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Find of Early Planktonic Foraminifers in the Triassic of the Crimea

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  • JSC «Rusgeology»

Abstract

The appearance of planktonic foraminifers is the most dramatic episode in the evolution of Protozoans and an important event in the development of the biosphere during the last 400 Ma. Data on initial stages of the development of planktonic foraminifers are far from being complete, which hampers reliable dating of their evolution [1, 3-5, 8, 9].
482
Doklady Earth Sciences, Vol. 390, No. 4, 2003, pp. 482–486. Translated from Doklady Akademii Nauk, Vol. 390, No. 1, 2003, pp. 79–84.
Original Russian Text Copyright © 2003 by Korchagin, Kuznetsova, Bragin.
English Translation Copyright © 2003 by
MAIK
Nauka
/Interperiodica” (Russia).
The appearance of planktonic foraminifers is the
most dramatic episode in the evolution of Protozoans
and an important event in the development of the bio-
sphere during the last 400 Ma. Data on initial stages of
the development of planktonic foraminifers are far
from being complete, which hampers reliable dating of
their evolution [1, 3–5, 8, 9].
The keen attention that micropaleontologists pay to
early planktonic foraminifers is explained by new finds
of these microorganisms at progressively older strati-
graphic levels. Moreover, study of this Protista group
helps us to understand several issues, such as evolution
of morphogenesis from early stages of taxa develop-
ment to their mature state; dependence of test morpho-
types on environmental parameters (including the water
temperature of the World Ocean in different periods of
geological history) closely correlated with paleocli-
matic evolution; and dispersal of these organisms and
widening of their domains from discrete occurrences
during their origination in the Early Mesozoic to global
expansion in the Late Jurassic and subsequent Creta-
ceous epoch. The find of planktonic foraminifers in the
Triassic provokes an additional problem related to one
of the greatest biotic crises at the Triassic–Jurassic
boundary when mass extinction affected planktonic
foraminifers and other groups of organisms that lost up
to 50% of their taxa. This crisis was slightly predated
by the most important event in foraminiferal evolution:
a new group of organisms with an absolutely different
skeleton, principally new mode of life, and tremendous
evolutionary potential that originated in the terminal
Triassic and rapidly occupied the entire World Ocean.
Therefore, the first find of a planktonic foraminifer
assemblage in reliably dated Triassic rocks of the
Crimea is of large significance. It should be noted that
we could observe morphological peculiarities of plank-
tonic foraminifers, because tests extracted from rocks
were studied.
Among the planktonic foraminifer assemblage of
six genera and eight species found in the Triassic rocks,
one genus and four species have been identified and
described for the first time. This assemblage is marked
by the presence of species with typical morphological
features of early stages of taxa development and char-
acteristic forms of mature evolutionary stages. Despite
the high diversity of morphotypes, morphological fea-
tures in some taxa are unstable. The existence of an
advanced assemblage of planktonic foraminifers,
which originated in pre-Rhaetian and Rhaetian times
and successfully survived the greatest biotic crisis,
specifies the crisis scenario and its impact on biota at
different levels of water column in the World Ocean.
The occurrence of forms with sinistral tests, which are
typical of cold-water conditions, among planktonic for-
aminifers implies a presumably cold hydrosphere, sim-
ilar to the present-day one, during the Triassic–Jurassic
biotic crisis.
We also studied the Upper Triassic limestone block
usually interpreted as an olistolith within the Lower
Jurassic Eskiorda Formation [2]. This terrigenous for-
mation has developed in the Lozovskaya zone of the
mountainous part of Crimea and contains numerous
bodies of different age (Carboniferous–Leiassic) lime-
stones. The Triassic block is one of the largest struc-
tures (100 m across). It is located northeast of the
Kichik-Saraman Plateau on the left bank of Izvestkovyi
Creek 2.5 km upstream of its inflow into the Partizan-
skoe water reservoir (Fig. 1a). Previous researchers
sampled Rhaetian brachiopods [6] and upper Norian–
Rhaetian foraminifers from different parts of this olis-
tolith [6, 7]. Since no bed-by-bed description of the
block was performed, positions of these fossils
remain unclear. Nevertheless, the normal block atti-
tude (NW 310
°
, dip angle 20
°
) allows its subdivision
into the following Late Triassic,
s.s.
Late Norian (Seva-
tian)–latest Rhaetian, lithostratigraphic units exposed
in the creek thalweg (from the bottom to top):
(1) Light gray, massive algal–brachiopodal lime-
stone. Apparent thickness 8 m.
(2) Pink, pelitomorphic, massive, biomicritic lime-
stone alternating with brachiopod coquina layers. Sam-
Find of Early Planktonic Foraminifers
in the Triassic of the Crimea
O. A. Korchagin, K. I. Kuznetsova, and N. Yu. Bragin
Presented by Academician M.A. Semikhatov December 9, 2002
Received December 10, 2002
Geological Institute, Russian Academy of Sciences,
Pyzhevskii per. 7, Moscow, 109017 Russia;
e-mail: bragin@geo.tv-sign.ru
GEOLOGY
DOKLADY EARTH SCIENCES
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No. 4
2003
FIND OF EARLY PLANKTONIC FORAMINIFERS IN THE TRIASSIC OF THE CRIMEA 483
ple 3 yielded foraminifers
Galeanella panticae
Zan-
ninetti and Bronnimann and conodonts
Neogondolellla
cf.
steinbergensis
(Mosher) of the Late Norian (Seava-
tian) age. Thickness 4 m.
(3) Light gray, massive, algal–brachiopodal lime-
stone. Thickness 4 m.
(4) Pink, crinoid, massive (obscure-bedded in the
upper part) limestone. Thickness 10 m.
(5) Pink, lumpy, obscure-bedded, biomicritic lime-
stone with brachiopods and microfossils. Samples 8–10
from this bed contain a diverse foraminiferal assem-
blage of Rhaetian age including benthic
Gaudryinella
kotlensis
Trifonova,
G. elegantissima
Kristan-Toll-
mann,
Gaudryina
sp.,
Ammobaculites
cf.
rhaeticus
Kristan-Tollmann,
Variostoma coniforme
Kristan-Toll-
mann,
Galeanella panticae
Zanninetti and Bronni-
mann,
Triasina
sp.,
Involutina
cf.
turgida
Kristan-Toll-
Fig. 1.
Position and structure of the Upper Triassic limestone block on the northern slope of the Kichik-Saraman Plateau (Crimean
Mountains). (a) Geological structure of the Alma and Bodrak interfluve [2]; (b) section of the Triassic limestone olistolith (obser-
vation point K-12); sampling levels (numbers on the left side of the column) and bed numbers (right side of the column) correspond
to those in the description. (
1)
Lower Cretaceous rocks; (
2)
Dzhidair Formation (Toarcian–Aalenian); (
3
) Eskiorda Formation
(Lower Jurassic); (
4
) Upper Tavriya Formation (Lower Jurassic); (
5
) Kurtsov and Salgir formations (Middle–Upper Triassic);
(
6
) steep faults; (
7
) low-angle overthrust; (
8
) stratigraphic boundaries; (
9
) Bodrak polygenic fault; (
10
) olistolith of Upper Triassic
limestones; (
11
) massive biohermal limestone; (
12
) micritic limestone; (
13
) organogenic-detrital crinoid–brachiopodal limestone;
(
14
) limy conglomerate; (
15
) sandstone and gritstone.
(a) (b)
Study area
Partizanskoe
water reservoir
1 km
K-12
10 m
11
10
9
8
7
6
5
4
3
2
1
Bed
6
Bed
5
Bed
4
Bed
3
Bed
2
Bed
1
K-12
123456
789101112
13 14 15
484
DOKLADY EARTH SCIENCES
Vol. 390
No. 4
2003
KORCHAGIN
et al.
mann,
Reophax rudis
Kristan-Tollmann,
Diplosphaer-
ella ramose
Kristan-Tollmann, and planktonic forms
Schmidita hedbergelloides
Fuchs,
Oberhauserella
quadrilobata
Fuchs,
O. prarhaetica
Fuchs,
Globulige-
rina almensis
O. Korchagin and K. Kuznetsova, sp. n.,
Sphaerogerina crimica
O. Korchagin and K. Kuzne-
tsova, gen. et sp. n.,
S. tuberculata
O. Korchagin and
K. Kuznetsova, gen. et sp. n.,
Praegubkinellla turge-
scens
Fuchs,
Wernliella explanata
O. Korchagin and K.
Kuznetsova sp. n. Thickness 3 m.
(6) Polymictic gritstone and coarse-grained sand-
stone with dispersed pebbles. The basal part is com-
posed of limy conglomerate. Apparent thickness 7 m.
The data suggest the following conclusions: (1) the
first appearance of true planktonic foraminifers is
related to the Triassic (Rhaetian) rocks (the oldest
stratigraphic level at the moment); (2) the planktonic
microbiota was characterized by a diverse composition
and unstable morphological features at the initial stages
of evolution; (3) based on peculiarities of test morpho-
types, habitat of this fauna corresponded to a cold
hydrosphere during evolutionary innovations; and (4)
the appearance of a new ecological type of fauna pre-
dated the mass extinction of biota (biotic crisis) at the
Triassic–Jurassic boundary (in our case).
Order GLOBIGERINIDA LANKASTER, 1885
Family GLOBIGERINIDAE LOEBLICH
AND TAPPAN, 1984
Genus
Globuligerina
Bignot and Guydader, 1971
Globuligerina almensis
O. Korchagin
and K. Kuznetsova, sp. n.
Fig. 2,
1–3
Etymology.
After find locality in the Alma River
basin, the Crimean Mountains.
Holotype.
No. 4776/10 stored at the Geological
Institute; the Crimea, northeastern slope of the Kichik-
Saraman Plateau, section K-12, Bed 5; Upper Triassic,
Rhaetian Stage.
Description.
Test is moderately trochospiral with
convex chambers loosely arranged in two whorls; cam-
bers of the early whorl are distinctly raised over those
in the last whorl; spiral side is evolute and strongly con-
vex; umbilical side is involute and slightly concave; the
last whorl consists of 3.0 to 3.5 almost uniform spheri-
cal chambers; chambers on umbilical side are flattened-
convex with near-umbilicus deeps; septal sutures on
spiral side are slightly depressed, straight radial in the
early whorl, and slightly curved in the last whorl;
sutures on umbilical side are depressed and straight;
umbilical area is of medium size and occupies one-third
of test diameter; test contour is strongly lobulate;
periphery is widely rounded; aperture is not observed;
and test surface after etching is even and smooth. Sinis-
tral tests are prevalent.
Dimensions (mm).
Holotype no. 4776/10:
D
= 0.2,
H
= 0.13.
Comparison.
The species differs from
Globulige-
rina oxfordiana
(Grigelis) in less convex chambers and
highly elevated early whorl of the test and from
Globu-
ligerina frequens
Fuchs in wider and open umbilicus
and strongly elevated early whorl of the test.
Distribution and age.
The Crimea, Rhaetian lime-
stones.
Material.
Five specimens of moderate preservation.
Genus
Sphaerogerina
O. Korchagin
and K. Kuznetsova, sp. n.
Etymology.
From Latin
sphaero
(spherical) indicat-
ing spherical shape of the test.
Type species.
Sphaerogerina tuberculata
O. Kor-
chagin and K. Kuznetsova, gen. and sp. n. The Crimea,
northeastern slope of the Kichik-Saraman Plateau, sec-
tion K-12, Bed 5; Upper Triassic, Rhaetian Stage.
Diagnosis.
Test spherical, compactly coiled, moder-
ately trochoidal, involute, consists of two whorls. The
last whorl includes 3–5 spherical inflated tightly
arranged chambers. Test contour is almost regular,
rounded, and slightly lobulate. Septal sutures are
straight, slightly depressed. Umbilicus is poorly
expressed, because internal margins of chambers are
tightly attached to each other and cover aperture. Aper-
ture is intraumbilical, basal, low- to high-arcuate, and
sometimes rimmed by narrow lip. Test surface after
etching is hummocky or coarsely rough. Wall is irregu-
larly porous.
Species composition.
Rhaetian rocks of the Crimea
enclose, in addition to type, species
Sphaerogerina
tuberculata
,
S. crimica
O. Korchagin and K. Kuznets-
ova gen. and sp. n.
Comparison.
The new genus differs from
Compac-
togerina
Simmons
et al.
, 1997 in lower number of
chambers in the last whorl, absence of widely arcuate
aperture characteristic of
Compactogerina
genus, and
irregularly porous and hummocky test surface. It differs
from
Favusella
genus in hummocky, rather than reticu-
lar, test surface.
Distribution and age.
The Crimea, Upper Triassic,
Rhaetian Stage.
Sphaerogerina tuberculata
O. Korchagin
and K. Kuznetsova, gen. and sp. n.
Fig. 2,
7–9
Etymology.
From Latin
tuberculatus
(hummocky).
Holotype.
No. 4776/14 stored at Geological Insti-
tute; the Crimea, northeastern slope of the Kichik-Sara-
man Plateau, section K-12, Bed 5; Upper Triassic, Rha-
etian Stage.
Description.
Test is moderately trochospiral,
spherical, with 2.5 spiral whorls; the last whorl con-
sists of 3–4 spherical, closely arranged chambers grad-
ually increasing in size; septal sutures are straight,
radial, slightly depressed or flat on spiral side and flat
DOKLADY EARTH SCIENCES
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No. 4
2003
FIND OF EARLY PLANKTONIC FORAMINIFERS IN THE TRIASSIC OF THE CRIMEA 485
on umbilical side; chambers on umbilical side are very
tightly attached to each other; therefore, umbilicus is
poorly expressed; periphery is widely rounded; test
contour is oval, rounded, or slightly lobulate; aperture
is intermarginal, basal, rounded, arcuate, sometimes
rimmed by lip; test surface after etching in acids is
rough and hummocky.
Dimensions (mm).
Holotype no. 4776/14:
D
= 0.28,
d
= 0.21,
H
= 0.27.
Distribution and age.
New species occurs in Rha-
etian rocks of the Crimea.
Material.
Approximately 15 specimens of moderate
preservation.
Sphaerogerina crimica
O. Korchagin
and K. Kuznetsova, gen. and sp. n.
Fig. 2,
10–11
Etymology.
After locality of find (the Crimea).
123
456
78 9
10 11
Fig. 2. Planktonic foraminifers from Rhaetian rocks of the Crimea. All specimens are taken from the Upper Triassic (Rhaetian
Stage) section K-12 (Bed 5) exposed on the northeastern slope of the Kichik-Saraman Plateau and are stored at the Geological Insti-
tute under corresponding numbers. Globuligerina almensis O. Korchagin and K. Kuznetsova, sp. n.: (1) holotype no. 4776/10, side
view, sinistral test, ×220, (2) paratype no. 4776/11, umbilical view, ×220, (3) paratype, no 4776/12, peripheral view, ×220; Wern-
liella explanata O. Korchagin and K. Kuznetsova, sp. n.: (4) holotype no. 4776/1, spiral side, dextral test, ×170, (5) paratype
no. 4776/2, umbilical view, sinistral test, ×210, (6) paratype no. 4776/3, peripheral view, ×125; Sphaerogerina tuberculata O. Kor-
chagin and K. Kuznetsova, gen. and sp. n.: (7) holotype no. 4776/14, spiral side, dextral test, ×144, (8) paratype no. 4776/15, side
view, ×144, (9) paratype no. 4776/16, umbilical view, ×144; Spherogerina crimica O. Korchagin and K. Kuznetsova, gen. and sp. n.:
(10) holotype no. 4776/18, side view, dextral test, ×140, (11) paratype no. 4776/19, umbilical view, ×160.
486
DOKLADY EARTH SCIENCES Vol. 390 No. 4 2003
KORCHAGIN et al.
Holotype. No. 4776/18 stored at Geological Insti-
tute; the Crimea, northeastern slope of the Kichik-Sara-
man Plateau, section K-12, Bed 5; Upper Triassic, Rha-
etian Stage.
Description. Test is spherical, with slightly elevated
cone-shaped chambers in early whorl, tightly coiled,
moderately trochoid, consisting of two spiral whorls;
last whorl includes three spherical inflated chambers;
septal sutures are radial, flat or slightly depressed on
spiral side and straight, radial, flat or slightly depressed
on umbilical side; chambers on umbilical side of last
whorl are very tightly arranged so that umbilicus is
missing; periphery is widely rounded; test contour is
rounded, even, or slightly lobulate; aperture is unob-
servable; test surface after etching by acids is even,
smooth, or slightly rough.
Dimensions (mm). Holotype no. 4776/18: D = 0.18,
H = 0.19.
Distribution and age. Species occurs in Rhaetian
rocks of the Crimea.
Material. Six specimens of moderate preservation.
Family OBERHAUSERELLIDAE FUCHS, 1970
Genus Wernliella K. Kuznetsova, sp. n.
Wernliella explanata O. Korchagin
and K. Kuznetsova, sp. n.
Fig. 2, 4–6
Etymology. From Latin explanatus (flattened).
Holotype. No. 4776/1 stored at the Geological Insti-
tute; the Crimea, northeastern slope of the Kichik-Sara-
man Plateau, section K-12, Bed 5; Upper Triassic, Rha-
etian Stage.
Description. Test is small, low- to medium-trochospi-
ral, patelliform, with slightly convex spiral and slightly
concave umbilical sides; test consists of 2.0–2.5 whorls;
last whorl comprises 4–4.5 chambers; chambers of initial
whorl are slightly elevated above last whorl; test contour
is oval-quadrangular and slightly lobulate; chambers on
spiral side are crescent-shaped or trapezoid, flattened-
convex, gradually increasing in size; septal sutures are
oblique and depressed; chambers are flattened-convex
on umbilical side; last chamber is shifted to the umbilical
side and partly overlaps umbilicus occupying sometimes
one-third of test diameter; septal sutures are straight,
radial, and depressed; umbilicus is small, shallow, and
partly closed by the lower termination of the last cham-
ber; periphery is slightly tapered and rounded; aperture is
umbilical (slitlike or low-arcuate exrtaumbilical), partly
covered by triangular plate or flap; test surface is spiny or
hummocky on spiral side and smoother on umbilical
side; wall is fine-grained. Dextral tests are prevalent .
Dimensions (mm). Holotype no. 4776/1: D = 0.25,
H = 0.14.
Comparison. The species differs from Wernliella
toracensis K. Kuznetsova in more lobulate test outlines
and looser arrangement of chambers in last whorl.
Distribution and age. Species occurs in Rhaetian
rocks of the Crimea.
Material. Twenty specimens of moderate preserva-
tion.
ACKNOWLEDGMENTS
This work was supported by the Russian Founda-
tion for Basic Research, project nos. 00-05-64298,
00-05-64618, and 02-05-64335.
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... Norian-Rhaetian foraminifers were further listed from the limestoneclay unit of the Severo-Nekrasovskaya, Chernigovskaya and Molodezhninskaya wells in the Western Precaucasus (Vuks, 2007). Late Norian and/or Rhaetian foraminifers are also known from exotic blocks embedded in an olistostrome complex in Crimea (Kotlyar et al., 1999;Vuks, 2000;Korchagin et al., 2003). Foraminifers mentioned in these works are listed in Table 1. ...
... The Nayband Formation deposited in a range of environments from outer ramp to marginal marine and deltaic settings Table 1 Foraminifers previously mentioned from the Caucasus Fore Range and adjacent areas. Illustrations are given in Efimova (1975), Pronina and Vuks (1996), and Korchagin et al. (2003). Efimova (1975), Vuks ( , 2000Vuks ( , 2004 Western Pronina and Vuks (1996), Kotlyar et al. (1999), Vuks (2000), Korchagin et al. (2003) (Fürsich et al., 2005). ...
... Illustrations are given in Efimova (1975), Pronina and Vuks (1996), and Korchagin et al. (2003). Efimova (1975), Vuks ( , 2000Vuks ( , 2004 Western Pronina and Vuks (1996), Kotlyar et al. (1999), Vuks (2000), Korchagin et al. (2003) (Fürsich et al., 2005). Foraminifers are not particularly abundant in the Nayband Formation and are currently known only from the Bidestan and the Howz-e-Khan Members (Brönnimann et al., 1971;Zaninetti and Brönnimann, 1974;Senowbari-Daryan et al., 2008. ...
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... Conoglobigerina Morozova, 1961, in Morozova andMoskalenko (1961); Tenuigerina Gorbachik & Kuznetsova, 1998. Korchagin & Kuznetsova, 2003) (Family Sphaerogerinidae BouDagher-Fadel, 2012. ...
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Planktic foraminifera have traditionally been classified within a single order: Globigerinida. However, recent phylogenetic studies, both molecular and stratophenetic, are evidencing the polyphyletic origin of planktic foraminifera from several benthic ancestors. At least four independent events of benthic-planktic transition have been identified. One of them occurred after the Cretaceous–Paleogene boundary mass extinction, originating the first Cenozoic globigerinids. Another three occurred in the Mesozoic, originating three groups of planktic foraminifera (globotruncanids, heterohelicids and guembelitriids) not related phylogenetically to each other or to current globigerinids. These findings make it necessary to carry out an exhaustive review of their suprageneric systematics, mainly at the order level. Here we propose a new, more natural classification, grouping them into four orders: Globigerinida, Heterohelicida, Globotruncanida n. ord., and Guembelitriida n. ord. To better reflect the diversity and phylogeny of planktic foraminifera, we have also defined two new superfamilies: Abathomphaloidea n. superfam. and Parvularugoglobigerinoidea n. superfam., and one new family: Parvularuglobigerinidae n. fam.
... In this study, we ignore Globigerina gaurdakensis Balakhmatova and Morozova (1961), Globigerina spuriensis Bars and Ohm 1968 and Globuligerina geczyi Görög 1994, as being benthonics or non-Jurassic taxa (see Stam 1986 and plate 2.10 in Simmons et al. 1997). We 'reject' all pre-Cretaceous taxa described as glauconitic casts (like Globigerina conica, G. terquemi and others without wall structure and often without clear aperture features), or pseudo-planktonic morphotypes from the Triassic and Jurassic of Austria (Fuchs 1975) and Crimea (Korchagin et al. 2002). Good documentation on problems with glauconitic cast typology or pseudo-planktonics is in Stam (1986, Chapter 5) and Simmons et al. (1997). ...
... Such (pseudo-) types without original wall structure and often without clear apertural features cannot be used to describe and identify planktonic foraminifera. In the same vein, the pseudo-planktonic morphotypes from the Triassic and Jurassic of Austria (Fuchs 1975) and Crimea (Korchagin et al. 2002) are rejected. Good documentation on glauconitic cast types or pseudo-planktonics is in Stam (Stam 1986, Chapter 5) and Simmons et al. (1997). ...
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The taxonomy is modernized and updated for Jurassic planktonic foraminifera using all available literature and stratigraphic series of sediment samples from Canada, Portugal, France, Switzerland, Poland, Lithuania, Russia and Dagestan. The regional stratigraphy of all sampled sections is outlined. Many of the 65–200 µm sample residues yielded well-preserved free specimens, with local assemblages containing up to six species. Thin sections were studied also but do not allow detailed taxonomy. Two genera are described: Globuligerina and Conoglobigerina. Globuligerina probably appeared in the late Toarcian (late Early Jurassic) and Conoglobigerina first occurred in middle Oxfordian (early Late Jurassic). A principal difference between Globuligerina and Conoglobigerina is that the former has a smooth to pustulose wall surface texture and the latter a reticulate wall surface texture. Within the two genera, ten species are described, including from older to younger: Globuligerina dagestanica (Morozova), G. avariformis (Kasimova), G. balakhmatovae (Morozova), G. oxfordiana (Grigelis), G. bathoniana (Pazdrowa), G. jurassica (Hofman), G. oxfordiana (Grigelis) calloviensis Kuznetsova emended, G. tojeiraensis Gradstein, Conoglobigerina helvetojurassica (Haeusler), C. grigelisi Gradstein and C. gulekhensis (Gorbachik and Poroshina). The coarsely perforate ‘Globuligerina’ stellapolaris needs more investigation to establish its identity as a Jurassic or a Late Cenozoic taxon (Gradstein 2017a). Globuligerina balakhmatovae, G. oxfordiana and G. bathoniana occur from Bajocian through early Kimmeridgian, or even Tithonian. Subtle morphological trends may refine stratigraphic usage. Other taxa have shorter stratigraphic ranges. Nineteen plates and ten type species figures detail morphology of all taxa. For key taxa, both the types and specimens from other localities are illustrated.
... It is of high relevance for palaeotectonic and palaeogeographic interpretations to highlight the close lithological and palaeobiological affi nities of the allochthonous Rhaetian limestone drilled on the Romanian Black Sea shelf with the Rhaetian brachiopod-bearing biomicritic limestone within the Kichik-Sarman olistolith embedded in the Lower Eski-Orda Formation, located on the Alma-Bodrak interfl uve, east of Bakhchisaray, in the Mountainous Crimea (Korchagin et al. 2003), and also within other Crimean exotic limestone blocks (Kotlyar et al. 1999). The brachiopod fauna of the allochthonous Rhaetian limestone in drill core CM31 contains similar species to that of the allochthonous Rhaetian limestone in the Mountainous Crimea as recorded by Dagys (1974). ...
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We describe the first known Rhaetian assemblages from a drill core on the Romanian Black Sea shelf. They developed on an outer shelf with relatively normal marine oxygenation and demonstrate that Pokornyopsis, forerunner of modern troglobitic taxa, may not have been troglobitic in the Triassic. The internal structure of Bairdiidae carapaces has been observed by X-ray micro-computed tomography scanning (CT-scan) and previously inaccessible characters now allow for the clarification of the taxonomy of this family. (PDF) Rhaetian (Late Triassic) ostracods (Crustacea, Ostracoda) from the offshore prolongation of the North Dobrogean Orogen into the Romanian Black Sea shelf. Available from: https://www.researchgate.net/publication/348350130_Rhaetian_Late_Triassic_ostracods_Crustacea_Ostracoda_from_the_offshore_prolongation_of_the_North_Dobrogean_Orogen_into_the_Romanian_Black_Sea_shelf [accessed Jan 13 2021].
... It is of high relevance for palaeotectonic and palaeogeographic interpretations to highlight the close lithological and palaeobiological affinities of the allochthonous Rhaetian limestone drilled on the Romanian Black Sea shelf with the Rhaetian brachiopod-bearing biomicritic limestone within the Kichik-Sarman olistolith embedded in the Lower Eski-Orda Formation, located on the Alma-Bodrak interfluve, east of Bakhchisaray, in the Mountainous Crimea (Korchagin et al. 2003), and also within other Crimean exotic limestone blocks (Kotlyar et al. 1999). The brachiopod fauna of the allochthonous Rhaetian limestone in drill core CM31 contains similar species to that of the allochthonous Rhaetian limestone in the Mountainous Crimea as recorded by Dagys (1974). ...
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The present study evaluates the significance of Triassic ostracods from the Romanian Black Sea shelf as part of a project for the understanding of palaeoceanographical evolution of the offshore extension of the North Dobrogean Orogen. The drill core CM31, sampled from the borehole 817 Lebăda Vest drilled on the western Romanian portion of Black Sea shelf, contains sediments of Rhaetian, Late Triassic age. The taxonomy of ostracods obtained is discussed and adds to the scientific understanding of marine ostracods during the Rhaetian stage. We document 72 species, of which seven are new: Histriabairdia pontuseuxinusensis gen. nov. et sp. nov., Bairdiacypris argonautaii sp. nov., Ceratobairdia? akhilleusi sp. nov., Isobythocypris atalantella sp. nov., Petasobairdia amazonella sp. nov., Paracypris ovidi sp. nov., Pseudo-macrocypris? kerabani sp. nov. Histriabairdia gen. nov. is introduced to accommodate species of the Triassic-Jurassic interval previously attributed to the modern genus Anchistrocheles. These assemblages point to an outer shelf environmental with relatively normal marine oxygenation. The oldest occurrence of Pokornyopsis indicates that this forerunner of modern troglobitic ostracods may not have been troglobitic in the Triassic.
... 2002-Using acid extraction, Korchagin et al. (2002) described a small foraminiferal assemblage, mostly without wall structure and wall texture features from Upper Triassic strata in the Crimea, Russia, with new taxa of Globuligerina, Sphaerogerina and Wernliella. The new taxa are declared to be planktonics. ...
Article
Over 70 publications on Jurassic planktonic foraminifera, particularly by East and West European and Canadian micropalaeontologists, are summarized and briefly annotated. It provides an annotated historic overview for this poorly understood group of microfossils, going back to 1881 when Haeusler described Globigerina helvetojurassica from the Birmenstorfer Schichten of Oxfordian age in Canton Aargau, Switzerland.
... However , their systematic and taxonomy is not yet arranged in an acceptable form. In addition, it has been reported about some finds of planktonic foraminifera in the Upper Rhaetian of uppermost Triassic of the Crimea (Korchagin et al., 2003), which should be studied on a more representative sampling material. Actually, the increasing knowledge sets up more general queries, first at all, as regards the origin and early evolution, biodiversity and biogeography of Jurassic planktonic foraminifera (e. g., Grigelis, 1983; Gorbatchik et al., 1986; Boudagher-Fadel et al., 1997; Kuznetsova, 2000; Hart et al., 2002 Hart et al., , 2003 Görög, Wernli, 2003; Hudson et al., 2009; etc.). ...
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The article presents the self-revision and re-description of the first planktonic foraminifera Globuligerina oxfordiana (Grigelis, 1958) discovered in the Upper Jurassic of Lithuania. The original article published in 1958 in a Russian periodical (Moscow) is translated, supplied by additional comments, and illustrated by SEM laser electronic micrographs.
... (1) some blocks of volcanic rocks (presumably of Bajocian-Bathonian or Callovian age) were found in shales of a very dark colour (TG) in Lozovoye quarry (Zaika-Novackij 1981;Zaika-Novackij & Solov'ev 1988;Spiridonov et al. 1990a, b); (2) in some places, the TG contains blocks of limestones of latest Triassic (Korchagin et al. 2003) and Early Jurassic (Kazantcev et al. 1989;Ippolitov et al. 2008) age; (3) Triassic fauna selected from flysch are suggested to have been reworked (Spiridonov et al. 1990a, b;Popadyuk et al. 2013a); (4) ammonites of Early Cretaceous age (Barremian -Aptian) were found in a limestone block inside the TG near Simferopol (Dehtyareva et al. 1978;Popadyuk & Smirnov 1991); (5) Cenomanian foraminifers (Guembelina cenomanica Agal.) were found in the TG from depths of 94 -200 m (Mender well) via drilling close to Prohladnoye and Bahchisaray (western Crimea) (Yanin 1976;Popadyuk et al. 2013a); and (6) foraminifer assemblages of Albian age have been identified (Popadyuk et al. 2013a, b) in the siliciclastic sediments assumed to belong to the TG (Late Triassic -Early Jurassic age frame). The age of deformation is also in doubt. ...
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Abstract: The tectonic evolution of the Eastern Black Sea Basin has previously been explained based on offshore and onshore data, some of the latter from the Crimean Mountains (CM). However, changes in the stratigraphy of the CM have recently been proposed: the Late Triassic–Early Jurassic Tauric Group was assigned as younger (Albian). To clarify the stratigraphy and the tectonic evolution of this area, we sampled the eastern CM for micropalaeontological datings (nannoplankton). The results demonstrate an Early Cretaceous age for the Tauric Group in the eastern CM. The samples contained substantial amounts of volcanic ash, indicating a period of magmatic activity along all the eastern CM. Our field observations allowed us to propose a new structural map and cross-sections, using which three main tectonic units were distinguished. We define a phase of extension during the Early Cretaceous and one of shortening during the Paleocene–Early Eocene, before the main Middle Eocene limestone unconformity. These two phases are related to: (1) the opening of the Eastern Black Sea Basin along NNW–SSE-trending normal faults and the associated magmatism; and (2) north–south shortening that could be comparable with the inversion in Dobrogea and/or with north–south shortening linked to the collision of continental blocks in the Pontides and Taurides domains.
Chapter
Only a few Cretaceous species survived the K–P mass extinction, but of these just three forms, namely, Hedbergella monmouthensis, H. holmdelensis, and Guembelitria cretacea gave rise to the entire subsequent Paleogene stock. Despite this simple beginning, there is some divergence in the taxonomic and phylogenetic classification of the resulting Paleogene forms. These anomalies are resolved in this chapter by a revised taxonomy, in which three new superfamilies, three new families, and three new genera are introduced. We propose that the Paleogene planktonic foraminifera should be divided into seven superfamilies, which flourished at different stages and included 16 families. Thus, the Globigerinitoidea include the globanomalinids, which first evolved from Hedbergella holmedelensis in the Danian; the keeled planorotalids, which evolved from the globanomalinids in the Selandian; the tenuitellids, which evolved from the globanomalinids in the Late Bartonian; and the globigerinitids, which evolved from the tenuitellids in the Late Priabonian. The Hantkeninoidea evolved from the globanomalinids in the Late Ypresian. The newly defined Eoglobigerinoidea consist of the high trochospiral eoglobigerinids, which evolved from Hedbergella monmouthensis in the Danian. The Globigerinoidea evolved from the eoglobigerinids in the Early Eocene and contain the globigerinids, which evolved in the Ypresian; the globorotaliids, which evolved from the globigerinids in the Late Bartonian; the porticulasphaerids that evolved from the globigerinids in the Late Lutetian; and the turborotalitids that also evolved from the globigerinids in the Lutetian. The newly defined Truncorotaloidinoidea also evolved from H. monmouthensis in the Danian. The newly defined but short-lived triserial Globoconusoidea evolved from the guembelitriids in the Danian, while other bi- and triserial forms are placed in the superfamily Heterohelicoidea and include the triserial guembelitriids, which died out at the top of the Oligocene (but similar forms reappear in the Late Pliocene); the biserial chiloguembelinids, which evolved from the guembelitriids in the Danian; the enrolled, biserial cassigerinellids, which evolved from the chiloguembelinids in the Early Lutetian; and the heterohelicids, which survived the Cretaceous–Paleocene extinction event. Overall, species diversity increased gradually from the Paleocene into the Middle Eocene (Lutetian) during a time of globally warm conditions, but with cooling from the Bartonian to the Chattian in the Late Oligocene, there was a notable decrease in species diversity. Throughout the Paleogene, extinction rates remained fairly constant; however, extinction events were more notable at the family level. The eoglobigerinids dwindled gradually until they disappeared at the end of the Oligocene, which also saw the final extinction of the Guembelitriidae. This stratigraphic boundary, however, is not marked by any major discontinuity, and the planktonic foraminifera of the Neogene show a gradual, continuous development from those forms of the seven families of Paleogene planktonic foraminifera that survived uninterrupted into the Miocene.
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On the base of French-Ukrainian collaboration (DARIUS program), in the eastern part of the Crimea Mountain the first stage of field work was performed, during which the samples of flysch rocks were taken for micropaleontological analysis (Nanofossilsdating). It made possible to plot the first variant of structural geological map of this area and refresh the age of flysh products on it up to Early Cretaceous. The results obtained allow us to revise tectonic evolution of the East Crimea casting away the Cimmerian orogenesis.
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Exotic limestone blocks of Permian and Triassic age occur in the Middle Triassic-Middle Jurassic Crimean olistostrome complex of the Marta and Alma River basins and in the Simferopol area. Rich assemblages of small foraminifers, fusulinids, brachiopods, rare ammonoids, and sphinctozoans occur in these blocks. Fossils from Permian blocks indicate the presence of zonal assemblages for the Bolorian, Kubergandian, Murgabian, Midian, Dzhulfian, and Dorashamian stages. The Neoschwagerina simplex fusulinid zone is extended upward based on the presence in our material of Kubergandian ammonoids with Neoschwagerina simplex Ozawa. Comparison of the fauna from Triassic blocks to assemblages from other regions of the Tethys indicates that the age is Late Triassic Rhaetian corresponding to the Vandaites sturzenbaumi ammonoid zone.
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