ACTA PALAEONTOLOGICA ROMANIAE V. 6 (2008), P. 203-215.
OLIGOCENE - LOWER MIOCENE EVENTS IN ROMANIAMihaela
MELINTE-DOBRINESCU1 & Titus BRUSTUR1Abstract. This paper is
focused on the biotical and lithological markers, which are present
in the Eastern Carpathians and in NW Transylvania, and allows
correlation of the Oligocene-Lower Miocene deposits of these two
regions. In the both above-mentioned areas, the debut of the
Oligocene is characterized by the instauration of an anoxic/hypoxic
regime, related to the paleogeographic changes of those times
(i.e., the first isolation of the Paratethys from Mediterranean).
This event is marked by the appearance of endemic (Paratethyan)
nannofloras in the Carpathian and Transylvanian areas, accompanied
by endemic mollusc faunas, and slightly preceded by blooms of the
low-salinity nannofossil Braarudosphaera bigelowii. Within the
Early Oligocene interval, coccolithic laminitic limestones (Tylawa
type) were accumulated within the NP23 Calcareous Nannofloral Zone.
The Rupelian laminitic limestone contains bloom of endemic
Paratethyan nannofossils. During the Late Oligocene interval,
coccolithic laminitic limestones (Jaso type) were identified both
in the Eastern Carpathians and NW Transylvania, in the NP24
Calcareous Nannofossil Zone, and yielded blooms of cosmopolitan
nannofloral taxa. The youngest level of coccolithic laminitic
limestones (Zagrz type) was identified in uppermost Oligocene
deposits of the Eastern Carpathians (within the NP25 Calcareous
Nannofloral zone, Late Chattian in age), while in the Transylvanian
area this marker was not found so far. The Oligocene/Miocene
boundary (approximated by the first occurrence of the nannofossil
Sphenolithus capricornutus) is pointed out both in the Eastern
Carpathian and NW Transylvanian areas by a tuff level (placed
within the NN1 Calcareous Nannofossil Zone). Around the
Aquitanian/Burdigalian boundary (within the NN2 Calcareous
Nannoplankton Zone), another tuff level was deposited in the
southern and central regions of the Eastern Carpathians. Key words.
Oligocene-Lower Miocene; lithology; bio-events; Eastern
Carpathians; NW Transylvania.
INTRODUCTION The Oligocene is associated with a climatic
deterioration (Aubry, 1992), expressed by an overall significant
temperature decrease (Zachos et al., 2001), and by the instauration
of ice caps in the Antarctic region. These changes are accompanied
by a major sealevel fall, according to Haq et al., 1988 (Fig.1),
concomitantly with a global ocean-land reorganization (Scotese,
2002). Additionally, the very active tectonic regime of the
Oligocene interval led to important paleogeographic modifications:
the Tethys Ocean was divided, in the European regions, in two main
branches (i.e., the Mediterranean and the Paratethys - Bldi, 1980;
Rusu, 1988; Sndulescu & Micu, 1989; Rgl, 1998).
Becoming isolated from the Mediterranean, the Paratethys domain
displayed a distinct paleobiogeography, hydrological regime, and
sedimentation dynamic. Therefore, the stratigraphers use regional
stages for the two main Paratethys branches, including for the
Central Paratethys (Cicha et al., 1998, Fig. 2) where the present
Romanian territory was located (Mszros, 1989; Rusu, 1989, Rgl,
1999, among many others). Around the Eocene/Oligocene boundary
interval, the termohaline water stratification and the primarily
estuarine water circulation pattern, eventually resulting in
recurrent episodes of stagnation, characterized the Paratethys
domain, leading to the accumulation of hypoxic to anoxic
sediments.
Fig. 1 Late Eocene-Early Miocene global climatic and sea-level
fluctuations (climatic events and average global temperature after
Zachos et al., 2001; sea-level after Haq et al., 1988).
1
National Institute of Marine Geology and Geo-ecology, Street
Dimitrie Onciul, No. 23-25, RO-024053, Bucharest, Romania, e-mail:
[email protected], [email protected]
M. MELINTE-DOBRINESCU & T. BRUSTUR
Fig. 2 Correlation of global stages with the central Paratethys
stages, and with the foraminiferal and calcareous nannoplankton
biozones (modified after Berggren et al., 1995 and Cicha et al.,
1998). PPaleogene Foraminiferal Zones; M-Miocene Foraminiferal
Zones; NP-Paleogene Calcareous Nannoplankon Zones; NN-Neogene
Calcareous Nannoplankton Zones. Such type of deposition prevailed
during the whole Oligocene and Lower Miocene times, and is referred
as the menilite and dysodile facies in the Central Paratethys,
including Romania (for a synthesis see Popescu et al., 1995 and
Rusu et al., 1996). Intervals of high productivity water surface
allow the accumulation of several levels of coccolithic laminitic
limestones in the whole Central Paratethys (fide Uhlig, 1883;
Nowak, 1965; Haczewski, 1981, 1989; Nagymarosy & Voronina,
1992; Krhovsk et al., 1992; vbenick et al., 2007), including
Romania (Grasu et al., 1982; Alexandrescu & Brustur, 1985;
Ionesi, 1986; Brustur & Alexandrescu, 1989; tefnescu et al.,
1989; Melinte, 2005). The Oligocene coccolithic laminitic
limestones represent excellent lithological markers, very useful
for correlations in the whole Carpathian area. During the Oligocene
- Lower Miocene, tuff levels are also known to occur in different
areas from Romania; hence, they could be regarded as lithological
markers, useful for regional correlations. The aim of this paper is
to reveal the lithological and paleobiological markers, which could
be valuable for Oligocene-Lower Miocene stratigraphical
correlation. Two Romanian regions were mainly investigated (i.e.,
the NW Transylvania, namely the Preluca sedimentation area, and the
central-southern part of the Eastern Carpathians) (Fig. 3).
GEOLOGICAL SETTING NW Transylvania In the NW Transylvania, three
distinct Paleogene sedimentation areas (Gilu, Mese and Preluca)
were distinguished (Rusu, 1970). In particular, the Preluca area
displays a continuous marine sedimentation within the
Oligocene-Early Miocene interval. Hence, the Early Oligocene is
marked by the deposition of the Cuciulat Formation, mainly composed
of grey and brown marlstones and claystones, followed by the
bituminous marls of the Bizua Formation and the bituminous shales
of the Ileanda Formation (Fig. 4). The Late Oligocene interval is
characterized by the sedimentation of the Buza Formation, mainly
made by an alternance of sandstones and marls, and by the younger
lutite, hemipelagic Vima Formation. Towards NE, the Vima Formation
progressively replaced the Buza Formation. The Oligocene/Miocene
boundary (the boundary between the NP25/NN1 Calcareous
Nannoplankton Zone of Martini, 1971) was previously identified,
based on calcareous nannofossil assemblages, in the Vima formation
(Mszros et al., 1979; Mszros & Ianoliu, 1989; Rusu et al.,
1996).
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OLIGOCENE-LOWER MIOCENE EVENTS IN ROMANIA
Fig. 3 Location of the Oligocene-Lower Miocene studied sections
in the NW Transylvania and in the central and southern part of the
Eastern Carpathians. Eastern Carpathians The Oligocene-Lower
Miocene sediments crop out on large areas in the Eastern
Carpathians, belonging to (1) the sedimentary cover of the Moldavid
Nappes (Outer Flysch Zone), (2) the post-tectonic cover of the
Outer Dacid Nappes, and (3) the Pienid tectonic units (Sndulescu,
1984). Within the Moldavids, in the outer (eastern) part of the
central and southern Eastern Carpathians, the OligoceneLower
Miocene formations are involved in the Tarcu, Marginal Fold and
Subcarpathian nappes, where they display two main lithofacies,
namely the Bituminous Kliwa Facies in the external part and the
FusaruPucioasa Facies (similar to the Polish Carpathian Krosno
facies), in the inner part Sndulescu & Micu, 1989. During the
Paleogene, varying rates of subsidence were recorded in the
Moldavids (tefnescu & Melinte, 1996). The subsidence was faster
in the Eocene, Late Oligocene and Early Miocene, when mostly
terrigenous rocks (flysch and molasses deposits) accumulated, and
lower within the Late Eocene-Early Oligocene interval, when a
pelagic sedimentation prevailed. The Early Oligocene interval (=
the Rupelian stage) is characterized in both lithofacies by the
deposition of the Lower Dysodile Shale Formation, composed of
bituminous shales with frequent sulphur and disarticulated fish
remains (Fig. 5). In the eastern (outermost) Kliwa Facies, the base
of the Oligocene is characterized by the sedimentation of the Lower
Menilite Formation, consisting of cherts and bituminous marls,
followed by the Lower Dysodile Shale Formation, composed of
bituminous shales. During Late Oligocene times (= the Chattian
stage), in the inner Fusaru-Pucioasa lithofacies, turbiditic
sequences made by calcareous sandstones interbedded with bituminous
marls, as well as green and gray pelites, occur. Within the outer
lithofacies, the same interval consists of the Kliwa Sandstone
Formation, including white massive, orthoquartzitic sandstones
interlayered with thin bituminous shales. Around the
Oligocene/Miocene boundary interval, shaly turbidites were
deposited, namely the Vinetiu Formation in the inner facies, and
the Podu Morii Formation in the outer facies (the later unit shows
in addition prominent convolute sandstones). The Oligocene/Miocene
boundary was identified, based on calcareous nannoplankton
investigations, towards the base of the two above-mentioned units
(Melinte, 1988; Ionesi & Mszros, 1989; Micu et al., 1989;
Ionesi et al., 1998; Mruneanu, 1999; Melinte et al., 1999; Melinte,
2005), within the NN1 Nannofossil Zone of Martini (1971) Fig.
5.
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M. MELINTE-DOBRINESCU & T. BRUSTUR
Fig. 4 Lithology and main biotical events recorded in the
Preluca area, NW Transylvania (modified after Rusu, Popescu &
Melinte, 1996).
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OLIGOCENE-LOWER MIOCENE EVENTS IN ROMANIA
Fig. 5 Lithology and main biotical events recorded in the
central and southern part of the Eastern Carpathians (modified
after Melinte, 2005). LITHOLOGICAL AND BIOTICAL MARKERS Early
Oligocene The restricted Early Oligocene circulation of the
Paratethys realm, which led to the instauration of a hypoxic to
anoxic regime, is mirrored in the sedimentation of both the NW
Transylvania and Eastern Carpathian regions. There, the bituminous
marls and shales of the Bizua and Ileanda units (in NW
Transylvania), as well as the bituminous cherts, marls and shales
of the Menilite and Lower Dysodile formations (in the Eastern
Carpathians) were deposited within the Rupelian (=Early Kiscellian
interval). The initiation of the anoxic sedimentation is reflected
in the calcareous nannoplankton fluctuation. The cosmopolitan
Eocene nannofossils are sharply replaced by endemic taxa. The five
Early Rupelian nannofloral extinctions of Discoaster saipanens
Bramlette & Riedel, D. barbadienis Tan, Clausicoccus
subdistichus (Roth & Hay) Prins, Discoaster tanii (Bramlette
& Riedel) Bukry and Helicosphaera reticulata Bramlette &
Wilcoxon are followed by another seven extinctions in the upper
Rupelian (NP23 Nannofossil Zone), when Isthmolithus recurvus
Deflandre, Reticulofenestra hillae Bukry & Percival, R.
umbilica (Levin) Martin & Ritzowski, Orthozygus aureus
(Stradner) Brameltte & Wilcoxon, Lanternitus minutus Stradner,
Chiasmolithus oamaruensis (Deflandre) Hay, Mohler & Wade and
Transversopontis fibula Ghea disappeared (Figs. 4, 5). Between
these two groups of extinctions, at the end of the early Rupelian
(in NP23a Nannofossil Subzone of Melinte, 1995), the endemic
nannofossils Reticulofenestra lockeri Mller, R. ornata Mller,
Transversopontis fibula Ghea and T. latus Mller appeared (Pl. 1).
The succession of these nannofloral events were recorded in all the
sections investigated from the NW Transylvania, as well as from the
central and southern part of the Eastern Carpathians. Moreover,
these bioevents could be recognized everywhere in Romania (i.e., in
the Getic Depression, according to Roban & Melinte, 2006),
where continuous Early Oligocene rock-sequences crop out. In NW
Transylvania, a distinct bio-horizon with the endemic Paratethyan
macrofaunal taxa Cardium lipoldi and Janschinella garetzkii is
present, towards the base of the Bizua Formation (Rusu, 1988; Rusu
et al., 1996), within the lower part of the NP23 Nannofossil Zone.
The Janschinella garetzkii bio-horizon is present also in the
Eastern Carpathians, towards the base of the Lower Dysodile
Formation, in the same stratigraphic position (i.e., Lower
Rupelian), according to Rusu (1999). Remarkably, synchronously with
the occurrence of the Janschinella garetzkii macrofaunal level,
monospecific calcareous nannoplankton assemblages, with
Braarudosphaera bigelowii (Gran & Braarud)
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M. MELINTE-DOBRINESCU & T. BRUSTUR
Deflandre, was identified in the investigated NW Transylvanian
region. In several sections from the Preluca area of NW
Transylvania (the better exposure being located in the Poienii
Valley, the Fntnele Village Fig. 4) several cm coccolithic
laminitic limestones (Coccolithic limestone 1) occur, within the
lower part of the bituminous shales of the Ileanda Formation
(around the boundary of the NP23a/b Calcareous Nannofossil Subzones
of Melinte, 1995). In the whole Eastern Carpathian bend,
coccolithic laminitic limestones are present towards the base of
the Lower Dysodile Formation, yielding also a Rupelian age (Fig.
5). Both in the NW Transylvania and in the Eastern Carpathians, the
laminas of the Rupelian limestone are made by blooms of the endemic
Paratethyan nannofossils, such as Reticulofenestra ornata, R.
lockeri and Transversopontis fibula (Pl. 1). Below the Early/Late
Oligocene boundary (= the Rupelian/Chattian boundary, placed in the
NP24 Calcareous Nannofossil Zone according to Berggren et al.,
1995) the endemic Paratethyan nannofossils vanished, and new
cosmopolitan taxa (Young, 1998), such as Sphenolithus ciperoensis
Bramllete & Wilcoxon and Chiasmolithus altus Bukry and
Percival, appeared (Figs. 4 and 5). Synchronously, the pelitic
anoxic sedimentation is replaced by sandy-shaly turbidites in the
Eastern Carpathians (with more frequent bituminous rocks in the
outer facies), and by sandstones and clays in the NW Transylvanian
area. Late Oligocene The Late Oligocene (Chattian=Late Kiscellian
and Early Egerian) is an interval characterized by cosmopolitan
nannofloral assemblages in both the Preluca sedimentation area (NW
Transylvania) and in the Eastern Carpathians. In fact, the
nannoplankton zones of Martini (1971), completed with the Subzones
of Melinte (1995) could be recognized in all the Upper Oligocene
succesions from Romania (Figs. 4 and 5). In the both inner and
outer Oligocene facies of the Eastern Carpathians, a coccolithic
laminitic limestone (Coccolithic limestone 2) was deposited.
Several cm to dm intercalations of this limestone could be observed
from the northern part of the Eastern Carpathians until the bend
area, in the Pucioasa-Fusaru Formation and in its outer equivalent,
the Lower Kliwa Sandstone Formation (Fig. 5). The Lower Chattian
laminitic limestone (placed in the NP24 Calcareous nannofossil
Zone) contains, in its laminas, bloom of cosmopolitan
nannoplankton
species, such as Dictyococcites bisectus (Hay, Mohler &
Wade) Bukry & Percival, Zygrhablithus bijugatus (Deflandre)
Deflandre, Cyclicargolithus floridanus (Roth & Hay) Bukry and
Sphenolithus moriformis (Brnnimann & Stradner) Bramlette &
Wilcoxon (Pl.1). The Lower Chattian laminitic limestone
(Coccolithic limestone 2) is also present in the NW Transylvanian
area (Rusu et al., 1996), placed in the Buza Formation (one of the
best section where it is exposed is the Runcului Valley, Fig. 4).
The nannofloral assemblages observed in the white laminas of this
limestone are similar with those from the Eastern Carpathians and
belong also to the NP 24 Calcareous Nannoplankton Zone. Besides
Lower Chattian coccolithic laminitic limestone identified in thr
both NW Transylvanian and in the Eastern Carpathian regions,
another Chattian distinct level of coccolithic laminitic limestones
(Coccolithic limestone 3) was observed only in the Eastern
Carpathian bend. This is placed din the NP 25a Calcareous
Nannoplankton Subzone, between the first occurrence of Pontosphaera
enormis (Locker) Perch-Nielsen and the first occurrence of
Triquetrorhabdulus carinatus Martini, being Late Chattian in age
(Fig. 5). Below the Coccolithic limestone 3, towards the Oligocene
top (in the latest Chattian) a high abundance of the calcareous
nannoplankton Sphenolithus and Discoaster genera was observed in
the nannofloral assemblages. The two above-mentioned genera jointly
amount to almost 50% of the total recorded nannofloras. This event
was recognized only in the Eastern Carpathians, within the upper
part of the Pucioasa-Fusaru, and respectively in the Lower Kliwa
Sandstone formations. Early Miocene The Oligocene/Miocene boundary
was recognized both in the NW Transylvania and Eastern Carpathians
based on calcareous nannofossil assemblages. This boundary is
placed within the NN1 Calcareous Nannofossil Zone (Berggren et al.,
1995), and it is approximated by the first occurrence (FO) of
Sphenolithus capricornutus Bukry and Percival. Based on this
bio-event we placed the Oligocene/Miocene boundary in the Eastern
Carpathians towards the lower part of the Vineiu Formation (in the
inner facies), and within the lower part of the Podu Morii
Formation (within the outer facies) (Fig. 5). Just above the FO of
Sphenolithus capricornutus, a thin cm level of green tuff,
described by tefnescu et al. (1989) as the Vineiu Tuff, was
observed in the both
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OLIGOCENE-LOWER MIOCENE EVENTS IN ROMANIA
Oligocene facies of the Eastern Carpathians. This tuff is
synchronous with the tuff observed in the NW Transylvania, the
Valea Cocii Tuff, well preserved in the Cocii Valley (Mgoaja
Village). A younger tuff level (a 50 cm white tuff, described as
the Mlcile Tuff by tefnescu et al., 1989, and as the Vlenii de
Munte Tuff by Alexandrescu et al., 1994) is present in the Eastern
Carpathians (very well exposed in the southern part, between the
Buzu and Teleajen valleys) and also in northern sectors (i.e., the
Trotu Valley at Trgu-Ocna, Alexandrescu & Brustur, 1996). This
tuff is placed around the Aquitanian/Burdigalian boundary, shortly
above the FO of Reticulofenestra pseudoumbilicus Gartner (< than
7 m), within the NN2 Calcareous Nannofossil Zone. In the Trotu
Valley basin, tuff and bentonites were identified in the Upper
Dysodile Formation of the Kliwa Sandstone Facies (Alexandrescu
& Brustur, 1996). Several thin cm up to dm tuff levels were
identified by the above-mentioned authors, who described them as
the Livadea bentonites. Notably, towards the top of the Upper
Dysodile Formation, within the Early Burdigalian. a thicker tuff
(3-4m) was observed, being described as the Falcu Tuff
(Alexandrescu & Brustur, 1996). DISCUSSION Several levels of
coccolithic laminitic limestones were identified in the NW
Carpathians and Eastern Carpathian regions. We described herein
these limestones as Coccolithic limestones, and they could be
correlated (as age and lithology) with those described in other
Carpathian areas (in particular in the Polish Carpathians
Haczewski, 1981; 1989) as follows: Coccolithic limestone 1 the
Tylawa Limestone (Rupelian in age), Coccolithic limestone 2 the
Jaso Limestone (Early Chattian in age), and Coccolithic limestone 3
- the Zagrz Limestone (Late Chattian in age). Even if these
coccolithic limestones were sedimented during different
paleogeographical settings, their deposition is probably due to
similar paleonevironmental conditions, related to a high nutrient
input and absence of other planktonic competitors (i.e.,
foraminifers) than the calcareous nannoplankton. The Coccolithic
limestone 1 (= the Tylawa limestone) was deposited during the first
isolation of the Paratethys from the Mediterranean (the NP 23
Calcareous Nannoplankton Zone), fact argued by the presence of
endemic nannofloras. Moreover, the occurrence of nannofloral
monospecific assemblages with
Braarudosphaera bigelowii (which blooms are related to low
salinity surface waters Lamolda et al., 2005 and cooler waters
Siesser et al., 1992) indicates an important shift of salinity, and
probably a temperature decrease. Notably, Rupelian blooms of
Braarudosphaera bigelowii were also recorded in other Carpathian
areas (Krhovsk et al., 1992; Nagymarosy & Voronina, 1992). The
occurrence of the Coccolithic limestone 2 (= the Jaso Limestone) in
the whole Paratethys area, including the present Romanian
territory, is related to the restoration of the communication
between the Paratethys and the Mediterranean, within Late Oligocene
(= Chattian) times, in the NP24 Calcareous Nannoplankton Zone
respectively. It is to assumed that similar paleogeographic
conditions lasted in the upper part of the Chattian, when the
youngest Oligocene laminitic limestone, Coccolithic limestone 3 (=
the Zagrz Limestone), was sedimented, in the NP25 Calcareous
Nannoplankton Zone. Remarkably, both Chattian laminitic limestones
(i.e., Jaso and Zagrz) yielded blooms of cosmopolitan nannofossils.
Such blooms, of Dictyococcites bisectus, Zygrhablithus bijugatus,
Cyclicargolithus floridanus and Sphenolithus moriformis were
recorded in the whole Carpathian area in the above-mentioned
nannoplankton zones, even in the absence of the laminitic
limestones (Bubk, M., 1987; vbenick et al., 2007). Consequently,
the nannoplankton blooms are important Upper Oligocene
biostratigraphical horizons, and could be used for Paratethys
correlation. Between the depositional intervals of the Coccolithic
limestone 2 and 3 (Jaso and Zagrz respectively), a bloom of the
sphenoliths and discoasters, nannofossils related to an open marine
setting and warm surface temperature (Aubry, 1992; Fornaciari &
Rio, 1996), was identified. This nannofloral event could regionally
expressed the global Late Oligocene Warming Event (Zachos et al.,
2001), synchronous with the sea-level rise (Fig. 6). Taking into
account the Oligocene nannofloral fluctuation pattern, we may
assume that the Early Oligocene was characterized in the both
studied Romanian areas by a significant cooling, followed by an
increase of the temperature in Late Oligocene (Chattian) times. A
similar paleoclimatic scenario was hypothesized, based on
palynological evidence, by Olaru (1989). The above-mentioned author
reported an important temperature shift at the base of the
Oligocene, based on the presence of Arctic Tertiary
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M. MELINTE-DOBRINESCU & T. BRUSTUR
Fig. 6 Main Oligocene-Lower Miocene lithological and biotical
(calcareous nannofossil) markers of the NW Transylvanian and
Eastern Carpathian regions. angiosperms, followed by a slight
climatic warming in the depositional interval of the Fusaru, and
respectively Kliwa Sandstone of the Eastern Carpathians. Tuff and
bentonites are well-known in the Oligocene-Lower Miocene sediments
of the Eastern Carpathians, from the northern boundary of Romania
up to Carpathian bend area (Mutihac & Ionesi, 1973; Catan et
al., 1982; Mrza & Voiculescu, 1991). In particular, in the
Moldavid tectonic units, thin cm tuff and bentonites occur in the
Early Oligocene (Rupelian) Lower Menilite and Lower Dysodile
formations, as well as in the Early Miocene (Burdigalian) Upper
Menilite and Upper Dysodile lithological units (Alexandrescu et
al., 1984, 1991; tefnescu et al., 1989), and may represent,
regionally, useful lithological markers. Another tuff level is the
Vineiu tuff, identified in the both Moldavid facies,
Pucioasa-Fusaru and Lower Kliwa Sandstone (tefnescu et al., 1989).
This green tuff, 2530 cm in thickness, occurs slightly above the
Oligocene/Miocene boundary (above the first occurrence of the
nannofossil Sphenolithus capricornutus, according to Melinte, 1988,
2005), and it is synchronous with the Valea Cocci tuff deposited in
the NW Transylvania (Preluca sedimentation area). Another reliable
event is the deposition of the 40-50 cm in thickness white Mlcile
Tuff, which could be a good marker to emphasize the Burdigalian
base, at least in the southern and central parts of the Eastern
Carpathians. SUMMARY The investigation of the Oligocene-Lower
Miocene sediments of the NW Transylvania (Preluca sedimentation
area) and of the Eastern Carpathians allows us to recognize
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OLIGOCENE-LOWER MIOCENE EVENTS IN ROMANIA
several events, which are, in the stratigraphical succession,
the following (Fig. 6): - The anoxic/hypoxic deposition, which
marks the debut of the Oligocene; The presence of monospecific
assemblages with Braarudosphaera bigelowii, within the Rupelian
(Early Kiscellian), around the base of the NP23 Calcareous
Nannoplankton Zone; - The appearance of the endemic Paratethyan
nannofloras, synchronously with the occurrence of the Paratethys
macrofaunal bio-horizon with Cardium lipoldi and Janschinella
garetzkii, also in the NP23 Calcareous Nannoplankton Zone; - The
deposition, in the Late Rupelian (Early Kiscellian), of the
Coccolithic limestone 1 (the Tylawa Limestone), which contains
blooms of endemic nannofossils, within the upper part of NP23
Calcareous Nannofossil Zone; - The extinction of the endemic
Paratethys nannofloras around the top of the NP 23 Calcareous
Nannofossil Zone;
- The deposition, in the Early Chattian (Late Kiscellian), of
the Coccolithic limestone 2 (the Jaso Limestone), which contains
blooms of cosmopolitan nannofossils, within the NP24 Calcareous
Nannofossil Zone; - The occurrence of the Sphenolithus spp. and
Discoaster spp. nannofossil blooms; - The deposition, in the Late
Chattian (the top of the Kiscellian), of the Coccolithic limestone
3 (the Zagrz Limestone), which contains blooms of cosmopolitan
nannofossils, within NP25 Calcareous Nannofossil Zone; - The FO of
the nannofossil Sphenolithus capricornutus, which approximates the
Oligocene/Miocene boundary (Early Egerian); - The deposition of a
tuff (referred as the Vineiu Tuff in the Eastern Carpathians and
the Valea Cocii Tuff in the NW Transylvania), slightly above the
Oligocene/Miocene boundary, in the NN1 Calcareous Nannoplankton
Zone; - The deposition of the Mlcile Tuff in the Eastern
Carpathians, around the base of the Burdigalian (in the
Eggenburgian), within the NN2 Calcareous Nannoplankton Zone.
REFERENCESAlexandrescu, Gr., Brustur, T., 1985. Les calcaires de
Jaslo des parties centrale et nord des Carpathes Orientales et leur
valeur stratigraphique. Dri de Seam ale Institutului de Geologie i
Geofizic 49, 173 186. Alexandrescu, Gr., Brustur, T., 1996. Roches
dorigine pyroclastique de lOligocne suprieure-Miocne infrieure de
la valle du Trotu (Carpathes Orientale). Studii i Cercetri de
Geologie 41, 3-15. Alexandrescu, Gr., Frunzescu, D., Brustur T.,
1994. The Vlenii de Munte Tuff petrographic and stratigraphic
significance. Studii i Cercetri de Geologie 39, 51-57.
Alexandrescu, Gr., Brustur, T., Matei, V., Antonescu, A., 1984.
Asupra unor cinerite din partea central si nordic a Carpailor
Orientali. Dri de Seam ale Institutului de Geologie i Geofizic
LXVIII, 4, 69-90. Alexandrescu, Gr., Brustur, T., Nica, M., Urcan,
T., Enache, Gh., 1991. Bentonitic clays from the lower Oligocene at
Trgu-Ocna (East Carpathians). In: Petrescu, I. (Ed.), The Oligocene
from the Transylvanian Basin, Romania. University of Cluj-Napoca,
Geology-Mineralogy Department, Special Issue, Cluj-Napoca, 331-341.
Aubry, M.-P., 1992. Late Paleogene calcareous nannoplankton
evolution: a tale of climatic deterioration. In: Prothero, D.R.,
Berggren, W.A. (Eds), Eocene-Oligocene Climatic and Biotic
Evolution, Princeton University Press, 272-309. Bldi, T., 1980. The
early history of the Paratethys. Bulletin of Hungarian Geological
Society 110, 456472. Berggren, W.A., Kent, D.V., Swisher, CC.,
Aubry, M.P., 1995. A revised Cenozoic geochronology and
chronostratigraphy. Society of Economics Paleontologists and
Mineralogists Special Publication 54, 129212. Brustur, T.,
Alexandrescu, Gr., 1989. Dbris de plantes fossiles dans les
calcaires de Jaslo des valles de Buzu et Teleajen (Carpathes
Orientales). In: Petrescu, I. (Ed.), The Oligocene from the
Transylvanian Basin, Romania. University of Cluj-Napoca,
Geology-Mineralogy Department, Special Issue, Cluj-Napoca, 241-248.
Bubk, M., 1987. Oligocene calcareous nannoplankton of the Menilitic
Formation with the Jaslo Limestone horizon from Bystice nad Ol (the
Subsilesian Unit, the West Carpathians). Knihovnika ZPN 6b,
Miscellanea Micropalaeontologica II/2, 45-57 (in Czech with English
Summary). Catan, C., Grasu, C., Stamate, I., 1982. Considrations
sur certaines bentonites, tufs et tufites bentonitiss de lOligocne
de lUnit de Vrancea (Carpates Orientales). Analele iinifice ale
Universitii Alexandru Ioan Cuza Iai, seciunea IIb,
GeologieGeografie 28, 11-15. Cicha, I., Rgl F., Rupp, Ch., tyrok,
J., 1998. Oligocene-Miocene foraminifera of the Central Paratethys.
Abhandlungen der
211
M. MELINTE-DOBRINESCU & T. BRUSTUR
Senckenbergischen Nat urforschenden Gesellschaft 549, 1-325.
Fornaciari, E., Rio, D., 1996. Latest Oligocene to early middle
Miocene quantitative nannofossil biostratigraphy in the
Mediterranean region. Micropaleontology 42, 136. Haczewski, G.,
1981. Extent and lateral variation of individual turbidites in
Flysch, horizons with Jaso limestones, Krosno beds, Polish
Carpathians. Studia Geologica Polonica LXVIII, 13-27. Haczewski,
G., 1989. Coccolith limestone horizons in the Menilite-Krosno
series (Oligocene Carpathians)- identification, correlation and
origin. Annales Societatis Geologorum Poloniae 59, 435-523 (in
Polish with English Summary). Haq, B.U., Hardenbol, J., Vail, P.R.,
1988. Mesozoic and Cenozoic chronostratigraphy and cycles of
sea-level change. In: Wilgus, C.K., Hastings, B.S., Posamentier,
H., van Wagoner, J., Ross, C.A., Kendall, C.G. (Eds.), Sea-level
Changes: an Integrated Approach. Society of Economic
Paleontologists and Mineralogists Special Publication 42, 71-108.
Grasu, C., Apetroaiei, N., Florea, F., 1982. Considrations
ptrognetiques sur les calcaires de Jaslo du Flysch des Carpates
Orientales. Analele iinifice ale Universitii Alexandru Ioan Cuza
Iai, seciunea IIb, Geologie-Geografie 28, 5-10. Ionesi, L., 1986.
Signification lithostratigraphique du calcaire de Jaslo dans le
flysch externe carpatique. Analele iinifice ale Universitii
Alexandru Ioan Cuza Iai, seciunea IIb, Geologie-Geografie 32, 1722.
Ionesi, L., Mszros, N., 1989. Sur la limite Oligocne-Miocne dans le
flysch externe Carpatique. In: Petrescu, I. (Ed.), The Oligocene
from the Transylvanian Basin, Romania. University of Cluj-Napoca,
Geology-Mineralogy Department, Special Issue, Cluj-Napoca, 133-141.
Ionesi, L., Bogatu, L., Melinte, M., 1998. Limita Oligocen/Miocen n
Pnza de Vrancea (semifereastra Sucevia). Revista Minelor 6, 24-29.
Krhovsk, J., Adamov, M., Hladkov, J., Maslowsk, H., 1992.
Paleoenvironmental changes across the Eocene/Oligocene boundaryin
the dnice and Pouzdany units (Western Carpathians, Czechoslovakia):
the long-term trend and orbitally forced changes in calcareous
nannofossil assemblages. In: Hamrmd, B. & Young, J. (Eds.),
Nannoplankton Research. Proceedings of the Fourth INA Conference,
Prague 1991, Vol. II: Tertiary Biostratigraphy and Paleoecology;
Quaternary coccoliths. Knihovnika ZPN 14b, 105-187. Lamolda, M.A.,
Melinte, M.C., Kaiho, K., 2005. Nannofloral extinction and
survivorship across the K/T boundary at Caravaca, southeastern
Spain. Palaeogeography, Palaeoclimatology, Palaeoecology 224,
2752.
Martini, E., 1971: Standard Tertiary and Quaternary calcareous
nannoplankton zonation. In: Farinacci A. (Ed.), Proceedings of the
Second Planktonic Conference Roma 1970. Edizioni Tecnoscienza,
Roma, 2, 739785. Mruneanu, M., 1999. Litho- and biostratigraphy
(calcareous nannoplankton) of the Miocene deposits from the Outer
Moldavides. Geologica Carpathica 50, 4, 313-324. Mrza, I.,
Voiculescu, D., 1991. poques volcanoclastiques sur le territoire de
la Roumanie. In: Bedelean, I., Ghergari, L., Mrza, I., Mszros, M.,
Nicorici, E. & Petrescu, I. (Eds.), The volcanic tuffs from the
Transylvanian Basin, Romania. University of Cluj Napoca, 23-37.
Melinte, M., 1988. Stabilirea limitei Oligocen/Miocen n bazinul
Vaii Buzului, pe baza nannoplanctonului calcaros. Romanian Journal
of Stratigraphy 75/4, 91-97. Melinte, M., 1995. Changes in
nannofossil assemblages during the Oligocene-Lower Miocene interval
in the East Carpathians and Transylvania. Romanian Journal of
Stratigraphy, 76, suppl.7, 171172. Melinte, M., Popescu, G., Rusu,
A., Constantin, P., 1999. Lito- si biostratigrafia depozitelor
oligocen-miocen inferioare dintre vile Trotu i Bistria. Anuarul
Institutului Geologic al Romniei 71, 39-52. Melinte, M.C., 2005.
Oligocene palaeoenvironmental changes in the Romanian Carpathians,
revealed by calcareous nannofossil fluctuation. In: Tyszka, J.,
Oliwkiewicz-Miklasinska, M., Gedl, P. & Kaminski, M.A. (Eds.),
Methods and Application in Micropalaeontology. Studia Geologica
Polonica, 124, 15-27. Mszros, N., 1989. Delimitation et
subdivisions de lOligocne en Europe et leur application differentes
rgions de la Roumanie. In: Petrescu, I. (Ed.), The Oligocene from
the Transylvanian Basin, Romania. University of Cluj-Napoca,
Geology-Mineralogy Department, Special Issue, Cluj-Napoca, 717.
Mszros, N., Ianoliu, C., 1989. Nannoplankton zones in the Oligocene
deposits of the NW Transylvanian Basin. In: Petrescu, I. (Ed.), The
Oligocene from the Transylvanian Basin, Romania. University of
Cluj-Napoca, Geology-Mineralogy Department, Special Issue,
Cluj-Napoca, 157-162. Mszros, N., Ghea, N., Ianoliu, C., 1979.
Nannoplankton zones in the Paleogene deposits of the Transylvanian
basin. Studii i Comunicri 23, 73-80. Micu, M., Melinte, M.,
Constantin, P., 1989. Podu Morii Beds in the Tazlul Srat Basin.
Romanian Journal of Stratigraphy 75/4, 97101. Mutihac, V., Ionesi,
L., 1973. Geologia Romniei. Editura Tehnic Bucureti, 646 pp. Nowak,
W., 1965. Sur lorigine organique des calcaires de Jaslo des couches
mnilitiques et de Krosno dans les Carpates flyscheuses (Oligocne).
Carpatho-Balkan Geological
212
OLIGOCENE-LOWER MIOCENE EVENTS IN ROMANIA
Association, Congress VII Sofia, Reports II, 287-290.
Nagymarosy, A., Voronina, A.A. 1992. Calcareous nannoplankton from
the Lower Maykopian beds (Early Oligocene, Union of Independent
States). In: Hamrmd B. & Young J. (Eds.), Nannoplankton
Research. Proceedings of the Fourth INA Conference, Prague 1991,
Vol. II Tertiary Biostratigraphy and Paleoecology; Quaternary
coccoliths. Knihovnika ZPN 14b, 189-221. Olaru, L., 1989. Evolution
and adaptation of Oligocene paleoflora in the East Carpathians of
Romania. In: Petrescu, I. (Ed.), The Oligocene from the
Transylvanian Basin, Romania. University of Cluj-Napoca,
Geology-Mineralogy Department, Special Issue, Cluj-Napoca, 227-240.
Popescu, Gh., Rusu, A., Melinte, M.C., Pestrea, S., 1995. Field
Symposium Oligocene-Miocene transition and main geological events
in Romania. Romanian Journal of Stratigraphy 75, 1-65. Roban, R.,
Melinte, M.C., 2006. Paleogene lithoand biostratigraphy of the NE
Getic Depresssion. Acta Palaeontologioca Romaniae 5, 223-249. Rgl,
F., 1998. Palaeogeographic Consideration for Mediterranean and
Paratethys Seaways (Oligocene to Miocene). Annalen des
Naturhistorischen Museums in Wien 99A, 279-310. Rgl, F., 1999.
Mediterranean and Paratethys. Facts and Hypothesis of an Oligocene
to Miocene Paleogeography (Short Overview). Geologica Carpathica
50, 4, 339-349. Rusu, A., 1970. Corelarea faciesurilor Oligocenului
din regiunea Treznea-Bizua (nord-vestul Bazinului Transilvaniei).
Studii i Cercetri Geologice, Geofizice i Geografice, Seria Geologie
15/2, 513-525. Rusu, A., 1988. Oligocene events in Transylvania
(Romania) and the first separation of Paratethys. Dri de Seam ale
Institutului de Geologie i Geofizic 72/73, 207-223. Rusu, A., 1989.
Problems of correlation and nomenclature concerning the Oligocene
formations in NW Transylvania. In: Petrescu, I. (Ed.), The
Oligocene from the Transylvanian Basin, Romania. University of
Cluj-Napoca, Geology-Mineralogy Department, Special Issue,
Cluj-Napoca, 6779.
Rusu,
A., 1999. Rupelian mollusk fauna of Solenovian type found in
Eastern Carpathian (Romania). Acta Palaeontologica Romaniae 2,
449-452. Rusu, A., Popescu, G., Melinte, M., 1996.
Oligocene-Miocene Transition and Main Geological Events in Romania.
Romanian Journal of Stratigraphy 76, suppl. 1, 56 pp. Sndulescu,
M., 1984. Geotectonic of Romania (in Romanian). Editura Tehnic
Bucureti, 335 pp. Sndulescu, M., Micu, M., 1989. Oligocene
paleogeography of the East Carpathians. In: Petrescu, I. (Ed.), The
Oligocene from the Transylvanian Basin, Romania. University of
Cluj-Napoca, Geology-Mineralogy Department, Special Issue,
Cluj-Napoca, 79 86. Scotese, C.R., 2002. Paleo-Map website
(http.//www.Scotese.com). Siesser, W.G., Bralower, T.J., De Carlo,
E.H., 1992. Mid-Tertiary Braarudosphaera-rich sediments on the
Exmouth Plateau. In: von Rad, U., Haq, B. U., et al. (Eds.),
Proceedings of the Ocean Drilling Program, Scientific Results 122,
653-663. tefnescu, M., Popescu, I., tefnescu, M., Melinte M., Ivan,
V., Stnescu, V., 1989. Aspects of the possibilities of the
lithological correlations of the Oligocene/Miocene Boundary in the
Buzu Valley. Romanian Journal of Stratigraphy 75/4, 83-91.
tefnescu, M., Melinte, M., 1996. Cretaceous-Early Miocene
subsidence and the related source and reservoir rocks in the
Moldavids. In: Wessly, G. & Liebl, W. (eds.), Oil and Gas in
Alpidic Thrustbelts and Basins of Central and Eastern Europe. EAPG
Special Publications 5, 197-204. vbenick, L., Bubk, M., Strnk, Z.,
2007. Biostratigraphy and paleoenvironmental changes on the
transition from the Menilite to Krosno lithofacies (Western
Carpathians, Czech Republic). Geologica Carpathica 58, 3, 237-262.
Zachos, J. C., Shackleton, N.J., Revenaugh, J.S., Plike, H.,
Flower, B.P., 2001. Climate response to orbital forcing across the
Oligocene/Miocene Boundary. Science 292, 274-278. Young, J.R. 1998.
Neogene. In: Bown, P.R. (Ed.), Calcareous nannofossil
biostratigraphy. British Micropalaeontological Society, London,
225-265.
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PLATE 1 LM, All the microphotographs are N+, except Figs. 12 and
20 which are in NII Fig. 1. Braarudosphaera bigelowii (Gran &
Braarud) Deflandre, Poienii Valley (Fntnele Village), Bizua
Formation, NP22 Biozone. Fig. 2. Reticulofenestra pseudoumbilicus
(Gartner), Buzu Valley, Podu Morii Formation, NN2 Biozone. Fig. 3.
Helicosphaera carteri (Wallich) Kamptner, Buzu Valley, Podu Morii
Formation, NN2 Biozone. Fig. 4. Sphenolithus moriformis (Brnnimann
& Stradner) Bramlette & Wilcoxon, Vineiu section, Pucioasa
Formation, NP 24 Biozone. Fig. 5. Bloom of Reticulofenestra ornata
Mller, Bsca Rozilei (Nehoiau), Tylawa Coccolithic Limestone, NP 23
Biozone. Fig. 6. Bloom of Dictyococcites bisectus (Hay, Mohler
& Wade) Bukry & Percival and Zygrhablithus bijugatus
(Deflandre) Deflandre, Vineiu section, Jaslo Coccolithic Limestone,
NP 24 Biozone. Fig. 7. Transversopontis fibula Gheta, Trgu-Ocna
Section, Lower Dysodilic Fomation, NP23 Biozone. Fig. 8.
Pontosphaera multipora (Kamptner) Roth and Braarudosphaera
bigelowii (Gran & Braarud) Deflandre, Trgu-Ocna Section, Lower
Menilite Formation, NP22 Biozone. Fig. 9. Reticulofenestra ornata
Mller, Trgu-Ocna Section, Lower Dysodilic Fomation, NP23 Biozone
Fig. 10. Reticulofenstra lockeri Mller, Trgu-Ocna Section, Lower
Dysodilic Fomation, NP23 Biozone. Fig.11. Pontosphaera enormis
(Locker) Perch-Nielsen, Runcului Valley (Poiana Blenchii), Buza
Formation, NP25 Biozone. Fig. 12. Discoaster barbadiensis Tan, Bsca
Rozilei Valley (at Nehoiau), Plopu Formation, NP21 Biozone. Fig.
13. Rhabdosphaera clavigera Murray & Blackman and small
reticulofenstrids, Cocii Valley (Mgoaja Village), Vima Formation,
NN1 Biozone. Fig. 14. Chiasmolithus altus Bukry & Percival,
Runcului Valley (Poiana Blenchii), Buza Formation, NP 24 Biozone.
Fig. 15 a, b. Sphenolithus ciperoensis Bramlette & Wilcoxon, a-
450, b-00; Buzu Valley, Podu Morii Formation, NP25 Biozone. Fig.
16. Sphenolithus capricornutus Bukry & Percival, Vineiu
section, Vineiu Formation, NN 1 Biozone. Fig. 17. Sphenolithus
conicus Deflandre and Sphenolithus belemnos Bramlette &
Wilcoxon, Buzu Valley, Podu Morii Formation, NN2 Biozone. Fig. 18.
Helicosphaera scissura Miller, Buzu Valley, Podu Morii Formation,
NN1 Biozone. Fig. 19. Discoaster deflandrei Bramlette & Riedel,
Vineiu section, Pucioasa Formation, NP 25 Biozone. Fig. 20.
Reticulofenstra umbilica (Levin) Martin & Ritzkowski, Poienii
Valley (Fntnele Village), Bizua Formation, NP23 Biozone, N II Fig.
21. Reticulofenstra umbilica (Levin) Martin & Ritzkowski,
Poienii Valley (Fntnele Village), Bizua Formation, NP23 Biozone, N
+.
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M. MELINTE-DOBRINESCU & T. BRUSTUR
PLATE I
215