GeolCarp_Vol51_No6_399

GEOLOGICA CARPATHICA, 51, 6, BRATISLAVA, DECEMBER 2000

399406

NANNOPLANKTON OF THE TARKHANIAN DEPOSITS

OF THE KERCH PENINSULA (CRIMEA)

AIDA S. ANDREYEVA-GRIGOROVICH

and NATALIA A. SAVYTSKAYA

Department of Geology and Paleontology, Faculty of Science, Comenius University, Mlynská dolina, 842 15 Bratislava, Slovak Republic

Ukrainian State Geological-Research Institute, 57001 Lviv, Ukraine

(Manuscript received May 18, 2000; accepted in revised form October 17, 2000)

Abstract: Tarkhanian calcareous nannoplankton in the area of Crimea have been studied in the sequence of Tarkhan

s.str., new stratotype locality Maly Kamyshlak, Skelia section and in the Sokol-60 well (350.0390.0 m). Associations

of nannofossils are assigned to the zone NN5 and can be correlated with the calcareous nannoplankton associations of

the Lower Badenian deposits of the Central Paratethys and the Langhian sediments of the Mediterranean area.

Paleoreconstructions based on nannofossils have shown that at the beginning of the Tarkhanian transgression a warm

sedimentary area with normal salinity was formed. It was connected with the basins of Western Paratethys and there

is a possibility of connections with the Indian Ocean or Mediterranean Sea. Quantitative, as well as qualitative impov-

erishment of nannoplankton points to change of the basin regime, connected with strong terrigenous input, partial

isolation and salinity decrease (the time of accumulation of Spirialis clays upper part).

Key words: Miocene, Tarkhanian, Kerch Peninsula, nannoplankton.

Introduction

Tarkhanian deposits were first recognized in the Kerch Penin-

sula by N.I. Andrusov in 1887 as a thin horizon with Pseudoa-

mussium denudatum (Reuss), Nucula placentina Lamk., Os-

trea cochlear (Poli) and others. Later on some investigators

(Zhyzhchenko 1940; Merklin et al. 1964) enlarged the volume

of Tarkhanian horizon, by assigning the overlying succession

of Spirialis clays. As a result of revision of the Neogene re-

gional stages of the Eastern Paratethys, the Tarkhanian se-

quence has got a status of a regional stage of Eastern Parat-

ethys (Nevesskaya et al. 1975) taking into consideration its

widespread occurrence in the Euxinic-Caspian area.

In spite of the long history of studying the Tarkhanian de-

posits and rich paleontological material on different groups of

fossils: mollusks (Davitashvili 1933; Barg et al. 1975; Ana-

niashvili 1985), foraminifers (Bogdanovich 1965; Pishvanova

1978), nannoplankton (Andreyeva-Grigorovich in: Nosovsky

et al. 1976; Minashvili 1981, 1992; Nosovsky & Bogdanovich

1984; Muzylov & Golovina 1987) the problem of the age and

stratigraphical correlation of the Tarkhanian succession is still

topical.

In the 70-s the new stratotype of the regional Tarkhanian

Stage was proposed as a result of prospecting in the Kerch

Peninsula. The new stratotype (neostratotype) in the Maly Ka-

myshlak is on the Sea of Azov coast. The Kamyshlak Beds

(lower part), the beds with A. denudatum (middle part) = the

Tarkhan and Yurakov Beds = Spirialis beds (upper part) are in-

cluded in the neostratotype (Nosovsky et al. 1976).

Studied material

The paper contains a study of new material from the Skelia

section and revision of the old materials (Andreyeva-Grigor-

ovich in Nosovsky et al. 1976). The samples were studied

from the stratotype of Tarkhan near Tarkhan Cape (materials

by Barg), new stratotype section of Maly Kamyshlak (35 sam-

ples), section of Skelia (26 samples) and 20 samples from

Sokol-60 well (material by Nosovsky) (Fig. 1).

All the samples were prepared with the standard smear slide

technique for light microscope observations (LM). The inves-

tigations were carried out under LM at a magnification of

1200

using phase contrast and crossed nicols. Several speci-

mens photographed under SEM (6000

, 7000

) and LM were

illustrated in Pls. I, II.

Fig. 1. Location map of the studied Tarkhanian sequences.

A z o v S e a

Kazantyp Cape

Tarkhan Cape

Yurakov

Kut

Kerch

Feodosia

B l a c k S e a

Tschokrak

Lake

Sokol 60

Stratotype locality of Tarkhanian

Skelia

Maly Kamyslak, new stratotype

Well

Towns, villages

1:1,000,000

400 ANDREYEVA-GRIGOROVICH and SAVYTSKAYA

Nannoflora from the Tarkhanian sequence

Tarkhan s.str. The sequence situated on the western slope

of the Tarkhan Cape on the Azov coast, was proposed by An-

drusov in 1884 (Andrusov 1887) as the stratotype locality of

the Tarkhanian Stage. Paleontological character of the de-

posits was based on the mollusks fauna (Zhyzhchenko 1940;

Davitashvili 1933) only. Samples for the nannoplankton study

were given by I.M. Barg. Depiction of the stratotype follows

from the bottom to the top.

1. Clays, dark-grey, non-carbonate with faded jarosite.

Thickness 1.20 m. Nannoplankton is not found (Maikop Fm.).

2. Clays, dark-grey to black, non-carbonate, shaly. Thick-

ness 1.50 m. Nannoplankton is not found (Maikop Fm.).

3. Clays, grey carbonate. Thickness 0.05 m. Rare species

are found: Coccolithus pelagicus, Helicosphaera cf. carteri,

Braarudosphaera bigelowii, Sphenolithus heteromorphus,

Rhabdosphaera sicca (Kamyshlak Beds).

4. Tarkhan Beds marls dark-grey, dense with A. denuda-

tum. Thickness 0.2 m. They contain: Coccolithus pelagicus

(acme), Helicosphaera carteri, H. waltrans, Braaru-

dosphaera bigelowii, Sphenolithus heteromorphus (acme), S.

cf. abies, Rhabdosphaera sicca (acme), Pontosphaera disco-

pora, Cyclicargolithus floridanus.

5. Clays grey, limy with pteropod remnants. Thickness 6.0

m. In the lower part of the succession they contain (1 m): Coc-

colithus pelagicus, Helicosphaera carteri, H. sp., Discoaster

variabilis, Sphenolithus heteromorphus (acme), S. abies,

Rhabdosphaera sicca, Braarudosphaera bigelowii, Ponto-

sphaera discopora. In the upper part of the succession they

contain impoverished complex with Coccolithus pelagicus,

Helicosphaera carteri, Cyclicargolithus leptoporus, Spheno-

lithus cf. abies, Sphenolithus heteromorphus, Perforocalcinel-

la fusiformis. Sometimes rare re-deposited species of Paleo-

gene algoflora are present (Lower part of the Yurakov Beds).

Associations from the marl beds with A. denudatum and

from the Yurakov Beds are most abundant in species and

quantitative respects. These complexes are contemporaneous

and correspond to NN5

Sphenolithus heteromorphus Zone

(Martini 1971), based on species likeness.

Maly Kamyshlak the new stratotype of the

Tarkhanian Stage. The section is situated along southern

Azov coast, 3 km west of the village of Yurkino.

Depiction of the neostratotype follows, from the bottom to

the top:

About the Maikopian (Korolov Beds) non-carbonate clays

pass into the (Fig. 2):

1. Kamyshlak Beds (thickness 3.5 m) dark-grey lightly

carbonate and non-carbonate vague bedded clays with a sprin-

kle of jarosite. The following nannoplankton forms are

present here: Braarudosphaera bigelowii, Coccolithus pelagi-

cus, Rhabdosphaera sicca, Helicosphaera carteri, Spheno-

lithus heteromorphus, Coronocyclus nitescens, Sphenolithus

moriformis.

2. Tarkhan Beds with Amussium denudatum (thickness 0.2

m) dark-grey marls, dense, overfilled with thin walled

shells of mollusks. The association of nannoplankton is repre-

Fig. 2. Distribution of nannoplankton in the Maly Kamyshlak sequence.

NANNOPLANKTON OF THE TARKHANIAN DEPOSITS 401

Plate I: Fig. 1. Helicosphaera granulata (Bukry & Percival); crossed nicols, Tarkhan sequence. Figs. 2, 3. Helicosphaera carteri (Wallich),

crossed nicols; 2 Sample S3, Skelia sequence; 3 Sample MK5, Maly Kamyshlak sequence. Fig. 4. Helicosphaera cf. waltrans Theodo-

ridis, crossed nicols; Sample S7, Skelia sequence. Figs. 58. Sphenolithus heteromorphus Deflandre; crossed nicols; 5 Sample MK5, 6

Sample MK14, 7 Tarkhan sequence, 8 Sample MK31, Maly Kamyshlak sequence. Fig. 9. Sphenolithus cf. abies Deflandre; crossed

nicols; Sample MK26 Maly Kamyshlak sequence. Fig. 10. Calcidiscus premacintyrei Theodoridis, crossed nicols; Sample S26, Skelia se-

quence. Figs. 11, 12. Reticulofenestra pseudoumbilicus (Gartner); crossed nicols; 11 Sample S5 Skelia sequence, 12 Sample MK22,

Maly Kamyshlak sequence. Figs. 13, 14. Rhabdosphaera sicca Stradner; 13 crossed nicols, 14 Sample S3, Skelia sequence. Fig. 15.

Braarudosphaera bigelowii subsp. parvula Stradner, Sample S26 Skelia sequence. Fig. 16. Braarudosphaera bigelowii (Gran & Braarud),

crossed nicols, Tarkhan sequence. Fig. 17. Cyclicargolithus floridanus (Roth & Hay), Sample S3, Skelia sequence. Figs. 18, 19, 20. Perfo-

calcinella fusiformis Bona; crossed nicols, Sample S26 Skelia sequence.

sented by the next species: Coccolithus pelagicus, Heli-

cosphaera carteri, H. cf. mediterranea, H. waltrans, H. gran-

ulata, Cyclicargolithus floridanus, Calcidiscus leptoporus, C.

premacintyrei, Sphenolithus heteromorphus, S. cf. abies, S.

moriformis, Reticulofenestra pseudoumbilicus, Rhab-

dosphaera sicca, Braarudosphaera bigelowii, Thora-

cosphaera saxea, Coronocyclus nitescens. Re-deposited spe-

cies of the Upper Cretaceous and Paleogene are present.

3. Yurakov Beds (thickness to 90 m) grey clays, calcare-

ous or subcarbonate, arenaceous with the relics of the shells of

NANNOPLANKTON OF THE TARKHANIAN DEPOSITS 403

The Skelia section is situated on the Azov coast two km

west of Yurkino village. The next sequence of the beds is

shown from the bottom to the top (Fig. 3):

1. Kamyshlak Beds (thickness 5.0 m). Nannoplankton is not

found there.

2. Tarkhan Beds with Amussium denudatum (thickness 0.15

m) shelly limestones, and thin-laminated grey marly clays

(0.3 m). Association of nannoplankton is represented by: Coc-

colithus pelagicus, Cyclicargolithus floridanus, Heli-

cosphaera carteri, H. waltrans, H. cf. walbersdorfensis, Sphe-

nolithus heteromorphus, S. moriformis, S. compactus,

Calcidiscus leptoporus, C. premacintyrei, Rhabdosphaera sic-

ca, Thoracosphaera heimii.

Representatives of the genera Coccolithus, Helicosphaera

and Sphenolithus heteromorphus prevail in the above men-

tioned complex.

3. Yurakov Beds (thickness is approximately 90 m.)

dark-grey clays, carbonate or non-carbonate, foliated, fre-

quently sandy, with sprinkles of jarosite. Surfaces of the beds

are often completely covered by Spiratella (Limacina). Some

intercalations among the clays contain siderite concretions.

The intercalation (1.5 m) of greenish-grey bedded marls with

lenses of ferritic clays are present at the top of the succession.

In the carbonate intercalations just above the marls with Amus-

sium denudatum (~ 1.5 m) the next complex of nannoplankton

was found: Coccolithus pelagicus, Cyclicargolithus florida-

nus, Sphenolithus abies, S. heteromorphus, S. moriformis,

Reticulofenestra pseudoumbilicus, Helicosphaera carteri,

Braarudosphaera bigelowii, Pontosphaera multipora, Thora-

cosphaera heimii, Triquetrorhabdulus rugosus.

Fig. 3. Distribution of nannoplankton in the Skelia sequence.

A poor association of nannoplankton has been found at the

top of the succession, with rare Coccolithus pelagicus, Retic-

ulofenestra pseudoumbilicus, Sphenolithus abies, Braaru-

dosphaera bigelowii subsp. parvula, Perforocalcinella fusi-

formis.

4. Detritic limestones of the Tschokrakian Stage lies with

the sharp hiatus on the Yurakov Beds (Spirialis clays). Nanno-

plankton is absent there.

Sokol-60 Borehole

Apart from natural sections in the north-eastern part of

Kerch Peninsula borehole-core material from the central part

from the peninsula (south-west of Tschokrak lake) was inves-

tigated. Sokol-60 well is situated 2 km north of Sokol village.

The following sequence of beds is shown from the top to the

bottom.

1. Yurakov Beds (347375 m) dark-grey clays with abun-

dant Spiratella (Limacina) lies under the grey Tschokrakian

limestones. The Yurakov Beds start at a depth of 347 m (Fig.

4). In the upper part of the clays up to a depth of 347 m a poor

association of nannoplankton is represented by the following

species: Coccolithus pelagicus, Calcidiscus leptoporus, Cycli-

cargolithus floridanus, Braarudosphaera bigelowii subsp.

parvula, Rhabdosphaera sicca, Helicosphaera carteri.

2. Tarkhan Beds (375384 m). In this interval a comparable

association was observed with the same in the beds with

Amussium denudatum. The characteristic species are: Spheno-

lithus heteromorphus, S. cf. abies, S. moriformis, Heli-

cosphaera carteri, H. sp., H. intermedia, Cyclicargolithus

404 ANDREYEVA-GRIGOROVICH and SAVYTSKAYA

floridanus, Calcidiscus leptoporus, Rhabdosphaera sicca,

Braarudosphaera bigelowii, Reticulofenestra pseudoumbili-

cus, Pontosphaera multipora.

3. Kamyshlak Beds (384398.5 m) in dark-grey to

black non-carbonate clays the nannoplankton association is

very poor.

The Azov coast Tarkhanian deposits can be clearly divided

into three lithological successions, westwards and southwards

of Tarkhan cape there is not sharp difference. They are repre-

sented by monotonous dark-grey clays there. Nannoplankton

associations here are of the same type and age as those from

the stratotype area. Absence of the marl beds in the Tarkhan

sequence in this territory is probably caused by the deeper con-

ditions of sedimentation, in which deposition of flaky dark-

grey and black clays took place (Nosovsky et al. 1976).

Paleoecology of the Tarkhanian sedimentary area

Nannoplankton can be considered as an indicator of the pe-

riods of marine communications between epicontinental seas

and the World ocean. Nannoplankton occurrences in the exact

outcrops of the Kerch Peninsula show direct connections of

the Eastern Paratethys and the World ocean at that time. The

Tarkhanian deposits therefore point out to marine connections

between the Eastern Paratethys and the World ocean. The

study of the nannoplankton association allows us to ascertain

stenohaline conditions, for example normal marine salinity by

presence of Helicosphaera spp., Discoaster spp., Rhab-

dosphaera spp., Sphenolithus spp. and so on, which is in good

agreement with the observation of Muzylov & Golovina

(1987), about the closing and reopening of the marine seaway

between the Eastern Paratethys and World ocean.

The Early Tarkhanian transgression caused considerable

changes in the regime and character of the sedimentation in

the Eastern Paratethys. The accumulation of non-carbonate

clay beds (clays of the Maikop clays) pass into the carbonate

marl deposition bearing abundant remnants of planktonic and

benthic organisms (marls with A. denudatum Tarkhan

Beds). The Tarkhanian sedimentary area in the Eastern Parat-

ethys extended from Bulgaria in the west to Western Turkme-

nia in the east and from Central Ukraine in the north to Kopet-

dag in the south (Goncharova 1991). The abundant and

various associations of nannoplankton with Sphenolithus spp.,

Helicosphaera spp., Rhabdosphaera spp. from Tarkhanian

marls with A. denudatum and from lower part of Yurakov

(Spirialis) Beds witness a wide connection with the World

ocean and characterize this sedimentary area as a normal ma-

rine area. The basin was possibly connected with the Western

Paratethys in the North-West and with the eastern Mediterra-

nean or Indian Ocean in the South-East. The same marine con-

ditions documented by a coeval nannoplankton association

were also observed in the lower part of the Yurakov Beds with

Spirialis (Limacina).

In the Late Tarkhanian sedimentary area (the time of accu-

mulation of upper part of the Spirialis clays), the quantity of

nannoplankton gradually, but very quickly diminished. Rare

Coccolithus pelagicus, Cyclicargolithus floridanus, Calcidis-

cus leptoporus, Braarudosphaera bigelowii occur, and at the

top of the succession the quantity of Perforocalcinella fusifor-

mis increased. These facts suggest a decrease of the inflow of

oceanic waters, this inflow remains on the level sufficient for

Fig. 4. Distribution of nannoplankton in the Sokol-60 Borehole.

NANNOPLANKTON OF THE TARKHANIAN DEPOSITS 405

existence of nannoplankton. Generally, the late Tarkhanian

sedimentary area can be considered marine, but with salinity

deacrease caused possibly by partial isolation of the area or by

strong terrigenous input.

Age and correlation of Tarkhanian deposits

In spite of the fact that Tarkhanian deposits are widely de-

veloped in the Euxine-Caspian area and are varied in litholog-

ical character, there is not a uniform opinion about the age and

correlation of them among the specialists on different groups

of fauna, as well as between the specialists on one group.

On the basis of occurrence of Helicosphaera ampliaperta in

the marls with A. denudatum at the base of the Yurakov (Spiri-

alis) Beds Bogdanovich (Nosovsky & Bogdanovich 1984) as-

signed these deposits to the NN4 Zone and correlated them

with the Karpatian Stage of the Western Paratethys.

Nosovsky, on the basis of Bogdanovichs data attributed the

Kamyshlak Beds and Tarkhan Beds to the NN4 Zone and the

Yurakov Beds to the NN5 Zone and correlated them with the

Lower Langhian Stage of the Mediterranean (Nosovsky 1998).

Minashvili distinguished the lower part of the zone NN5

(Sphenolithus heteromorphus acme) among Tarkhanian de-

posits of Georgia and correlated them with the uppermost

part of the Karpatian and the lowermost part of the Badenian

stages, of the central Paratethys or with the top of the Burdiga-

lian and the base of the Langhian Stage (Minashvili 1992).

The authors opinion is that nannoplankton associations

from the Tarkhan Beds and Yurakov Beds correspond to the

NN5 Zone Sphenolithus heteromorphus. Unfortunately, be-

cause of rare occurrences of nannofossils in the underlying

(Kamyshlak Beds) and overlying (top of the Yurakov Beds

and beds of the Tschokrakian Stage deposites) beds, it was im-

possible to follow the lower and upper boundaries of the zone.

According to the nannoplankton biozonation (Fornaciari et

al. 1996), the boundary between Langhian and Burdigalian in

the Mediterranean area and the boundary between Carpathian

and Badenian are inside the zone NN4 in the Western Parat-

ethys (Berggren et al. 1995). Therefore, the Tarkhanian depos-

its, more exactly both Tarkhan and Yurakov (Spirialis) Beds

containing nannoplankton of the NN5 Zone are correlated

with the Early Badenian and Langhian. The same associations

of nannoplankton with abundance of Sphenolithus heteromor-

phus, Calcidiscus spp., Discoaster spp. have been found in the

Badenian of the Moravian and Lower Austrian sediments

(vábenická & Ètyroká 1999) (Fig. 5). Presence of planktonic

foraminifers characteristic for the zone N8 Globigerina

bollii, Globigerinoides bisphaericus, Praeorbulina aff. transito-

ria in both Tarkhan and lower Yurakov (Spirialis) Beds (Ivano-

va 1999) also allow us to correlate the Tarkhanian Stage with

the lower part of the Badenian Stage in the Central Paratethys.

Conclusions

1. The studied sequences of the Tarkhanian deposits in

Kerch Peninsula are represented by shallow-water limestones

and marls with A. denudatum as well as by deepwater clays in

the typical Maikop facies.

Fig. 5. Comparison of nannoplankton zones and ranges of the most important taxa in stratotype area of Tarkhanian deposits of Kerch

Peninsula (Eastern Paratethys) and Carpathian/Badenian sediments in Moravia and Lower Austria (Central Paratethys vábenická &

tyroká 1999) and Langhian stratotype area in Italy (Mediterranean area Fornaciari et al. 1996).

406 ANDREYEVA-GRIGOROVICH and SAVYTSKAYA

2. Characteristic and abundant associations of nannoplank-

ton from the Tarkhan Beds and the lower part of the Spirialis

Beds document a period of connection of the Early Tarkhanian

sedimentary area with the Western Paratethys in the north-

west and Indo-Pacific in the south-east and characterize this

area as marine with normal salinity.

3. The sharp decrease of the nannoflora at the end of the

Tarkhanian time (upper part, the Yurakov Beds with Spirialis)

may be explained by gradual cessation of the marine connec-

tion of the area and its gradual isolation.

4. The deposits of the Tarkhan Beds and Yurakov Beds

(Spirialis clays) contain nannoplankton of the NN5 Zone

(Sphenolithus heteromorphus) and allow us to correlate the

Tarkhanian Stage with the Early Badenian Stage of the West-

ern Paratethys and Langhian Stage of the Mediterranean area.

List of nannoplankton species

mentioned in this paper

Coccolithus pelagicus (Wallich) Schiller 1930

Calcidiscus macintyrei Bukry & Bramlette 1969

C. leptoporus (Murray & Blackmann) Loeblich & Tappan 1978

Coronocyclus nitescens (Kamptner 1963) Bramlette & Wilcox-

on1967

Cyclicargolithus floridanus (Roth & Hay) Bukry 1971

Discoaster variabilis Bramlette & Riedel 1963

Helicosphaera carteri (Wallich 1887) Kamptner1954

H. granulata (Bukrz & Percival1971) Jafar & Martini1975

H. waltrans Theodoridis

H. cf. mediterranea Muller 1981

H. cf. walbersdorfensis Muller 1974
H. intermedia (Martini) Hay & Mohler 1967

Sphenolithus heteromorphus Deflandre 1953

S. moriformis (Bronnimann & Stradner1960) Bramlette & Wilcox-

on 1967

S. compactus Backman1980.

S. abies Deflandre 1954

S. cf. abies

Braarudosphaera bigelowii (Gran & Braarud 1935) Deflandre 1947

B. bigelowii subsp. parvula Stradner 1963

Rhabdoshpaera sicca Stradner 1961

Reticulofenestra pseudoumbilicus (Gartner 1967) Gartner 1969

R. minuta Roth 1970

Thoracosphaera saxea Stradner 1961

T. heimii (Lohmann 1919) Kamptner 1941

Triquetrorhabdulus rugosus Bramlette & Wilcoxon 1967

Pontosphaera discopora Schiller 1925

P. multipora (Kamptner 1948) Roth 1970

Perfocalcinella fusiformis Bona 1966

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