GEOLOGICA CARPATHICA
, APRIL 2018, 69, 2, 169–186
doi: 10.1515/geoca-2018-0010
www.geologicacarpathica.com
New results of microfaunal and geochemical investigations
in the Permian–Triassic boundary interval from
the Jadar Block (NW Serbia)
MILAN N. SUDAR
1,
*
, TEA KOLAR-JURKOVŠEK
2
, GALINA P. NESTELL
3
, DIVNA JOVANOVIĆ
4
,
BOGDAN JURKOVŠEK
2
, JEREMY WILLIAMS
5
, MICHAEL BROOKFIELD
6
and ALAN STEBBINS
6
1
Serbian Academy of Sciences and Arts, Knez Mihaila 35, 11000 Belgrade, Serbia;
*
milan.sudar1946@gmail.com
2
Geological Survey of Slovenia, Dimičeva 14, 1000 Ljubljana, Slovenia
3
Department of Earth and Environmental Sciences, University of Texas at Arlington, Arlington, TX 76019, USA; Faculty of Geology,
St. Petersburg State University, St. Petersburg, Russia
4
Geological Survey of Serbia, Rovinjska 12, 11000 Belgrade, Serbia
5
Department of Geology, Kent State University, Kent, OH 44242, USA
6
School for the Environment, University of Massachusetts at Boston, 100 Morrissey Blvd. Boston, MA 02125, USA
(Manuscript received September 28, 2017; accepted in revised form February 12, 2018)
Abstract: Detail results of microfaunal, sedimentological and geochemical investigations are documented from a newly
discovered section of the Permian–Triassic boundary (PTB) interval in the area of the town of Valjevo (northwestern
Serbia). The presence of various and abundant microfossils (conodonts, foraminifers, and ostracodes) found in the Upper
Permian “Bituminous limestone” Formation enabled a determination of the Changhsingian Hindeodus praeparvus
conodont Zone. This paper is the first report of latest Permian strata from the region, as well as from all of Serbia, where
the PTB interval sediments have been part of a complex/integrated study by means of biostratigraphy and geochemistry.
Keywords: Conodonts, Hindeodus praeparvus Zone, foraminifers, C–N–S isotopes, northwestern Palaeotethys.
Introduction
Permian and Triassic deposits are widespread in the Jadar
Block in NW Serbia and their specific palaeontological and
lithological/sedimentological characteristics are unique in
Serbia. Therefore, they have been the subject of intensive
geological studies. Generally, Upper Permian shallow-water
marine carbonate rocks contain diverse and very rich macro-
and micro-biocenoses (without ammonoids, but with brachio-
pods, bivalves, gastropods, algae, and foraminifers), whereas
in the Lower Triassic sediments fossil associations are rather
poor and are represented by rare molluscs, foraminifers and
ostracodes.
During numerous field investigations for this study in the
Jadar Block (NW Serbia), the Serbian and Slovenian authors
of this paper intended to document new geological data to
refine existing stratigraphical, lithostratigraphical and sedi-
mentological determinations. Then, special attention was
ini tiated for the purpose of establishing reference sections of
the PTB interval in this area of Serbia. These investigations
started in 2005, and until now their results have been pub-
lished in Sudar et al. (2007), Nestell et al. (2009), Crasquin et
al. (2010), and Sudar et al. (2014).
The aim of this paper is to confirm the presence of microfos-
sils and to present the results of a biostratigraphical, sedimen-
tological and geochemical study of the continuous carbonate
sedimentary succession from the Upper Permian to the Lower
Triassic in the Sitarička Glavica section in the vicinity of
Valjevo (Jadar Block, NW Serbia) (Fig. 1).
Geological setting
During the Permian–Triassic, the investigated Serbian
PTB Sitarička Glavica section was situated palaeogeogra-
phicaly in the northwestern Palaeotethys along the passive
margin of Pangea (Schobben et al. 2014) (Fig. 1A). At the
present time, the Jadar Block is located at the southern
margin of the Pannonian Basin and belongs to the central
part of the Balkan Peninsula. It occupies a large part of
north western Serbia, southern Srem (Vojvodina) and partly
extends westward over the Drina River into eastern Bosnia
(Fig. 1B).
The Jadar Block unit is today an exotic block emplaced into
the Vardar Zone before the Late Cretaceous. It is surrounded
by the Vardar Zone Western Belt, except on the farthest south-
eastern part where it is in direct contact with the Kopaonik
Block and the Ridge Unit (Fig. 1B). The Jadar Block differs
from the Vardar Zone Western Belt in lacking post-Liassic
sediments as well as in the absence of ultramafites, ophiolitic
melange, and Cretaceous flysch development (Filipović et
al. 2003).
In the investigated area, deposition occurred during the
Variscan and Early Alpine evolution with a domination of
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Dinaridic features. The later tectonic stage is characterized
by the sedimentation of the Upper Permian and lowermost
Triassic shallow-water marine carbonate, Anisian dolomite,
Ladinian “porphyrite” and pyroclastic rocks, Middle and Upper
Triassic platform-reefal limestone and a gradual tran sition into
Lower Jurassic limestone.
In the Jadar Block, the Upper Permian is represented by
the “Bituminous limestone” Formation, and the lower part of
Fig. 1. Locations of the Jadar Block (NW Serbia) and Sitarička Glavica section: A — Palaeogeography during the PTB interval with
the location of the next sections: JB — Jadar Block in NW Serbia; Ir — NW Iran and SC — South China (adapted and modified from Schobben
et al. 2014). B — Terranes of a part of the Balkan Peninsula (Karamata et al. 2000; Karamata 2006): SMU — Serbian-Macedonian Unit;
MVZ — Main Vardar Zone; KBRU — Kopaonik Block and the Ridge Unit; VZWB — Vardar Zone Western Belt; JB — Jadar Block;
DIE — Drina–Ivanjica Element; DOB — Dinaridic Ophiolite Belt and EBDU — East Bosnian-Durmitor Unit (modified after Sudar et al. 2014).
C ‒ Geographic position of the Sitarička Glavica section in the south-western part of Jadar Block (NW Serbia): SRB — Serbia; H — Hungary;
RO — Romania; BG — Bulgaria; FYRM — Former Yugoslav Republic of Macedonia; AL — Albania; CG — Crna Gora (Montenegro);
BiH — Bosnia and Herzegovina; HR — Hrvatska (Croatia).
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the Lower Triassic belongs to the Svileuva Formation
(Filipović et al. 2003). They are both time equivalent with
formations of the Southern Carnic Alps, the first one with the
Bellerophon Formation, and the second one with the lower
part of the Werfen Formation.
Materials and methods
For the purpose of this study, a total of 26 samples were
processed for conodonts and making of thin sections. During
the field work in 2012, 19 composite samples for conodonts
were collected and only one of them (KM4) was productive.
Therefore, this level was resampled in detail in 2013 when
seven additional samples were collected and all of them turned
out to contain conodonts. The stratigraphic position of the
samples is presented in Figs. 2, 3.
The laboratory preparation of the samples were carried out
at Geological Survey of Slovenia (GeoZS), Ljubljana where
all micropalaeontological and sedimentological materials
are stored and inventoried under the repository numbers
5088‒5102 and 5328‒5334 and abbreviated GeoZS. The stan-
dard technique to process conodont samples with the use of
dilute acetic acid was applied and followed by heavy liquid
separation. The illustrated conodont elements presented herein
were photographed using the JEOL JSM 6490LV Scanning
Electron Microscope at the Geological Survey of Slovenia.
The microphotographs of foraminifers were taken in the
Depar tment of Earth and Environmental Sciences, University
of Texas at Arlington, Arlington, USA. Scanning electron
microscope images of framboidal pyrite were obtained from
the University of Massachusetts Boston Environmental
Analytical Facilitites, USA.
The Sitarička Glavica section
The Sitarička Glavica section contains a newly discovered
PTB interval exposed along the road Valjevo-Poćuta (Bajina
Bašta) near the dam Stubo-Rovni, about 100 km SW from
Belgrade and 14 km WSW of the town of Valjevo
(N 44º14’33.8”, E 19º43’20.3”) (Fig. 1C). The section is loca-
ted near the village of Sitarice just before the bridge over
the Tara River, a small tributary of the Jablanica River.
At the beginning of our investigations this section was named
Krivi Most (abbreviation for samples = KM).
Detail field investigations of the joint Serbian–Slovenian
research team of geologists (M. Sudar, D. Jovanović, T. Kolar-
Jurkovšek, and B. Jurkovšek) were done in 2012, 2013 and
2016. The entire studied section is over 50 meters thick and
consists of mostly tectonized Upper Permian and Lower
Triassic sediments of which only a 17.74 m thick interval not
disrupted by a shear zone was sampled for microfaunal and
sedimentological investigations (Figs. 2, 3).
Fig. 2. a — Sitarička Glavica section; b — panoramic view of Sitarička Glavica section; c‒ e — positions of samples KM7 (c), KM11 (d)
and KM18 (e).
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Lithology and sedimentology
The Sitarička Glavica section is subdivided into two parts,
i.e. into four units according to field investigations based on
macroscopic (lithologic) characteristics, and later by detailed
sedimentological and micropalaeontological studies.
The lower part, Unit 1, 7.22 m thick, is represented by black
and dark grey thick- to thin-bedded bituminous, predomi-
nantly nodular limestone (wackestone, very rare mudstone)
intercalated rarely with very thin layers of calcisiltite and limy
shale. The rocks of the following units, 2 (2.22 m), 3 (7.37 m)
and 4 (0.95 m), are different in lithology from the lower unit,
and are much lighter in colour with the prevalence of light
grey, yellow and almost brown shades. Also, sandy and mica-
ceous components in the upper part are typical (Fig. 2).
Unit 1 (samples KM1‒KM7) contains an abundant partly
fragmented macrofauna (brachiopods, gastropods, bivalves,
different parts of echinodermates, etc.) and microfossils (algae,
foraminifers, conodonts, ostracodes). Unit 2 (samples KM8‒
KM11) contains similar macro- and microfossils as are found
in Unit 1, but are not as abundant. The fossils are much more
fragmented, and in comparison with Unit 1 that had rich
foraminiferal assemblages, only a few species survived in
Unit 2. The second part of the section beginning with Unit 3
(samples KM12‒KM17) and then Unit 4 (samples KM18,
KM19) differs from the previous two units in very poor fossil
content yielding no foraminifers, but only fragments of
molluscs (bivalves, gastropods) and rare accumulations of
bivalves.
The lowermost part of the section (1.0 m; sample KM1) is
represented by silty wackestone. Its main characteristic is
the abundance of biodetritus comprising fragments of algae,
echinoids, and gastropods. The lower part of the following
2.27 m (samples KM2, KM3) is represented by wackestone,
party recrystallized, with abundant small foraminifers of
various species. Calcite veinlets, silty quartz and sericite, fine
organic matter are typical as well as fragments of algae and
other fauna. Very similar biodetritus is also present upward in
the mudstone, but foraminifers are less frequent and not
diverse. The next 2.40 m (samples KM4, KM5) are dark grey,
weakly laminated bioclastic wackestone. Due to the presence
of the Late Permian conodonts, the bed, first marked only as
KM4, was later studied in detail (samples KM4A‒KM4G).
Together with the conodonts, numerous parallel oriented
fragments of macro- and microfossils (gastropods, brachiopods,
crinoids, echinoids, and algae) and diverse foraminiferal species
are present. Very interesting and important is also the appea-
rance of four taxa of fusulinaceans which are not often found
in Upper Permian sediments in the Jadar Block area. Upward
(sample KM5) follows a bioclastic wackestone that contains
predominantly bivalves with thin and thick shells, and rare
foraminifers. This Unit passes into dark grey to black coloured
thin-bedded, laminated nodular bioclastic wackestone (sample
KM6), partly intercalated with grey calcisiltite and limy shale.
The final part of Unit 1 is topped by a 60 cm thick bed of dark
grey calcisiltite and limy shale. One layer of nodular clayey
limestone (sample KM7) with similar biodetritus as in the pre-
vious strata is present in this bed.
Unit 2, 2.20 m thick (samples KM8 to KM11), which con-
ditionally could represents the “transitional beds“ toward
the Lower Triassic sediments, is still in the Upper Permian
part of the section. Unit 2 is similar in lithology with the pre-
vious Unit 1 and is represented by thin-bedded silty–clayey
bioclastic wackestone intercalated with mm-cm thick calci-
siltite and limy shale. Siliciclastic detritus is mostly parallel
and weakly wavy oriented. Moreover, also an unequally/
irregularly fragmented macro- and microfauna both exhibit
stratification. Small foraminifers are scarce, however, they are
of Late Permian (Changhsingian) age (Fig. 3). Some of them
are replaced by silica or marked with fine organic matter.
Algae are very abundant and deformed. In the uppermost part
of this Unit abundant and different shell fragments are larger
than in the previous layers. Rare microfissures are filled with
organic matter.
The prevalence of bioclastic silty–clayey wackestone in
the lower part of the section (units 1 and 2), and the presence
of abundant small foraminifers, especially hemigordiopsids,
are usual for deposition under low energy conditions in a partly
restricted, very shallow water environment. Abundant bio-
detritus (gastropods, brachiopods, crinoid ossicles, parts of
echinoids, and algae) indicate back-reefal (lagoonal) origin.
Siliciclastic imput such as silty quartz, sericite, and fine
organic matter also suggests a very shallow environment.
These constituents are typical for Upper Permian
Changhsingian strata known from different regions of the
Palaeotethys (Korte & Kozur 2010; Kolar-Jurkovšek et al.
2011a, b; Farabegoli & Perri 2012).
In the interval of the section named as the “transitional
beds” (Unit 2) marine conditions obviously were changed.
In a partly restricted, shallow water environment some local
tectonic movements (presence of fragmented macro- and
microfauna) and weak oscillatory currents (wavy structure)
occurred. Only some rare species of Late Permian forami-
nifers survived in the transitional interval. This diminishment
of species could be explained with the beginning of mass
extinction which continued gradually (Fig. 3).
The upper part of the sampled section is first represented by
Unit 3 (7.37 m) that consists of thin-bedded sandy, silty–
clayey limestone, and micaceous biomicrosparite frequently
interbedded with micaceous siltstone (shale) (samples from
KM12 to KM17). The limestone is mostly parallel laminated
and weakly graded. Occasionally it contains concentrations of
sparitic shell fragments of bivalves that exhibit stratification
(sample KM14). Sporadically there appears thin (less than
1 mm) parallel concentrations of siliciclastic detritus: fine
sandy/silty quartz grains and sericite with submm-thin ferru-
ginous rhomboidal calcite concentrations. Dolomite is rare
and numerous calcite veins cut the rock. Sample KM17
represents a coquina with very frequent small indeterminable
bivalve shells.
The last Unit 4 (0.95 m) starts with bedded sparitic lime-
stone ‒ ooidal grainstone (sample KM18). Ooids are simple
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MICROFAUNAL AND GEOCHEMICAL STUDIES IN THE P–Tr BOUNDARY INTERVAL, JADAR BLOCK, SERBIA
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Fig.
3.
Geologic
al
colum
n, conodont stratig
raphic
ranges
and
zone,
distribution
of the
species
of foraminifers
(A
) and
the
last
appearance
of their
genera
(B
) with
the
appearance
of the
genus
Micr
oconchus
in
th
e
Si
ta
rič
ka
Glavica
section,
Jadar
Block,
NW
Serbia.
Legend:
1
—
limestone; 2
—
silty-clayey limestone;
3
—
limestone types:
W
—
wackestone,
M
—
mudstone,
G
—
grains
to
ne
;
4
—
limy
siltstone;
5
—
calcisiltite
and
limy
shale
;
6
—
parallel
lamination;
7
—
ooids;
8
—
ferruginous
matter;
9
—
mica;
10
—
algae;
11
—
small
foraminifers;
12
—
fusulinaceans;
13 — brachiopods; 14 — gastropods; 15 — bivalves; 16 — echinoderms (crinoid ossicles, holothurian sclerites, and parts of echinoids); 17 — conodonts; 18 — ostracodes.
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with one, rare two or three, superficial cortex, filled with
sparite. They are usually flattened, marked with fine ferru-
ginous matter. Fragments of recrystallized shells are rare.
The final part of the section (sample KM19) is represented by
calcisiltite and limy shale with small amounts of silty quartz,
sericite and organic matter.
The sediments of the terminal part of the section were
deposited on a wider area in a shallow epeiric shelf of ramp
with very low slope angle. Due to occasional tidal currents and
higher water energy ooidal grainstone was formed. The grain-
stone is followed by concentrations of shell fragments which
alternate with siliciclastic (sandy, silty) concentrations.
Chronostratigraphy, biostratigraphy and the Permian–
Triassic boundary
Upper Permian and Lower Triassic sediments are recog-
nized in the Sitarička Glavica section. A Changhsingian, latest
Permian conodont Hindeodus praeparvus Zone has been iden-
tified within the lower part of the section (units 1 and 2) on
the basis of very diverse and abundant fossil associations,
especially biostratigraphic characteristics of conodonts and
foraminifers. The sediments of this part of the section belong
to the “Bituminous limestone” (Bellerophon) Formation.
Although the absence of the microfossils is evident in the last
part of the section (units 3 and 4), according to the geological
position, the lithological and sedimentological characteristics
suggest that these strata belong to the lower part of the
Svileuva (Werfen) Formation of the lower levels of the Lower
Triassic (Fig. 3).
The boundary between the Upper Permian and the Lower
Triassic in the investigated section is placed at the level of
9.42 m above the sample KM11. This boundary is a litho-
logical boundary with the evident change of lithological
characteristics of the exposed sediments. The sample KM11
could also represent the level of local (?mass) extinction of
foraminifers in the section, and for this reason could have
biostratigraphic meaning. It is also possible that the absence of
foraminifers above the sample KM11 could be also connected
with the change of lithofacies.
Conodonts and accompanied isolated microfauna
Conodont dating
A very poor conodont fauna was obtained from the Sitarička
Glavica section (samples KM4D, KM4F, KM4G). Preservation
of conodont elements is moderate and they are black in color
and have a Conodont Alteration Index (CAI) value of approxi-
mately 5 sensu Epstein et al. (1977). All extracted conodont
elements are assigned to the single genus Hindeodus of which
only the species Hindeodus praeparvus Kozur and H. lati
dentatus (Kozur, Mostler & Rahimi-Yazd) are confidently
determined. The state of conodont preservation enabled
the determination of P1 elements only, because the accom-
panied ramiform elements are very fragmented. A few of
the hindeodid specimens differ from other elements in having
a widely open and deeply excavated basal cavity in the central
part of the unit and thus show certain similarities with
H. eurypyge Nicoll, Metcalfe & Wang. Two specimens cur-
rently assigned to Hindeodus sp. (H. ex gr. H. eurypyge Nicoll,
Metcalfe and Wang) are illustrated in the Fig. 4: 7–8. H. prae
parvus and H. eurypyge first appear in the Changhsingian
(Permian) and range also into the lowermost Induan (Triassic).
H. praeparvus is a widespread zone marker of the last Permian
conodont Zone. Based on the absence of H. parvus, the col-
lected conodont assemblage is assigned to the H. praeparvus
Zone. This age is confirmed also by the presence of associated
typical Permian, Changhsingian smaller foraminifers and rare
fusulinids. The H. praeparvus Zone is present in the middle
part (samples KM4D‒KM4G) of the “Bituminous limestone”
(Bellerophon) Formation (Upper Permian, Changhsingian)
(Fig. 3).
The investigated isolated microfaunas yield also Late Permian
foraminifers present in 11 samples out of 19 (from KM1 to
KM11) (Fig. 3). Ostracodes are found in the samples KM2,
KM4D, KM4E, KM8 as well as some recrystalized crinoid
ossicles in the samples KM4B‒KM4E. Moreover, very rare
fish teeth are present in the samples KM4A and KM4C.
Comparison of conodont fauna with adjacent areas
The extracted conodont fauna of the Sitarička Glavica
section belongs to the HindeodusIsarcicella lineage and it is
assigned to the Changhsingian Hindeodus praeparvus Zone.
Its presence enables a comparison with coeval conodont
faunas of adjacent areas, as well as to faunas from some other
important sections of the Palaeotethys (Kozur 2003; Jiang
et al. 2007; Farabegoli & Perri 2012; Ogg 2012; Kolar-
Jurkovšek & Jurkovšek 2015).
The investigated conodont fauna of the study section is very
similar to the conodont fauna from the Komirić section located
also in the Jadar Block in NW Serbia. The fauna of both
sections are dominated by the species H. praeparvus and
accompanied by H. latidentatus, but with the absence of
Isarcicella (Sudar et al. 2007).
The species H. praeparvus has been so far reported from
all sections of the PTB interval that have been studied in
the Outer Dinarides as part of the Alpine–Mediterranean belt
on the Balkan Peninsula. It is a very common and characte-
ristic species that occurs in the uppermost strata of the
Bellerophon Formation (Late Permian, latest Changhsingian)
of western Slovenia (Kolar-Jurkovšek et al. 2011a, b; Kolar-
Jurkovšek & Jurkovšek 2015).
The Lukač section near Žiri in Slovenia represents a key
section to define the PTB interval strata in the Outer Dinarides
due to the presence of the conodont species H. parvus which is
used as a marker of the Permian–Triassic (PT) boundary at
the GSSP in Meishan, China (Chen et al. 2015), according
to an international criterion of the IUGS (Kolar-Jurkovšek &
Jurkovšek 2007). Therefore it is taken also as a standard
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section for the conodont zonation for the entire Dinarides area
(Kolar-Jurkovšek et al. 2011a, b; 2012; 2013). The association
composition of the latest Changhsingian H. praeparvus Zone
in the Lukač section includes H. latidentatus, H. praeparvus,
H. cf. H. pisai, and Hindeodus sp.
Species H. eurypyge has been so far documented to occur
also in the Outer Dinarides. Its discovery is reported from
the Masore section, Slovenia where it appears in association
together with the zone markers H. praeparvus and Isarcicella
cf. I. prisca (Kolar-Jurkovšek et al. 2018). Moreover, speci-
mens referred to H. cf. H. eurypyge were collected in the
Isarcicella lobata Zone of the Lukač section (Kolar-Jurkovšek
et al. 2011a, b).
Foraminifers
In the Sitarička Glavica section, the assemblage of forami-
nifers is represented by species typical for the Upper Permian,
Changhsingian (Figs. 5, 6). The assemblage is not diverse and
includes 21 species of 15 genera of small foraminifers and
four taxa of three genera of fusulinaceans.
Among small foraminifers the dominant forms are hemigor-
diopsids with a large number of individuals of some genera
such as Hemigordius and Neodiscus. Most tests of these genera
are recrystallized and replaced by silica. Besides hemigor dio p sids
rare nodosariids and globivalvulinids are also present.
The hemigordiopsids are represented by nine species such
as Hemigordius latispiralis Lin, Li & Sun, H. komiricensis
Nestell, Sudar, Jovanović & Kolar-Jurkovšek, H. hungaricus
Bérczi-Makk, Csontos & Pelikán, Multidiscus vlasicensis
Nestell, Sudar, Jovanović & Kolar-Jurkovšek, Midiella sp.,
Neodiscus sp., Agathammina cf. A. psebaensis Pronina-
Nestell, A. cf. A. ovata Wang, and A. sp. 1 (Fig. 3). The presence
of recrystallized hemigordiopsids indicates a very shallow
environment.
Nodosariids are represented by rare tests of species such as
Protonodosaria mirabilis caucasica (K. Miklukho-Maklay),
Fig. 4. Conodonts and crinoids from the Upper Permian, Changhsingian, H. praeparvus Zone; “Bituminous limestone” (Bellerophon)
Formation; Sitarička Glavica section, Jadar Block, NW Serbia. 1, 2, 4 — Hindeodus praeparvus Kozur. 1,2 — sample KM4F, 4 — sample
KM4G; 3 — Hindeodus latidentatus (Kozur, Mostler & Rahimi-Yazd). sample KM4F; 5, 6 — Hindeodus sp. sample KM4E; 7, 8 — Hindeodus
sp. (H. ex gr. H. eurypyge Nicoll, Metcalfe & Wang). 7 — sample KM4E, 8 — sample KM4D; 9 ‒14 — crinoid ossicles, sample KM4F.
a — upper, b — lateral view. Scale bar 100 µm (for Figs. 1‒8), and 200 µm (for Figs. 9‒14).
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Fig. 5. Foraminifers from the Upper Permian, Changhsingian; “Bituminous limestone” (Bellerophon) Formation; Sitarička Glavica section,
Jadar Block, NW Serbia. 1‒8 — “Eotuberitina reitlingerae” Miklukho-Maklay, axial sections. 1, 3 — sample KM2, thin section 71576;
2, 5, 8 — sample KM4, thin section 71614; 4 — sample KM2, thin section 71611; 6, 7 — sample KM4B, thin section 71876;
9‒11 — Hemigordius komiricensis Nestell, Sudar, Jovanović & Kolar-Jurkovšek. 9 — axial section of a completely recrystallized specimen,
10 — close to axial section, 11 — axial section of a partly recrystallized specimen. 9 — sample KM1, thin section 71562; 11 — sample KM4A,
thin section 71873; 12‒16 — Hemigordius latispiralis Lin, Li & Sun. 12, 13, 16 — axial sections, 14, 15 — axial sections of completely
recrystallized specimens. 12 — sample KM4, thin section 71614; 13 — sample KM4F, thin section 71877; 14 — sample KM11, thin section
71565; 15 — sample KM1, thin section 71562; 16 — sample KM4G, thin section 71832; 17‒21 — Hemigordius hungaricus Bérczi-Makk,
Csontos & Pelikán. 17, 18 — close to axial sections, 19, 20, 21 — axial sections of completely recrystallized specimens. 17 — sample KM4F,
thin section 71880; 18 — sample KM4, thin section 71568; 19, 20 — sample KM10, thin section 71560; 21 — sample KM11, thin section
71565; 22 — Midiella sp., axial section, sample KM4, thin section 71614; 23 — Agathammina cf. A. ovata Wang, close to axial section, sample
KM4A, thin section 71833; 24, 25 — Multidiscus vlasicensis Nestell, Sudar, Jovanović & Kolar-Jurkovšek. 24 — axial section, 25 — transverse
section; sample KM4E, thin section 71879; 26 — Neodiscus sp. 1, close to axial section, sample KM4B, thin section 71876; 27 — Neodiscus
sp. 2, close to axial section, sample KM4B, thin section 71836. Scale bar 100 µm.
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P. delicata (Wang), Pseudolangella conica (K. Miklukho-
Maklay), Cryptomorphina limonitica Sellier de Civrieux &
Dessauvagie, Frondina cf. F. paraconica (K. Miklukho-
Maklay), Geinitzina cf. G. orientalis K. Miklukho-Maklay,
G. cf. G. uralica simplex K. Miklukho-Maklay, Pachyphloia
cukurkoyi Sellier de Civrieux & Dessauvagie, Robuloides
acutus Reichel, and Astacolus permicus (K. Miklukho-
Maklay) (Fig. 3).
Globivalvulinids are represented by single species of the
genera Globivalvulina, Retroseptellina, Paraglobivalvulina,
and very rare tests of the genus Dagmarita (Fig. 3).
All of the listed species of small foraminifers occur in
the Changhsingian strata of different regions of the Palaeo-
tethys: in northwestern Serbia (Nestell et al. 2009), western
Slovenia (Nestell et al. 2011), in northern Hungary (Bérczi-
Makk et al. 1995), northern Italy (Groves et al. 2007), north-
western Caucasus (Miklukho-Maklay 1954; Pronina-Nestell
& Nestell 2001), Turkey (Sellier de Civrieux & Dessauvagie
1965; Groves et al. 2005), Transcaucasia (Pronina 1989), and
South China (Wang 1976; Zhao et al. 1981; Lin et al. 1990;
Zhang & Hong 2004; Song et al. 2006, 2007, 2009).
It should be noted that the attached tests of the unilocular
species identified as “Eotuberitina reitlingerae” Miklukho-
Maklay, are present in almost each sample (from KM1 to
KM11). These tests are characterized by varying shapes of
the test from bulbous with very narrow basal disk of the
attachment (Fig. 5: 2) to crescentiform with a transition from
a middle rounded to a wide flattened basal disk of the attach-
ment (Fig. 5: 1, 3–8). Specimens usually consist of one single
chamber, but sometimes two chambers can be seen (Fig. 5: 5,
8). In one-chambered tests the wall is microgranular, non-
perforate and thin (a characteristic feature for the genus
Eotuberitina Miklukho-Maklay), whereas in two-chambered
forms of the same shape of the chamber the wall is perforate
microgranular that, according to definition, is a characteristic
feature for the unilocular genus Tuberitina Galloway &
Harlton. The difference in the wall structure could depend on
the maturity of the tests: young specimens have a thin non-
perforate wall, whereas older tests have a thicker and perforate
wall. Also, the shape of the test could depend on substrates of
attachment. Nestell & Nestell (2006, p. 6) showed that in thin
sections of their new species Tuberitina variabilis from the
Middle Permian of West Texas, the shape of the chambers,
wall structure and its thickness can vary in one pseudocolony
“depending on the position of the section with respect to
the center of the test”. Based on these statements, the unilo-
cular forms from the Sitarička Glavica section are identified as
“Eotuberitina reitlingerae” because they have a crescentiform
chamber shape like E. reitlingerae, although this species is
described from the Middle Carboniferous of the Russian
Platform (Reitlinger 1950; Miklukho-Maklay 1958). Fora-
minifers similar to the illustrated herein tests of the species
“Eotuberitina reitlingerae” are recorded in almost all of the
Permian–Triassic transition interval sections studied in the
Palaeotethys area, but have been identified by various authors
as different genera and species. For example, in the Meishan
GSSP section, one-chambered tests with the same shape of the
chambers are identified as Tuberitina sp. and Diplosphaerina
inaequalis Derville by Song et al. (2007), or Eotuberitina
reitlingerae and Eotuberitina sphaera Lin by Song et al. (2006).
Two-chambered tests were identified by Song et al. (2006) as
Neotuberitina maljavkini (Mikhailov). In the Dajiang section
of the Nanpanjiang basin, both one- and two-chambered tests
are identified as the species Diplo sphaerina inaequalis (Song
et al. 2009). In northern Italy, in the Bulla section, one-
chambered crescentiform forms are identified as Diplo
sphaerina inaequalis (Groves et al. 2007); in north western
Serbia, in the Komirić section (Nestell et al. 2009) and in
western Slovenia, in the Lukač section (Nestell et al. 2011)
— as Tuberitina? sp. All of these unilocular forms from the
Permian–Triassic transition interval are probably the same,
and possibly represent a new species which could be described
after a careful revision of all unilocular forms of the family
Tuberitinidae with a precise definition of each genus and its
stratigraphic distribution.
Fusulinaceans are very rare and represented by only three
species such as Staffella cf. S. hupehensis Jing, Nankinella cf.
N. chongyangensis Jing, and Nankinella cf. N. acuta Lin in the
sample KM4D. Representatives of the genus Palaeofusulina
are extremely rare; only two tangential sections were seen which
did not allow identification on the specific level. The species
Staffella hupehensis and Nankinella chongyangensis have
been described from Changhsingian strata in southern part of
the Hubei Province (Jing 1992) and the species Nankinella
acuta from western Guizhou Province, China (Lin 1979).
The distribution of foraminiferal species in the Sitarička
Glavica section is given in Fig. 3. The only occurrence of
fusulinacean species are in sample KM4 (KM4A, KM4D).
Among abundant presence of small foraminifers in the lower
part of the Sitarička Glavica section, only four species of these
microfossils continue into sample KM11 (Fig. 3: A). No fora-
minifers were found in sample KM12 and above, in the upper
part of the section.
Usually, in Permian–Triassic boundary interval sections
described from many places of the world, the diverse latest
Permian assemblage of foraminifers is replaced by small tests
of opportunistic species of the genera Hyperammina (former
Earlandia) and Ammodiscus (former Cornuspira or Post cla
della) together with microconchids (Brönnimann et al. 1972;
Bérczi-Makk 1987; Groves et al. 2005, 2007; Song et al. 2009;
Nestell et al. 2011, 2015), an association that is not seen in
the Sitarička Glavica section.
We cannot say for sure that sample KM11 represents the
level of mass extinction of foraminifers in the section, and
their absence above this sample could possibly be connected
with changing lithofacies. However, the distribution and
extinction sequence of the genera of foraminifers (Fig. 3: B),
and their last appearance, in general, coincides with the distri-
bution and extinction of the genera observed at the Permian–
Triassic boundary interval in the Lung Cam section of northern
Vietnam (Nestell et al. 2015). In both sections, Sitarička
Glavica and Lung Cam, the mass extinction of foraminifers
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Fig. 6. Foraminifers from the Upper Permian, Changhsingian; “Bituminous limestone” (Bellerophon) Formation; Sitarička Glavica section,
Jadar Block, NW Serbia. 1 — Agathammina cf. A. psebaensis Pronina-Nestell, close to axial section, sample KM4, thin section 71614;
2 — Agathammina sp. 1, axial? section, sample KM2, thin section 71611; 3 — Protonodosaria mirabilis caucasica (K. Miklukho-Maklay),
close to axial section, sample KM4B, thin section 71876; 4 — Protonodosaria delicata (Wang), close to axial section, sample KM4G, thin
section 71832; 5 — Pseudolangella conica (K. Miklukho-Maklay), close to axial section, sample KM4, thin section 71614; 6, 7 — Frondina
cf. F. paraconica (K. Miklukho-Maklay). 6 — axial tangential section, sample KM2, thin section 71613; 7 — lateral section, sample KM4B,
thin section 71876; 8 — Frondina sp. 1, axial tangential section, sample KM9, thin section 71559; 9 — Cryptomorphina limonitica Sellier de
Civrieux & Dessauvagie, axial section, sample KM4F, thin section 71880; 10 — Geinitzina cf. G. orientalis K. Miklukho-Maklay, close to axial
section, sample KM2, thin section 71576; 11 — Pachyphloia cukurkoyi Sellier de Civrieux & Dessauvagie, axial lateral section, sample KM7,
thin section 71573; 12 — Globivalvulina lukachiensis Nestell, Kolar-Jurkovšek, Jurkovšek & Aljinović, tangential section, sample KM4B, thin
section, 71836; 13 — Geinitzina cf. G. uralica simplex K. Miklukho-Maklay, axial tangential section, sample KM2, thin section 71613;
14‒16 — Robuloides acutus Reichel, axial sections. 14 — sample KM4F, thin section 71877; 15 — sample KM2, thin section 71613; 16 — sample
KM4C, thin section 71878; 17 — ?Retroseptellina nitida (Lin, Li & Sun), tangential section, sample KM6, thin section 71561; 18 — Astacolus
permicus (K. Miklukho-Maklay), close to axial section, sample KM4B, thin section 71836; 19 — Dagmarita sp., axial tangential section, sample
KM4B, thin section 71836; 20 — Paraglobivalvulina cf. P. gracilis Zaninetti & Altiner, tangential section, sample KM4, thin section 71614;
21 — ?Palaeofusulina sp., tangential section, sample KM4A, thin section 71873; 22 ‒ Nankinella cf. N. chongyangensis Jing, close to axial section,
sample KM4, thin section 71568; 23‒26 — Nankinella cf. N. acuta Lin, axial sections. 23 — sample KM4, thin section 71568; 24, 25, 26 — sample
KM4, thin section 71614; 27 — Staffella cf. S. hupehensis Jing, axial section, sample KM4, thin section 71615. Scale bar 100 µm.
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happens step by step. The difference in the distribution of
genera of foraminifers between two sections is in the survival
of the genera Globivalvulina, Geinitzina and Nodosaria after
the mass extinction in the Lung Cam section, whereas in the
Sitarička Glavica section these genera are extinct in sample
KM11, which is, most probably, the level of mass extinction in
this section. The first appearance of the microconchid genus
Microconchus is in sample KM16. The genus appears in
the latest Permian and continues into the early Triassic
(Brönnimann & Zaninetti 1972; Nestell et al. 2015).
Geochemical investigations
Brookfield and Williams (in 2011), Brookfield (in 2013)
together with Sudar and Jovanović measured in detail the
Sitarička Glavica section and took samples for the geo-
chemical and sedimentological investigations, with prelimi-
nary results reported in Williams et al. (2013 a, b; 2014).
Although the detailed elemental and isotope geochemistry will
be given elsewhere, herein we summarize some of the main
results and suggest some causes.
Four negative δ
13
C
org
excursions are recorded in this PTB
section (Fig. 7A). Excursion #1 (−3 m to −0.5 m, ~ −7 ‰),
excursion #2 (−0.05 m to 2 m, ~ −1.6 ‰), excursion #3 (3 m
to 4 m, ~ −4.3 ‰), and excursion #4 (5 m to 8 m, ~ −2.5 ‰).
The four negative δ
13
C
org
excursions are associated with chan-
ges in lithofacies from gray to dark shale (excursion #1), and
changes in fauna (excursions 2–4). The 2
nd
and 3
rd
excursion
straddle the PTB, the 2
nd
excursion with the appearance of
crinoids, brachiopods, bryozoan, foraminifers, and molluscs,
whereas the 3
rd
excursion occurs with only molluscs.
Fig. 7. Parallel review of the results of geochemical (Willams et al. 2013 a, b; 2014: 7A) and stratigraphic/biostratigraphic investigations
(this paper: 7B) in the Sitarička Glavica section, Jadar Block, NW Serbia. The four negative δ
13
C
org
excursions recorded in the section are shown
on Fig. 7A.
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The 4
th
excursion, occurs with the stromatolite-like bed
(Fig. 7A and KM16 of Unit 3 in Fig. 7B). These negative shifts
are indicative of a decrease in primary productivity. The abrupt
decrease δ
13
C
org
suggest a crash in the biological pump (Kump
2005), creating a biological crisis. Excursion #1 and #2 are
similar to the δ
13
C
org
signature of the GSSP Meishan section,
which occurs before the PTB (Korte & Kozur 2010). Like
other PT sections in the Palaeotethys, Sitarička Glavica δ
13
C
org
signature suggests a major perturbation in the C-cycle during
the extinction interval and a long recovery.
The δ
15
N
org
signature suggests that the surface waters were
dominated by N-fixation, derived from diazotrophs that con-
verted atmospheric N into NH
4
(Fig. 7A; Quan & Falkowski
2009). The depleted signature may suggest low depositional
oxygen conditions. The negative excursion recorded near the
PTB is similar to Rizvanuša, Croatia (Fio et al. 2010), Guryul
Ravine, Kashmir, India (Algeo et al. 2007) and GSSP Meishan,
South China (Cao et al. 2009; Luo et al. 2011). This abrupt
negative shift maybe attributed to catastrophic conditions
where the ecological disaster resulted in enhancement of
N-fixation from widespread diazotrophs (Luo et al. 2011).
The δ
34
S
pyrite
signature suggests decoupling of the S-cycle
during the Late Permian due to the fluctuations from enriched
to depleted δ
34
S
pyrite
(Fig. 7A). Framboidal pyrite occurs in
the Bellerophon Formation, whereas oxidized pyrite is present
in the Werfen Formation. Framboids occur between − 9 m to
3 m (PTB) suggesting syngenetic formation (Fig. 8; Williams
2013b). The depleted δ
34
S
pyrite
signature along with the pre-
sence of framboidal pyrite strongly suggests widespread
oxygen depletion (Shen et al. 2007). Evidence of framboids
coupled with positive δ
34
S
pyrite
values (− 9 m, −4 m, and 3 m)
suggest a closed S-system where the SO
4
2-
reduction exceeds
the supply, with the ensuing Rayleigh fractionation causing
an enriched isotopic signal (Figs. 7A, 8; Williford et al. 2009).
Oxidizing framboids occur between 4 m to 10 m, indicating
late diagenetic formation. The occurrence of partially oxidized
framboids (5 m) is indicative of syngenetic and late diagenetic
formation (Figs. 7A, 8; Williams et al. 2013b). At the PTB,
evidence of both framboidal and euhedral pyrite suggest both
syngenetic and precipitation formation. Euhedral formation
through precipitation formation is probably due to the occur-
rence of an oolite factory at the PTB from the decrease in
skeletal CO
3
2-
(Haas et al. 2007; Li et al. 2015). The presence
of oolite and euhedral pyrite along with a coral gap, may serve
as evidence of widespread ocean acidification in the Palaeo-
tethys during the extinction interval (Li et al. 2015).
The elemental geochemical changes across the PTB in
the Sitarička Glavica section are minimal, which indicates little
physical environmental change, such as source type and con-
ditions. We plot element/Al ratios to identify anomalies due to
biology or geochemistry, which show up as deviations from
average element/Al values and values of reference sediments
(Calvert & Pedersen 1993). The ratios are shown on arithmetic
log plots to emphasize the order of magnitude differences as
the actual values are frequently so low as to make small diffe-
rences appear important on arithmetic plots. For the major
elements, Si/Al, Ti/Al, Fe/Al and Mn/Al ratios change little
through the section, showing that these elements correlate
with Al (Fig. 9). Mg/Al, Ca/Al and K/Al tend to drop above
the extinction horizon, whereas Na/Al tends to rise as the
litho logies change to less carbonate-dominated. For the minor
elements, the ratios to Al change little except for high values
of most ratios within 1 meter of the Bellerophon/Werfen con-
tact, in beds 8 to 11 during the δ
13
C
org
and δ
15
N
org
and δ
34
S
pyrite
positive excursions; above which Sc/Al, Ge/Al, Zr/Al, Nb/Al,
Hf/Al, Th/Al tend to increase, whereas Be/Al, B/Al, Ni/Al,
Fig. 8. Scanning electron microscope
images of samples from the Sitarička
Glavica section, Jadar Block, NW Serbia.
Framboidal pyrite is observed in the
Bellerophon Formation, euhedral pyrite is
observed at the PTB, and oxidized pyrite is
observed in the Werfen Formation.
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As/Al, Y/Al, Mo/Al, Sn/Al, Sb/Al, Cs/Al, Pb/Al, and U/Al
tend to drop, and TOC/Al drops by an order of magnitude
(Williams et al. 2014).
The source character can be inferred from various indices.
The Chemical Index of Alteration (CIA) summarizes chemical
alteration during weathering, transportation and deposition
and gives geochemical estimations of provenance (Nesbitt &
Young 1982). The Index of Compositional Variability (ICV)
includes Fe, Mg, and Mn, and does not require calculation of
non-carbonate Ca, and uses oxides rather than moles (Cox et
al. 1995). Average basalt and average granite have very diffe-
rent ICV values of 2.20 and 0.95 (Li 2000). So, mudstone with
the same degree of weathering (the same CIA) may have
different ICV values, indicating composition of the source
area; though calcareous sediments give misleading values in
all cases. The calcareous Serbian sediments (minimum CaO is
12.77 %) are all misleading as their ICV values are at or higher
than the basalt value. But, Serbian CIA values for samples
with less than 50 % of carbonate are 56 –72, and indicate
a moderate degree of chemical weathering of the parent mate-
rial with no marked changes up the section, and are compa-
rable to reference sandy and silty mudstone, and to Recent
North American and Asian rivers (Li & Yang 2010) (Fig. 10).
The Na/K, K/Fe, and K/Fe+Mg ratios can similarly be used
to infer source characteristics and weathering. Na/K ratios
reflect the maturity of clastic sediments. Na/K ratios above 1
indicate immature sediments, whereas those below 1 indicate
more mature sediments. The Serbian sediments have generally
more mature Na/K ratios below the extinction horizon in
the more calcareous beds and less mature (but still below 1)
above (Fig. 10).
K/Fe and K/(Fe+Mg) ratios reflect the contribution of acidic
versus basic rocks and the rate of chemical weathering of
K-felspar (Nesbitt et al. 1997). In areas of diverse rock sources
like the present Atlantic margins, relatively low K/Fe values of
tropical areas (0.26) contrast with higher K/Fe values (0.43)
for arid regions (Govin et al. 2012). Serbian K/Fe values are
all higher than the arid region values except for two at +2 m
and +3 m straddling the extinction level. This range of values
is not only compatible with the extreme aridity inferred for
Permian–Triassic (PTr) source areas in the PTr palaeotropics
(Brookfield 2008), but with the possible wetter pluvial interval
at the PT boundary in northern Gondwanaland (Kreuser 1995).
The values above 0.5 probably indicate volcanic input
(Sageman & Lyons 2005). The Serbian K/(Fe+Mg) ratios do not
change much up section, but have a low at the extinction
Fig. 9. Majors ratios to Al.
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horizon, and are close to clastic reference sediment values, but
much higher than the reference limestone (Fig. 10).
In the West African deserts and the adjacent eastern Atlantic,
high Ti/Zr values occur in dust aerosols and marine clays
supplied from dust aerosols (>38–40) where softer abraded
ilmenite dust is concentrated, whereas lower values occur
in river and coastal clay sediments which are derived in part
from remobilized eolian lags (<30) where abrasion-resistent
zircons are concentrated (Govin et al. 2012; Patey et al. 2015).
The reference low Ti/Zr Chinese loess and Sahara Chad
dust values are misleading because the samples come from
Quaternary dust adjacent to and derived from bedrock sources
only locally remobilized by wind — particles have not had
time to significantly abrade. Only two Serbian Ti/Zr values
(at −8 m and + 0.05 m) reach anywhere near eolian values,
and thus most of the Serbian clays come from fluvial sources
(Fig. 10).
Nb/Ta ratios decrease in clays from arid areas (Nb/Ta ~15)
to humid areas (Nb/Ta ~ 8.5), as Nb is preferentially leached.
Serbian Nb/Ta ratios vary little around the remarkably con-
stant reference sediment value of 10, and are only slightly less
than the average Upper Continental Crust values of 13 (Barth
et al. 2000), though there is a tendency to have slightly lower
values around the PT boundary which may reflect wetter
conditions (Fig. 10).
Climatic change in source regions, without source compo-
sition changes, can be determined by fluctuations in Ti/Al, Ti/K
and Ti/Sc ratios. Wei et al. (2003) showed that sharp changes
in these correlated with Quaternary glacial/interglacial cycles,
with higher ratios in warmer periods due to increased chemi-
cal weathering. In eastern Atlantic surface sediments off the
West African deserts, intermediate Ti/Al values in areas of
high dust deposition contrast with Ti/Al values in areas domi-
nated by the input of suspended material from the Senegal,
Niger and Congo rivers (Govin et al. 2012). Serbian Ti/Al ratios
show little change except for a slight drop in unit 2 (the last
2.20 meters of the “Bituminous limestone” (Bellerophon)
Formation) and slight increase above (Fig. 10).
Fig. 10. CIA, ICV, Na/K, K/(Fe+Mg), Ti/Zr, Nb/Ta ratios.
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Various redox proxies involving transition elements and
U are commonly used such as V/Cr, V/(V+Ni), Ni/Co, U/Mo
and U/Th and though they are unreliable individually together,
they give better results (Wignall & Myers 1988; Jones &
Manning 1994; Tribovillard et al. 2006; Zhou et al. 2012).
Serbian V/Cr are all in the oxic field: V (V+Ni) are in the oxic
field in Unit 1 and are in the dysoxic field around 0 m and
above + 4 m; Ni/Co are in the suboxic-anoxic field below
−1 m and are in the dysoxic and oxic fields above, with some
reversals to suboxic-anoxic; U/Mo are mostly in the suboxic-
anoxic fields; Th/U are mostly in the subxic-anoxic field until
+ 4 m above which they are predominantly oxic (Fig. 11). There
is thus no consistency in these redox proxies in the Serbian
sediments; though on Ni/Co, U/Mo, Th/U conditions were
dysoxic below + 4 m and oxic above + 4 m. Th/U ratios give
more dysoxic conditions than the Mo/Al ratios though they
follow the same trends. The lack of consistency in these redox
proxies is disappointing, but anoxia seems present in units
1 and 2 with oxic conditions in Unit 3 above (Fig. 11).
Conclusions
The detail palaeontological, sedimentological and geo-
chemical investigations of strata from the PTB interval in
Sitarička Glavica section (Jadar Block, Valjevo, NW Serbia)
exhibit various and important features which can be summa-
rized as follows:
• Abundant and diverse macro- and microassociations
recorded exclusively in the lower part of the section enabled
the determination of the Changhsingian Stage within the
Upper Permian “Bituminous limestone” (Bellerophon)
Formation. The investigated conodont fauna from the
middle part of the Permian part of the section belongs to
the HindeodusIsarcicella lineage and, according to their
biostratigraphic characteristics, it is assigned to the
Changhsingian Hindeodus praeparvus Zone. The assem-
blage of foraminifers is richer, represented by species typi-
cal for the Upper Permian, Changhsingian, in the lower part
of the section.
Fig. 11. V/Cr, V(V+Ni), Ni/Co, U/Mo, Th/U.
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• The second part of the section (units 3 and 4) is without
microfossils (only rare sections and fragments of molluscs),
with clearly a change of sedimentologic characteristics and
geological/superpositional position determinated as Lower
Triassic, i.e. the lower part of the Svileuva (Werfen)
Formation.
• The boundary between the Upper Permian and the Lower
Triassic is placed at the level of 9.42 m of the section above
the sample KM11. This boundary is a lithologic boundary
and has also biostratigraphic importance. It is marked by
a rapid change of sedimentological characteristics and with
the clear absence of microfossils in the upper part of the
exposed sediments. The sample KM11 could also represent
the level of local (?mass) extinction of foraminifers in the
section, as confirmed by the changing of lithofacies.
• Although in all of the PTB investigated sections in NW
Serbia we have not yet found conodonts and foraminfers of
the lowermost parts of the Lower Triassic, the presence of
their coeval assemblages of the Late Permian, Changhsingian
age in Jadar Block of NW Serbia, enables correlation
with many regions of the Palaeotethys: e.g., in western
Slovenia, northeastern Hungary, northern Italy, northwestern
Caucasus, Turkey, Transcaucasia, and South China. The pre-
sent study can be added to the list of well-known and impor-
tant localities of the PTB interval; the results may contribute
to improve the precision of the Tethys-wide and even world-
wide correlation of the boundary events.
• Geochemical investigations undertaken for the first time in
the region as well as from all of Serbia, show that stable
isotopes (C, N, S), mineralogy, major and trace elements of
the studied PTB interval section have similar patterns of
secular variation as in other well known marine Upper
Permian sections, suggesting major changes in sediment
provenance and marine environmental conditions prior to
the Lower Triassic, where geochemical proxies indicate
prolonged seawater anoxia.
• Geochemical changes of the Sitarička Glavica PTB sedi-
ments indicate a moderate degree of chemical weathering of
the parent material with no marked changes up the section
and an arid to semi-arid climate at the source. The Upper
Permian sediments are perhaps slightly more mature, and
there is a suggestion of a wetter phase around the PT boun-
dary at the time of large lakes in northern Pangea. Until just
above the PT boundary at + 4 meters, suboxic conditions
seem to have dominated, than conditions became predomi-
nantly oxic, but the various redox proxies do not correlate
well.
Acknowledgments: We are very grateful to Merlynd K. Nestell
(University of Texas at Arlington) for the identifications of
fusulinacean species and checking English. Communication
and discussion on conodonts with Charles M. Henderson
(Calgary, Canada) are acknowledged. The study was partly
supported by the Slovenian Research Agency (programme
P1-0011). This paper is a contribution to IGCP 630, and to the
bilateral project cooperation between Serbian and Slovenian
Academies of Sciences and Arts (Project F-12). The research
of the authors from Serbia was supported by the Ministry of
Education, Science and Technical Development of the Republic
of Serbia (Project ON-176015). The critical comments and
helpful suggestions of two reviewers, Zhong-Quing Chen
(Wuhan, China) and Ian Metcalfe (Armidale, Australia),
helped to improve the quality of the paper and are gratefully
acknowledged.
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