.3), *Palinandromeda  podbielen-
sis (Ožvoldová) (UAZ 5—9; Fig. 7.19) and *Triactoma
mexicana Pessagno et Yang (UAZ 5—9; Fig. 7.5). Through
the UAZ-SA zonation, the age of the sample is constricted
to UAZ D (?middle—?late Oxfordian) due to Archaeodicty-
omitra apiarium (Rüst) (UAZ D—F), Tetratrabs bulbosa
Baumgartner (UAZ D—F; Fig. 7.1), Palinandromeda  spp.
(UAZ D). The sample is assigned to middle-late Oxfordian.

Rătei  (Bucegi Massif) –  Through the UAZ95 zonation,

the sample is assigned to UAZ 7 (late Bathonian—early
Callovian) by the presence of Cinguloturris  carpatica
Dumitrica (UAZ 7—11), Williriedellum  carpathicum Dumi-
trica (UAZ 7—11; Fig. 7.33) and *Stichocapsa naradanien-
sis Matsuoka (UAZ 6—7; Fig. 7.31). By way of UAZ-SA zo-
nation, the assemblage dates from the UAZ B—C (early
Callovian  pars—early Oxfordian to middle Oxfordian)
thanks to Dicerosaturnalis angustus (Baumgartner) (UAZ
B—E), Triactoma enzoi Beccaro (UAZ B—D), Williriedel-
lum carpathicum Dumitrica (UAZ B—E), Eucyrtidiellum
unumaense s.l. (Yao) (UAZ A—C) and Williriedellum  (?)
marcucciae Cortese (UAZ B—C). Considering that *Sti-
chocapsa naradaniensis Matsuoka is a good marker for
the Callovian time and that no species quite typical of Ox-
fordian age (like Gongylothorax  favosus Dumitrica and
*Williriedellum  crystallinum Dumitrica) have been found,

the most probable age for this sample is the Callovian.
This inference agrees with the fact that a layer of Callov-
ian jasper occurs at the Rătei section whereas the Oxford-
ian deposits are represented only by resedimented clasts in
the Kimmeridgian limestone.

Sfânta Ana (Bucegi Massif) –  By applying the UAZ95

zonation, the sample can be assigned to the UAZ 8 (mid-
dle Callovian—early Oxfordian) due to Gongylothorax  fa-
vosus Dumitrica (UAZ 8—10), Eucyrtidiellum  unumaense
s.l. (Yao) (UAZ 3—8; Fig. 7.29) and Podobursa  polyacan-
tha (Fischli) (UAZ 5—8; Fig. 7.18). By means of UAZ-SA,
the age spans the UAZ C (middle Oxfordian) for the pres-
ence of Emiluvia  orea Baumgartner (UAZ C—F) and
Eucyrtidiellum  unumaense s.l. (Yao) (UAZ A—C). The sam-
ple spans the middle Oxfordian.

irnea  (Piatra Craiului Mts) – By applying the UAZ95

zonation, the resulting age spans UAZ 8—10 (middle Call-
ovian—early Oxfordian to late Oxfordian—early Kimmerid-
gian) by the presence of Gongylothorax  favosus  Dumitrica
(UAZ 8—10), Zhamoidellum  ventricosum Dumitrica (UAZ
8—11),  Eucyrtidiellum nodosum Wakita (UAZ 3—10) and
Tritrabs  casmaliaensis (Pessagno) (UAZ 4—10). Through
the UAZ-SA, the sample is assigned to the UAZ C (middle
Oxfordian) by the presence of Zhamoidellum  ventricosum
Dumitrica (UAZ C—F) and Eucyrtidiellum unumaense s.l.
(Yao) (UAZ A—C; Fig. 8.21). The age assignment of  irnea
is middle Oxfordian.

Umeri (Piatra Craiului Mts) – By way of UAZ95 zona-

tion, the age is referred to the UAZ 8—9 (middle Callov-
ian—early Oxfordian to middle—late Oxfordian) for the
occurrence of Archaeodictyomitra  apiarium (Rüst) (UAZ
8—22; Fig. 8.10), Zhamoidellum  ventricosum Dumitrica
(UAZ 8—11; Fig. 8.23) and *Ristola procera (Pessagno)
(UAZ 5—9; Fig. 8.4). By applying the UAZ-SA zonation,
the age is stated as the UAZ D—E (?middle—?late Oxford-
ian to ?late Oxfordian—early Kimmeridgian pars) by the
presence of Archaeodictyomitra  apiarium (Rüst) (UAZ D—F),
Cinguloturris  carpatica Dumitrica (UAZ D—F; Fig. 8.12),
Eucyrtidiellum  nodosum Wakita (UAZ B—E; Fig. 8.20),
Tetratrabs  zealis (Ožvoldová) (UAZ B—E; Fig. 8.1), Tran-
shsuum  brevicostatum gr. (Ožvoldová) (UAZ A—E;
Fig. 8.5) and Williriedellum  carpathicum Dumitrica (UAZ
B—E; Fig. 8.24). The sample can be assigned to middle—
late Oxfordian.

Vladu ca  (Piatra Craiului Mts) – By means of UAZ95,

the age of the sample is assigned to the UAZ 8—10 (middle
Callovian—early Oxfordian to late Oxfordian—early Kim-

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OXFORDIAN AND CALLOVIAN RADIOLARIANS (SOUTHERN CARPATHIANS, ROMANIA)

Fig. 7. 

Continued from previous page.

    16  – *Pterotrabs arcuballista Dumitrica, Baumgartner et Goričan, Sf. Ana,  150;  17  – Podobursa

chandrika  (Kocher), Strunguli a,  150;  18  – Podobursa  polyacantha  (Fischli), Sf. Ana,  150;  19  – *Palinandromeda podbielensis
(Ožvoldová), Strunguli a,  100;  20  – Napora lospensis Pessagno, Sf. Ana,  150;  21  – Podobursa triacantha (Fischli) gr., Strunguli a,  150;
22  – *Saitoum sp., Sf. Ana,  200;  23  – Mirifusus dianae dianae (Karrer), Strunguli a,  100;  24  – Tethysetta  dhimenaensis  dhimenaensis
Baumgartner, Rătei,  200; 25 – *Transhsuum maxwelli (Pessagno) gr., Strunguli a,  150; 26 – *Hsuum speciosum Hull, Rătei,  150;
27  – *Sethocapsa sp. aff. S. exagona Hori, Rătei,  300; 28  – *Xitus sp., Sf. Ana,  200; 29 – Eucyrtidiellum unumaense (Yao) s.l., Sf.
Ana,  300;  30  –  *Arcanicapsa sp., Sf. Ana,  300;  31 – *Stichocapsa  naradaniensis Matsuoka, Rătei,  300;  32 – *Praewilliriedellum
sp. aff. P. spinosum Kozur, Rătei,  300;  33 – Williriedellum carpathicum Dumitrica, Rătei,  300;  34 – Williriedellum (?) marcucciae
Cortese, Rătei,  300.

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BECCARO and LAZĂR

Fig. 8.  Upper Jurassic radiolarians (1—25) and sponge spicules (26—37) from the Piatra Craiului Mts (Southern Carpathians, Romania).
The taxa illustrated come from the Vladu ca, Umeri and  irnea sections. The species carrying an asterisk have not been used for build-
ing the UAZ-SA zonation (Beccaro 2006). The scale bar A corresponds to 200  m for photos at  100 and to 100  m for photos at

200; the scale bar B corresponds to 400  m for images at  75, to 100  m for images at  150 and to 50  m for images at  300; the

scale bar C corresponds to 100  m for photos at  250.  1 – Tetratrabs zealis (Ožvoldová), Umeri,  75;  2 – Tritrabs  ewingi worzeli
(Pessagno), Umeri,  100;  3 – Tritrabs ewingi (Pessagno) s.l., Vladu ca,  75;  4 – *Ristola procera (Pessagno),  Umeri,  150;  5  –
Transhsuum brevicostatum (Ožvoldová) gr., Umeri,  200;  6 – Pantanellium riedeli Pessagno, Umeri,  200; 7 – *Archaeodictyomitra
inornata Hull,  irnea,  250; 8 – *Archaeodictyomitra wangi Yang,  irnea,  250; 9 – *Archaeodictyomitra shengi Yang, Umeri,  200;

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OXFORDIAN AND CALLOVIAN RADIOLARIANS (SOUTHERN CARPATHIANS, ROMANIA)

meridgian) for the presence of Gongylothorax  favosus
Dumitrica (UAZ 8—10; Fig. 8.18), Bernoullius dicera
(Baumgartner) (UAZ 3—10) and Tritrabs  casmaliaensis
(Pessagno) (UAZ 4—10). Through  the UAZ-SA the age
spans the UAZ D—E (?middle—?late Oxfordian to ?late Ox-
fordian—early Kimmeridgian pars) thanks to the presence
of  Cinguloturris  carpatica Dumitrica (UAZ D—F), Tet-
ratrabs  zealis (Ožvoldová) (UAZ B—E) and Transhsuum
brevicostatum gr. (Ožvoldová) (UAZ A—E). The radiolari-
an assemblages of Vladu ca is more probably referred to
middle—late Oxfordian, in accordance with the other sam-
ples of the Piatra Craiului area.

In summary, the samples from the Bucegi Massif and Pi-

atra Craiului Mts are assigned to biozones that include the
UAZ 8—10 (middle Callovian—early Oxfordian) and the
UAZ C—E (middle Oxfordian to ?late Oxfordian—early Kim-
meridgian  pars). The most probable age for these samples is
the middle Oxfordian. The only exception is represented by
the Rătei sample that is assigned to the Callovian.

Overview on Jurassic siliceous sediments in the

Carpathian chain

The geological setting of the Southern Carpathians (Ro-

mania) is very similar to other regions of the Carpathian
chain and to the Northern Calcareous Alps. Jurassic sili-
ceous sediments occur in the Silica Nappe and Pieniny
Klippen Belt (Slovakia), in the Tatra Mts (Poland) and in
the Eastern Carpathians (Romania). The radiolarian con-
tent of these sediments were studied by Ožvoldová (1979,
1988, 

1998), Widz (1991), Dumitrica (1995a,b),

Ožvoldová & Frantová (1997), Ožvoldová et al. (2000),
Suzuki & Gawlick (2003).

In the Pieniny Klippen Belt (Slovakia) the radiolarites

are generally bracketed by red nodular limestones and the
age spans Bathonian—early Kimmeridgian depending on
the sections (Ožvoldová 1979, 1988; Ožvoldová & Fran-
tová 1997; Ožvoldová et al. 2000). In the Silica Nappe
(Slovakia) the radiolarites occur as lithoclasts within car-
bonate breccias and their age is late Bathonian—upper
Callovian (Sýkora & Ožvoldová 1996; Ožvoldová 1998).
In the Tatra Mts (Poland) the radiolarites are underlain by
nodular limestones and overlain by either nodular lime-
stones or marly shales or limestones; their age ranges from
Bajocian to Oxfordian (Widz 1991). In the northern part of

the Eastern Carpathians (Bucovina Nappe, Romania) the
radiolarites are underlain by dolomite and overlain by
shales; the age is late Callovian to Oxfordian (Dumitrica
1995a). In the western end of the Southern Carpathians
(Svinita area, Danube Valley, Romania) radiolarites occur
in the upper Oxfordian—lowermost Kimmeridgian cherty
limestones (Dumitrica 1995b). The siliceous facies of the
Northern Calcareous Alps (Austria) is hightly calcareous
and bracketed by red calcareous beds; the age spans Toar-
cian—early Tithonian (Suzuki & Gawlick 2003).

Suzuki & Gawlick (2003) defined their own zonation

for the Northern Calcareous Alps (Austria) while the
UAZ95 zonation of Baumgartner et al. (1995a) was suc-
cessfully applied to some radiolarian assemblages from
the Carpathian chain. The radiolarites of the Silica Nappe
(Slovakia) represent the youngest preserved member of the
Jurassic sequence in the Slovak Karst and contain the old-
est Jurassic radiolarian assemblages from the Slovak West-
ern Carpathians: such assemblages are referred to the UAZ
5—7 (latest Bajocian—early Bathonian to late Bathonian—
early Callovian) (Ožvoldová 1998). In the Pieniny Klip-
pen Belt (Slovakia), the green-grey radiolarites of the
Kysuca Succession are assigned to the UAZ 8—10 (middle
Callovian—early Oxfordian to late Oxfordian—early Kim-
meridgian), and the radiolarian limestones of the Czertezic
Succession began only in the Oxfordian (UAZ 9—10: mid-
dle—late Oxfordian to late Oxfordian—early Kimmeridgian)
(Ožvoldová et al. 2000).

The new radiolarian data from the Bucegi and Piatra

Craiului Mts (Southern Carpathians; this paper) refer all
siliceous sediments to Oxfordian, and are in agreement
with the analogous facies of other Carpathian areas. The
Rătei sample (Bucegi Massif) is the only one assigned to
late Bathonian-middle Oxfordian (more likely Callovian),
and this age also agrees with other Carpathian siliceous
deposits.

Comparison between the Jurassic siliceous

sediments in the Southern Carpathians (Romania)

and other Tethyan sections

The radiolarian assemblages of the Bucegi Massif and

Piatra Craiului Mts (Southern Carpathians, Romania) are
equivalent to coeval assemblages from other Tethyan sec-
tions. The siliceous sediments are widespread in the basins

Fig. 8. Continued from previous page.

    10 – Archaeodictyomitra apiarium (Rüst),  Umeri,  250;  11 – *Archaeodictyomitra  rigida Pessagno,

Umeri,  250; 12 – Cinguloturris carpatica Dumitrica, Umeri,  200; 13 – Loopus sp. aff. L. primitivus (Matsuoka et Yao), Umeri,  250;
14 – Loopus doliolum martae Beccaro, Umeri,  300; 15 – *Loopus sp. aff. L. doliolum martae Beccaro, Umeri,  300; 16 – Tethysetta dhi-
menaensis ssp. A sensu Baumgartner et al. (1995b), Umeri,  250; 17 – *Protunuma sp.,  irnea,  300; 18 – Gongylothorax favosus Dumitrica,
Vladu ca,  300;  19 – *Sethocapsa  funatoensis Aita, Umeri,  200;  20 – Eucyrtidiellum nodosum Wakita, Umeri,  300;  21 – Eucyrtidiellum
unumaense (Yao) s.l.,  irnea,  300; 22 – *Praezhamoidellum sp. cf. P. yaoi Kozur,  irnea,  250; 23 – Zhamoidellum ventricosum Dumitrica,
Umeri,  200; 24 – Williriedellum  carpathicum  Dumitrica, Umeri,  250;  25 – *Amphipyndax sp., Umeri,  300;  26 – Amphiox (Diactine),
Strunguli a,  50; 27 – Strongyle (Diactine), LaP 1,  100; 28 – Amphiox (Diactine), LaP 1,  100; 29 – Tylostyle (Monoactine), LaP 1,  100;
30 – Dichotriaene (Tetractine), LaP 1,  100; 31 – Amphidiscae (Diactine), LaP 1,  250; 32 – Oxycalthrop (Tetractine), LaP 2,  100;
33 – Oxysphaeraster (Polyactine), LaP 1,  200;  34 – Oxyaster (Polyactine), LaP 2,  100;  35  – Phyllotriaene (Tetractine),
Strunguli a,  75; 36 – Anatriaene (Tetractine), Strunga,  100; 37 – Cricorhabds (Diactine), Strunga,  100; 38 – Pinakid (Tetractine),
Sf. Ana,  200; 39 – Oxycalthrop (Tetractine), Rătei,  100; 40 – Criccalthrop (Tetractine), Rătei,  100; 41 – Rhax, Vladu ca,  100.

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318

BECCARO and LAZĂR

of the Hellenides, Dinarides, Julian Alps, Southern Alps
and Sicily. In the Pindos-Olonos Zone (Hellenides,
Greece) the siliceous sediments are represented by shales,
marls and radiolarites; the age ranges from Early Jurassic
to Turonian (De Wever & Cordey 1995). In the Budva
Zone (Dinarides, Montenegro), the siliceous sediments are
represented by cherty limestones and shales alternated
with resedimented carbonates; the age spans the Triassic/
Jurassic boundary until the Turonian (Goričan 1994,
1995). In the Mangart area (Julian Alps, Slovenia), the ba-
sins were filled by biogenic material coming from the ad-
jacent carbonate platform, and the siliceous sediments are
Toarcian—early Kimmeridgian in age (Šmuc & Goričan
2005). In the Lombardian Basin (Southern Alps, Italy), the
radiolarites are alternated with shales and marls, and the
first radiolarians are Bajocian in age (Baumgartner et al.
1995c). In the Belluno Trough (Southern Alps, Italy), the
siliceous deposits are constituted by chert and limestones
intercalated with platform-derived material, and range Toar-
cian—Kimmeridgian (Baumgartner et al. 1995c). In the Sica-
nian Basin (Sicily, Italy), the siliceous sediments are the
most widespread during the Middle Jurassic, followed by
deep water limestones and marls (De Wever 1995).

The siliceous sediments abundantly occur also on the

submarine plateaux of the Southern Alps and Sicily (Italy)
where the Rosso Ammonitico Medio (RAM) represents the
intermediate pelagic siliceous member of the Rosso Ammo-
nitico Formation. On the Trento Plateau (Southern Alps),
the first siliceous deposition started in the Toarcian and
reached its maximum with the deposition of RAM during
the Callovian—Oxfordian; some platform-derived oolitic
grainstones are intercalated in the successions at different
levels (Baumgartner et al. 1995c). In the Trapanese Domain
(Sicily), the siliceous sediments of RAM appear in the mid-
dle Oxfordian and last till Kimmeridgian; they are alternat-
ed with limestones and marls (Beccaro 2006).

Even though the lower and the upper limits of the sili-

ceous facies in all the cited localities are diachronous, the
siliceous sediments are the most widespread everywhere
(in basins as well as on topographic highs) during the Ox-
fordian. In the Southern Carpathians (Getic Domain) the
siliceous facies is almost only restricted to the Oxfordian
(this paper). The radiolarian assemblage of Rătei (Bucegi
Massif, Southern Carpathians) is the only one referred to
late Bathonian—middle Oxfordian (more likely Callov-
ian): this sample is coeval with the basinal siliceous suc-
cessions of the Southern Alps, Julian Alps, Dinarides and
Hellenides.

As we can infer from the above discussion, the siliceous

sediments are mostly intercalated with resedimented car-
bonates only: this marks a strong difference in comparison
with the Romanian successions in which the siliciclastic
component is abundant. In spite of this clastic abundance,
the Oxfordian levels are truly siliceous and rich in radi-
olarians. Furthermore, no evidence of interrupted sedimen-
tation has been found in the Romanian sections, and the
radiolarians are mostly restricted to the middle Oxfordian,
which probably records the maximum of the siliceous sed-
imentation in the Tethys.

The siliceous sediments are easy recognizable in all in-

vestigated sections in Italy (Beccaro et al. 2002; Beccaro
2006) and in Romania (this paper) but a clear feature char-
acterizes the Romanian successions: almost all the sili-
ceous facies at the Bucegi Massif and Piatra Craiului Mts
are not more than 1 m thick. Conversely, in the Southern
Alps, the thickness ranges from 9 m at Ceniga to 100 m at
Coston delle Vette (Trento Plateau), and it is around 40 m
in the Lombardian Basin; in Sicily the average thickness
is approximately 20 m. It seems that the paleoenviromen-
tal conditions favoured the siliceous deposition in Italy
(as proved by thick deposits) and that only the siliceous
maximum was recorded in the Southern Carpathians area.

A common element between the Italian and the Roma-

nian siliceous sediments is that they often occur at the top
of condensed sequences sometimes displaying mineral-
ized hardgrounds: Strunga and Strunguli a (Southern Car-
pathians), Ceniga and Coston delle Vette (Southern Alps),
Fornazzo Strada and Fornazzo Cava (north-western Sici-
ly). The Strunga—Strunguli a (Bucegi Massif) and Piatra
Craiului sections are the most similar to the Italian ones.
At Strunga—Strunguli a the jaspers are comprised be-
tween limestones containing ammonites, and at Piatra
Craiului the siliceous sediments occur between red bio-
clastic limestone very similar to the Rosso Ammonitico
Formation.

The radiolarian assemblages of the Romanian and Ital-

ian samples (this paper and Beccaro 2006, respectively)
are altogether analogous from the taxonomical viewpoint
and also the sponge spicule content from the submarine
plateaux is similar in the studied samples.

Conclusions

The most representative Jurassic outcrops of the Bucegi

Massif and Piatra Craiului Mts (Southern Carpathians, Ro-
mania) have been studied for radiolarians.

Evaluation of the Preservation Index (PI), the Nassellar-

ia/Spumellaria ratio (N/S), and the sponge spicules/radi-
olarians ratio shows that the siliceous sediments of Piatra
Craiului ( irnea, Umeri, Vladu ca) and La Poli ie (Bucegi
Massif) were deposited in distal or relatively deep waters,
and that the cherty limestones of the Sfânta Ana Olistolith
were deposited in shallower waters or slope environment.
Concerning the other radiolarian assemblages (Strunga,
Strunguli a, Rătei) of the Bucegi Massif, the poor preser-
vation and the scarce radiolarian content did not allow a
good interpretation of the estimated indices.

The radiolarian assemblages are equivalent to coeval as-

semblages of other Tethyan sections and this allowed the
application of two radiolarian biozonations (UAZ95 of
Baumgartner et al. 1995a and UAZ-SA of Beccaro 2006)
in order to date directly the siliceous sediments for the
first time. The studied successions are mostly assigned to
the Oxfordian: UAZ 8—10 (middle Callovian—early Oxfor-
dian) of Baumgartner et al. (1995a) and UAZ C—E (middle
Oxfordian to ?late Oxfordian—early Kimmeridgian pars)
of Beccaro (2006). The only exception is represented by

background image

319

OXFORDIAN AND CALLOVIAN RADIOLARIANS (SOUTHERN CARPATHIANS, ROMANIA)

the radiolarian assemblage of the Rătei Valley that is very
probably assigned to the Callovian.

Comparison of the siliceous interval in the Southern

Carpathians with the analogous ones of other Tethyan sec-
tions suggests that even in environments with abundant
siliciclastic supply, the sedimentation drastically changed
during the Oxfordian and became siliceous.

The radiolarian data from the Bucegi Massif and Piatra

Craiului Mts (Southern Carpathians, Romania) has provid-
ed new information about the radiolarian assemblages in
Romania, enriched the knowledge about the Oxfordian
siliceous deposition in the Mediterranean area and in-
creased the database of the INTERRAD Jurassic-Creta-
ceous Working Group (Baumgartner et al. 1995c). All this
has contributed to creat new and better-defined radiolarian
biozones for the Jurassic Mediterranean Tethys.

Acknowledgments:  This research has been carried out dur-
ing a post-doc fellowship provided to Paola Beccaro by
the Ministry for Foreign Affairs (Italy) within the Program
of Cultural Exchanges of the Ministry for Education and
Research (Romania). Paola Beccaro is grateful to Dr. Cris-
tina Panaiotu (Faculty of Geology and Geophysics, Uni-
versity of Bucharest, Romania) for her support during the
stay in Bucharest.  The scanning electron micrographs
have been taken at the Ivan Rakovec Institute of Paleon-
tology ZRC SAZU (Ljubljana, Slovenia) and at the Earth
Sciences Department of the University of Turin (Italy).
Travel and field work in Romania was funded to Dr. Lazăr
by the National University Research Council of Romania
(CNCSIS Romania) Grant 304 (2003—2005).

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