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GEOLOGICA BALCANICA, 43. 1 – 3, Sofia, Dec. 2014, p. 63-76. Tithonian and Lower Berriasian calpionellid against ammonite biostratigraphy of the Dvuyakornaya Formation in eastern Crimea Egor Platonov1, Iskra Lakova2, Silviya Petrova2, Vladimir Arkadiev3

FGU NPP "Geologorazvedka", Saint-Petersburg, Russia; e-mail: platonov_egor@inbox.ru 2Geological Institute, Bulgarian Academy of Sciences, Sofia, Bulgaria; e-mail: lakova@geology.bas.bg, sylviya_p@geology.bas.bg 3Saint-Petersburg State University, Saint Petersburg, Russia; e-mail: arkadievvv@mail.ru (Accepted in revised form: November 2014)

Abstract. The Dvuyakornaya Formation in eastern Crimea of late Kimmeridgian to Berriasian age represents a thick flysch-like succession of clays, marls and less common limestones. The ammonite zonation includes incomplete record from the Beckeri Zone in the uppermost Kimmeridgian up to the Jacobi Zone in the Lower Berriasian. Two main sections have been micropalaeontologically studied – the Dvuyakornaya Buhta and the Cape Svyatogo Ili’i. Eighteen calpionellid species of the genera Longicollaria, Chitinoidella, Daciella, Dobeniella, Popiella, Praetintinnopsella, Tintinnopsella, Crassicollaria and Calpionella have been found. The calpionellid zones Chitinoidella (with Dobeni and Boneti subzones), Crassicollaria and Calpionella (with Alpina and Elliptica subzones) are described and directly correlated to the existing ammonite biostratigraphy. The Dobeni Subzone corresponds to a part of the barren interval between the ammonite Hybonotum and Microcanthum zones, the Boneti Subzone – to the Microcanthum Zone, and the Crassicollaria Zone – to the Durangites Zone p.p. and Jacobi Subzone p.p. The boundary between the Crassicollaria and Calpionella zones is within the Jacobi Subzone. In the Berriasian, the Alpina Subzone has been correlated to the Jacobi and Grandis subzones, and the Elliptica Subzone – to upper part of the Grandis Subzone that was characterized in the Dvuyakornaya Formation by diverse ammonite faunas of the “Feodosiya Marlstones”. Chitinoidellids of the Dobeni Subzone for the first time determine late Early Tithonian age in the area. Calpionellid to ammonite correlation of the Dvuyakornaya Formation is discussed in the light of previous direct correlations between macro- and microfossil biostratigraphy of the Tithonian and the Lower Berriasian in the Tethyan Realm.

Platonov, E., Lakova, I., Petrova, S., Arkadiev, V. 2014. Tithonian and Lower Berriasian calpionellid against ammonite biostratigraphy of the Dvuyakornaya Formation in eastern Crimea. Geologica Balcanica 43 (1 – 3), 63-76.

Key words: Tithonian, Berriasian, calpionellids, ammonites, biostratigraphy, correlation, eastern Crimea.

INTRODUCTION

The Dvuyakornaya Formation crops out in the eastern Crimea nearby the town of Feodosiya and has been a subject of paleontological and biostratigraphic studies for many decades. Its age was determined as late Kim-meridgian to Berriasian on the basis of ammonite bio-stratigraphy (Arkadiev, Rogov, 2006; Arkadiev et al., 2006; Guzhikov et al., 2012; Arkadiev, Bogdanova, 2012). Taking into account that diverse fossil groups have already been thoroughly examined in the Dvuyakornaya Formation (e.g., ammonites, belemnites,

foraminifers, ostracods, organic-walled dinoflagellates), the study of calpionellids remained poor and incomplete.

Actually, the presence of calpionellids was mentioned by previous scholars. Vassoevich (1935) was the first who reported the find of Calpionella alpina in Crimea and Caucasus. Then Linetskaya (1968, 1971) provided more detailed description of calpionellids from the “Feodosiya Marlstone” packet (Jacobi Zone in the Berriasian). Later on, Sazonova, Sazonov (1984) determined two distinct calpionellid assemblages: a lower one consisting of mainly crassicollarians and

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characterized by Crassicollaria intermedia, and an upper one, typically Upper Berriasian, including the species Calpionellopsis oblonga, Calpionellopsis simplex, Tintinnopsella carpathica and Tintinnopsella longa. Taxonomic descriptions and illustration of the calpionellids are, however, absent from the article cited. Calpionellids of the Jurassic/Cretaceous boundary interval in the Dvuyakornaya Formation were studied by A.S. Shtennikova who determined a few species (Shtennikova, Arkadiev, 2011).

In 2010–2011 the sections around Feodosiya have been a subject of complex study by a team of scientists from the Saint-Petersburg State University, Moscow State University and Saratov State University. As a result of this multidisciplinary work, a continuous com-posite stratigraphic succession was proved, ammonite zones of the Upper Tithonian and Lower Berriasian were determined and a magnetostratigraphic subdivision tightly correlated to the biostratigraphy was proposed for the Tithonian/Berriasian boundary interval (Guzhi-kov et al., 2012). Recently, preliminary calpionellid results were reported by Platonov, Arkadiev (2011). In 2013, I. Lakova was also included in calpionellid biostratigraphic study. Additional species were identified and the biostratigraphy was refined (Platonov et al., 2013, 2014). Beside the Feodosiyan sections,

Berriasian calpionellids were also studied in the Tonas River basin in the eastern Crimea (Platonov, 2014).

The purpose of this article is: 1) to present vertical distribution of eighteen chitinoidellid and calpionellid species in the Tithonian and Lower Berriasian parts of the Dvuyakornaya Formation; 2) to correlate directly the calpionellid and ammonite occurrences; and 3) to discuss critical stratigraphical levels and zonations.

GEOLOGICAL SETTING

The Dvuyakornaya Formation represents a flysch-like alternation of predominant clays and subordinate limestones. The outcrops of this formation are located at Black Sea beach cliffs in the vicinities of Feodosiya and the most famous of them are the sections in the Dvuyakornaya Buhta and the Cape Svyatogo Ili’i (Figs. 1, 2). Four main sections of the formation were most usually described and studies on ammonites and microfossils were undertaken. In ascending chrono-stratigraphic order, they cover different parts of the interval from upper Kimmeridgian to Lower Berriasian. The section at Ordzhonikidze settlement corresponds to the uppermost Kimmeridgian and lowermost Tithonian, that in the Dvuyakornya Buhta – to the Tithonian, the

Fig. 1. Schematic drawing of part of the Crimean Peninsula (A) with studied area nearby Feodosiya and schematic drawing of the Feodosiya area (B) with the position of the sections studied and discussed (after Guzhikov et al., 2012, modified): 1 – upper Kimmeridgian–Lower Tithonian at the Ordzhonikidze secton; 2 – Lower and Upper Tithonian at the Dvuyakornaya Bay (outcrops 2901, 2922–2924); 3 – Lower Berriasian at the Cape Svyatogo Ili’i (outcrop 2456); 4 – Upper Tithonian–Lower Berriasian at the Cape Feodosiyskiy area (outcrops 2920–2921).

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Fig. 2. Location map (A) and geological map (B) (after Kazantsev et al., 1989, modified)of the Feodosiyan area and Dvuyakornaya Bay showing studied outcrops of Dvuyakornaya Formation at Ordzhonikidze (1), Dvuyakornava Buhta (2), Cape Svayatogo Ili’i (3), and Cape Feodosiyskiy sections (4). section at the Cape Feodosiykiy – to the uppermost Tithonian/lowermost Berriasian, and the outcrops at the Cape Svyatogo Ili’i – to the Lower Berriasian.

In the section at approximately 2 km north of the Ordzhonikidze settlement, Arkadiev, Rogov (2006) defined two successive ammonite horizons at the Kimmeridgian/Tithonian boundary – the lower one corresponding to the Beckeri Zone, and the upper one

representing a biostratigraphic correlative of the Hybonotum Zone. Thus, those authors determined late Kimmeridgian age of the base of Dvuyakornaya Formation.

The section of Dvuyakornaya Buhta (Figs. 1, 2) is famous for more than a century but modern reliable description, sedimentological studies, critical reasses-sment of previous views, new biostratigraphic data and magnetostratigraphy were provided just recently (Arkadiev, 2004, 2011; Arkadiev et al., 2006; Arkadiev, Bogdanova, 2012; Guzhikov et al., 2012). Arkadiev (2004) reported the find of Oloriziceras cf. schneidi Tavera, the first Upper Tithonian ammonite in the Dvuyakornaya Formation. Later, Paraulacosphinctes cf. transitorius (Oppel) and Paraulacosphinctes cf. senoides Tavera from a higher level of the Upper Tithonian have also been found (Arkadiev, 2011; Arkadiev et al., 2006).

The section at the Cape Feodosiyskiy was studied as a link between the Tithonian and Lower Berriasian outcrops. The find of the Berriasian ammonite Delphinella cf. tresannensis Le Hégarat suggests that the base of Jacobi Zone can be traced within this section (Arkadiev, Bogdanova, 2012; Guzhikov et al., 2012).

The upper part of the Dvuyakornaya Formation crops out at the Cape Svyatogo Ili’i (Figs. 1, 2) and was assigned to the Lower Berriasian (Arkadiev, 2003; Arkadiev, Bogdanova, 2004; Bogdanova, Arkadiev, 2005; Arkadiev et al., 2008). Whereas the Feodosiyan Marlstones were known long ago with its ammonites of the Grandis Subzone, Arkadiev (2003) found at 60 m below ammonites of the Jacobi Subzone.

MATERIAL AND METHODS

During the field work, a total of 240 stratigraphic levels have been sampled for micropalaeontological study of calpionellids. The thickness of the Dvuyakornaya Formation (without its upper Kimmeridgian and lowermost Tithonian parts) is estimated to 350 m. E.S. Platonov prepared and examined over 800 thin sections from the sampled levels. Nineteen productive thin sections have been further studied in the Geological Institute, Sofia, under transmitted light Jenaval microscope.

The Dvuyakornaya Formation has appeared to be fairly favorable for calpionellid study. The calpionellids are rare and of moderate state of preservation.

All the thin sections studied are stored in the “Acad. F.N. Chernishev” Central Research and Geological Prospecting Museum in Saint-Petersburg, in collection under № 13220.

DESCRIPTION OF THE SECTIONS

Dvuyakornaya Buhta Section (Tithonian)

The section is located in the Dvuyakornaya Buhta (Figs. 1, 2) and it was previously described by Arkadiev et al.

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(2006), Arkadiev, Bogdanova (2012) as outcrop 2901 (packets 1–9). The packets 10–12 crop out in the section 2922–2924 of Arkadiev et al. (2006), Arkadiev, Bogdanova (2012). Lower parts of the Dvuyakornaya Formation crop out in these two sections (Fig. 5) that were assigned to the Tithonian by Arkadiev, Rogov (2006) and Arkadiev, Bogdanova (2012).

Thirteen packets (members) have been sampled for micropaleontology and the results are shown below (Fig. 3). From bottom to top these packets are as follows:

Packet 1 (12 m). Thin alternation of greenish gray fine laminated clays with brown siderite concretions and plant detrite, sandy clays and pinkish limestones. Holcophylloceras sp., Haploceras sp., Lytoceras sp. and Ptychophylloceras sp. were reported at 1 m above the base of packet (Arkadiev et al., 2006).

Packet 2 (8 m). Gray clays. Packet 3 (13.5 m). Alternation of dark green to gray

clays and cream coloured fine bioclastic limestones. Haploceras sp. and Lytoceras sp. The first representatives of the family Chitinoidellidae have been recorded in the base of this packet (sample 140) – Longicollaria dobeni and Popiella oblongata. The former species indicates the Dobeni Subzone of the Chitinoidella Zone, i.e. the uppermost Lower Tithonian.

Packet 4 (12 m). Alternation of dark green to gray clays, siltstone lenses and pinkish gray fine bioclastic limestones. Ptychophylloceras sp.

Packet 5 (15 m). This packet is almost the same as the underlying one with except of the presence of a 0.4 m thick bed of creamy detritic limestone at the top. No ammonites and calpionellids were found.

Packet 6 (15 m). Mainly greenish gray clays. No ammonites or calpionellids.

Packet 7 (16 m). Alternation of greenish gray fine laminated clays, cream coloured and brown bioclastic limestones and rare interbeds of gray detrital calcareous sandstones. Arkadiev (2004), and Arkadiev, Rogov (2006) reported Oloriziceras cf. schneidi Tavera and Ptychophylloceras sp. from a level at 2 m below the top of packet 7. O. cf. schneidi indicates the Simplisphinctes Subzone of the Microcanthum Zone. Chitinoidella boneti is here documented in sample 141 from the same level of the ammonite finds. Thus, the base of the Boneti Subzone of Chitinoidella Zone is to be traced in this packet.

Packet 8 (10 m). Mainly gray clays. No ammonites or calpionellids.

Packet 9 (20 m). Irregular alternation of greenish gray clays, creamy bioclastic limestones and brown sideritic interlayers. The ammonites Paraulacosphinctes cf. transitorius (Oppel) and Paraulacosphinctes cf. senoides Tavera were reported by Arkadiev (2011) from this section, and by Arkadiev, Rogov (2006) from coeval outcrops elsewhere in the area, 1 km SE of the Yuzhnoe settlement. These ammonites indicate the Upper Tithonian Microcanthum Zone. The chitinoidellids Chitinoidella boneti and Chitinoidella elongata from the sample 143 are characteristic of the Boneti Subzone.

Packet 10 (15 m). The packet is quite similar to the underlying one but without sideritic interlayers. No ammonites or calpionellids.

Packet 11 (40 m). Mainly dark gray to greenish clays intercalated by thin layers of ferruginized bioclastic limestone and siderite. Ptychophylloceras sp. occurs in the base of packet whereas Neoperisphinctes cf. falloti (Kilian) was reported from the topmost part (Arkadiev in Guzhikov et al., 2012). The latter species suggests the presence of the Durangites Zone. A series of microfossil samples yielded the following calpionellids: sample 135 – Chitinoidella boneti, Chitinoidella elongata, Dobeniella cf. bermudezi; sample 132 – Calpionella alpina, Crassicollaria parvula; sample 144 – Chitinoidella boneti, Daciella danubica, Tintinnopsella carpathica, Tintinnopsella remanei; sample 240 – Crassicollaria parvula; sample 142 (i.e. the level with N. cf. falloti) – Chitinoidella boneti, Praetintinnopsella andrusovi, Dobeniella cubensis, Calpionella alpina. The level of sample 132 marks the base of the Massutiniana Subzone.

Packet 12 (40 m). Mainly dark gray clays interbeded by thin layers of gray detritic limestones and brown siderites. Abundant big-sized land plant remains are characteristic of this packet. No ammonites were found. However, in the outcrop Cape Feodosiyskiy, Delphinella cf. tresannensis Le Hégarat was reported from the top of the same packet (Arkadiev, Bogdanova, 2012; Guzhikov et al., 2012); this species indicates the Jacobi Subzone of the Jacobi Zone, i.e. the base of Berriasian. The calpionellid record is very scarce: Tintinnopsella carpathica in the samples 241 and 244 and Crassicollaria cf. brevis in the sample 243. Crassicollaria cf. brevis that indicates the Massutiniana Subzone has been found in the mid of the packet 12 below the level of Delphinella cf. tresannensis Le Hégarat.

Member 13. A thick bed of light brown massive organogenic to extraclastic limestone with a sharp upper surface showing wash-out features. This is a marker horizon which is also traceable in the outcrop 2456 (Cape Svyatovo Ili’i) where it is designated as the member 1 (see Fig. 4) at the base of Berriasian. This bed corresponds to the uppermost part of the Crassicollaria Zone.

Cape Svyatogo Ili’i Section (Lower Berriasian)

The section is located in the vicinities of the Cape Svyatogo Ili’i (Figs 1, 2). The stratigraphic succession is the same as in the outcrops 2920 and 2921 at the Cape Feodosiyskiy as it was described in Guzhikov et al. (2012). Previous ammonite biostratigraphy determined Early Berriasian age, i.e. the Jacobi and Grandis sub-zones of the Jacobi Zone (Arkadiev et al., 2006). From bottom to top the following 7 packets (members) have been sampled for micropaleontological study (Figs 4, 5):

Member 1. This is a thick limestone bed that is also traceable in the outcrops 2922–2924 in the Dvuyakornaya Buhta section and in the Berriasian part at Cape Feodosiyskiy section (outcrops 2920 and 2921). This limestone reference bed was determined as channel turbidite facies (Guzhikov et al., 2012). The member thickness in the Cape Svyatogo Ili’i section exceeds 3 m. Arkadiev (2003) reported the find of Haploceras sp. Only single Crassicollaria massutiniana have been determined in the sample 137. In the absence of Calpionella alpina, this packet is interpreted as corresponding to the Massutiniana Subzone. The member 1 equals with the member 13 in the previous section.

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Fig. 3. Columnar section of the Tithonian part of Dvuyakornaya Formation at the Dvuyakornaya Bay. Lithology and packets according to Arkadiev et al. (2006) and Arkadiev, Bogdanova (2012); ammonite findings after Arkadiev (2004, 2011); * - ammonite find from elsewhere (see in the text).

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Fig. 4. Columnar section of the Lower Berriasian part of Dvuyakornaya Formation at the Cape Svyatogo Ili’i. Lithology and packets according to Arkadiev (2003) and Arkadiev et al. (2006); ammonite findings after Arkadiev (2003), Arkadiev, Bogdanova (2004, 2005), Bogdanova, Arkadiev (2005).

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Packet 2 (16 m). Mainly gray calcareous clays interbedded with light beige limestones. Arkadiev (2003) reported Berriasella chomeracensis (Toucas), Fauriella cf. floquinensis Le Hégarat, Ptychochylloceras cf. semisulcatum (d’Orbigny), Berriasella sp. and Haploceras sp. from a level at 4 m above the base of packet (Jacobi Subzone). Upwards, at 10 m above the base, Delphinella cf. obtusenodosa (Retowski) and Pseudosubplanites cf. lorioli (Zittel) were found that gave ground to trace the base of the Grandis Subzone within this packet (Bogdanova, Arkadiev, 2005; Arkadiev, Bogdanova, 2012). Calpionella alpina has been found in the sample 138, and Calpionella alpina, Crassicollaria parvula, Crassicollaria massutiniana and Tintinnopsella carpathica – in the sample 133 (Fig. 4). The packet 2 corresponds to the base of Alpina Subzone of the Calpionella Zone.

Packet 3 (8 m). Light green to gray clays with rare centimeter-scale light brown bioclastic limestone interbeds. No ammonite or calpionellid finds.

Packet 4 (17 m). Alternation of greenish gray clays and light brown bioclastic limestones. Haploceras sp. and Hap-loceras cf. carachtheis (Zeuschner) were found (Arkadiev, 2003; Arkadiev, Bogdanova, 2012). Calpionella alpina occurs both at the base and the top of this packet, (samples 245, 246, and 247). The packet 4 corresponds to the Alpina Subzone.

Packet 5 (13 m). Mainly greenish gray clays with interbeds of cream coloured bioclastic limestones. No ammonites. Only Calpionella alpina has been determined in the sample 248.

Packet 6. Predominantly greenish gray clays with rare interbeds of dark brown bioclastic limestones. No ammonites or calpionellds.

Packet 7 (12.5 m). These are the so-called “Feodosiya Marlstones” which differ from the underlying packet by the presence of thick clayey beds and marl lenses. Ammonites are found in five of the six marl levels as follows: in the first level – Ptychophylloceras sp., in the second level – Delphinella sp. and Biasaloceras liebigi (Oppel), in the third level – Delphi-nella crimense (Burckhardt), Retowskiceras sp., Pseudo-subplanites sp., Holcophylloceras tauricum (Retowski), and Protetragonites tauricus (Kouljinskaia-Voronetz), in the fourth level – Protetragonites tauricus (Kouljinskaia-Voro-netz), Biasaloceras sp., Haploceras carachtheis (Zeuschner), Pseudosubplanites ponticus (Retowski), Pseudosubplanites combesi Le Hégarat, Pseudosubplanites lorioli (Zittel), and Ptychophylloceras semisulcatum (d’Órbigny), and in the fifth level – Pseudosubplanites lorioli (Zittel), Ptychophylloceras semisulcatum (d’Orbigny), Pseudosubplanites grandis (Mazenot), and Delphinella cf. crimense (Burckhardt). The ammonite fauna is quite diverse and suggests attribution to the Grandis Subzone of the Jacobi Zone according to Arkadiev et al. (2006) and Arkadiev, Bogdanova (2005, 2012). Crassicollaria parvula, Calpionella elliptica, Calpionella minuta, Tintinnopsella carpathica and Tintinnopsella longa have been recorded in this packet from the sample 131. The upper half of the Packet 7 is thus assigned to the Elliptica Subzone of the Calpionella Zone.

Fig. 5. Field photographs showing different levels of the Tithonian and Lower Berriasian of Dvuyakornaya Formation. 1. Lower Tithonian, lower part of the formation, Dvuyakornaya Buhta section, packets 1-6 in Fig. 3, Dobeni Subzone; 2. Basal Berriasian, Conglomeratic limestone reference bed, Dvuyakornaya Buhta section, member 1 in Fig. 4, Alpina Subzone; 3. Tithonian–Berriasian boundary transition, Dvuyakornaya Buhta section. 4. Lower Berriasian “Feodosiya Marls”, upper part of the Dvuyakornaya Formation, Cape Svyatogo Ili’i section, packet 7 in Fig. 4, Elliptica Subzone.

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CALPIONELLID BIOSTRATIGRAPHY

The micropalaeontological study of the Dvuyakornaya Formation around Feodosiya has revealed the occur-rence of eighteen chitinoidellid and calpionellid species in the Tithonian and Lower Berriasian strata (Fig. 6). Systematic description and synonymic lists were published in Platonov et al. (2014). A biostratigraphic succession is here described of the Chitinoidella (Dobeni and Boneti subzones), Crassicollaria and Calpionella zones, the latter being represented by its lower Alpina and upper Elliptica subzones (Figs 3, 4). Calpionellid biostratigraphy follows widely accepted zonal schemes of the Tithonian and Berriasian (e.g. Remane, 1963; Remane et al., 1986; Pop, 1994, 1997b, 1998b; Reháková, Michalík, 1997; Lakova et al., 1999; Michalík, Reháková, 2011; and Lakova, Petrova, 2013).

Although the Dvuyakornaya Formation represents a stratigraphically expanded succession of the Tithonian and Lower Berriasian, the calpionellid Praetintin-nopsella Zone and Remanei and Remaniella subzones have not been proved in this study. The boundaries of the calpionellid zones and subzones described below are rather tentative. Despite of the huge number of thin sections examined we found the calpionellids to be sporadically distributed in the sections.

Chitinoidella Zone

Dobeni Subzone

Longicollaria dobeni has been recorded in the packet 3 of the Dvuyakornaya Buhta section. This species occurs in the latest Early Tithonian. Its first occurrence is the biostratigraphic marker that defines the base of Chitinoidella Zone and the Dobeni Subzone (the packets 3–7 in Fig. 3). Even scarce, the chitinoidellid record suggests the assigning of packets 1–7 to the Lower Tithonian. Downward the succession of the Dvuyakornaya Formation, below the packet 1, the ammonite Hybonotum Zone of the lowermost Tithonian was determined (Arkadiev, Rogov, 2006).

Boneti Subzone

Chitinoidella boneti has been recorded in the packets 7, 9, and 11 in the section Dvuyakornaya Buhta, thus indicating the base of Boneti Subzone and the base of Upper Tithonian in the packet 7. In the packets 9 and 11, Chitinoidella elongata occurs and it is also characteristic of the Boneti Subzone. The presence of Dobeniella cf. bermudezi is established only in the upper part of the packet 11. The Boneti Subzone correlates well with the ammonite Microcanthum Zone (Simplisphinctes Subzone). That was documented on the basis of Oloriziceras cf. schneidi Tavera described by Arkadiev, Rogov (2006) from the packet 7, and the presence of Paraulacosphinctes cf. transitorius (Oppel) and Paraulacosphinctes cf. senoides Tavera from

uppermost part of packet 9 in the same outcrop of Dvuyakornaya Formation.

Only at the top of the packet 11 Praetintinnopsella andrusovi has been recorded. However, separate Praetintinnopsella Zone has not been determined in the zonal scheme since the rare specimens of Pr. andrusovi have been found reworked above the characteristic calpionellids of the overlaying Crassicollaria Zone.

Crassicollaria Zone

In the Tethyan Realm, the base of Crassicollaria Zone is traced at the first occurrence of the hyaline calpionellids of the family Calpionellidae. Normally, these are the species Tintinnopsella carpathica and Tintinnopsella remanei that mark the base of Crassicollaria Zone. The scarcity of calpionellids has not allowed clear recognition of subzones. Tintinnopsella carpathica occurs in the middle of the packet 11 in the outcrops 2922–2924. A single specimen of Tintinnopsella remanei has been found at 3.5 m above Crassicollaria parvula and Calpionella alpina. Although the latter two species are longer-ranging forms occurring upwards in the Berriasian, their first record in the middle of the packet 11 marks the base of the Massutiniana Subzone (Crassicollaria Zone). In the packet 12, in the outcrops 2922-2924, Crassicollaria cf. brevis and Tintinnopsella carpathica mark also the Massutiniana Subzone. Since all microfossils in the bioclastic limestones were transported from elsewhere in the flysch depositional area, reworking of some microfossils in younger strata is likely. Such is the case with Daciella danubica, Dobeniella cubensis, Tintinnopsella remanei, Praetintinnopsella andrusovi, and the higher record of Chitinoidella boneti in the packet 11. Crassicollaria Zone corresponds to the ammonite Durangites Zone indicated by the presence of Neoperisphinctes cf. falloti (Kilian) (Guzhikov et al., 2012).

The packet 12 is considered as upper part of the Crassicollaria Zone. This packet is of critical importance since the Berriasian ammonite Delphinella cf. tresannensis Le Hégarat was reported from its uppermost part in the section of the Cape Feodosiyskiy, below the top of the Crassicollaria Zone (Fig. 3) (Guzhikov et al., 2012; Arkadiev, Bogdanova, 2012). The member 1 in the Cape Svyatogo Ili’i section is here also considered as the Crassicollaria Zone.

Calpionella Zone

The base of the Calpionella Zone normally corresponds to the base of Berriasian in the Tethyan Realm. The base of this zone is defined at the sudden “explosion” of the small spherical variety of Calpionella alpina. Tintinnopsella carpathica and Crassicollaria parvula are accompanying species. Due to facies features of the limestones studied, the low abundance, and the moderate state of preservation of calpionellids, determination of the “explosion of Calpionella alpina” is far from precise.

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Figure 6. Chitinoidellids and Calpionellids from the studied sections. Abbreviations: DBS – Dvuyakornaya Buhta section; CSIS – Cape Svyatogo Ili’i section. 1-2. Popiella oblongata Reháková, 1 – thin section 141, packet 7, DBS, Boneti Subzone, Chitinoidella Zone, base of the Upper Tithonian; 2 – thin section 140, packet 3, DBS, Dobeni Subzone, Chitinoidella Zone, top of the Lower Tithonian. 3. Longicollaria dobeni (Borza), thin section 140, packet 3, DBS, Dobeni Subzone, Chitinoidella Zone, top of the Lower Tithonian. 4-6. Chitinoidella elongata Pop, 4 – thin section 143, top of packet 9, 5-6 – thin section 135, base of packet 11, DBS, Boneti Subzone, Chitinoidella Zone, Upper Tithonian. 7-11. Chitinoidella boneti Doben, 7 – thin section 144, upper part of packet 11, DBS, Massutiniana Subzone, Crassicolaria Zone, Upper Tithonian; 8-11 – thin section 135, lower part of packet 11, DBS, Boneti Subzone, Chitinoidella Zone, Upper Tithonian. 12. Dobeniella cubensis (Furrazola Bermúdez), thin section 142, top of packet 11, DBS, Massutiniana Subzone, Crassicolaria Zone, Upper Tithonian. 13. Dobeniella cf. bermudezi (Furrazola Bermúdez), thin section 135, lower part of packet 11, DBS, Boneti Subzone, Chitinoidella Zone, Upper Tithonian. 14. Daciella danubica Pop, thin section 144, upper part of packet 11, DBS, base of Massutiniana Subzone, Crassicollaria Zone, Upper Tithonian. 15. Praetintinnopsella andrusovi Borza, thin section 142, top of packet 11, DBS, Massutiniana Subzone, Crassicollaria Zone, Upper Tithonian. 16. Crassicollaria cf. brevis Remane, thin section 243, packet 12, DBS, Massutiniana Subzone, Crassicollaria Zone, Upper Tithonian. 17-18. Crassicollaria parvula Remane, 17 – thin section 132, packet 11, DBS, base of Massutiniana Subzone, Crassicollaria Zone, Upper Tithonian; 18 – thin section 131, packet 7, CSIS, Elliptica Subzone, Calpionella Zone, Lower Berriasian. 19-20. Crassicollaria massutiniana (Colom), 18 – thin section 133, packet 2, 19 – thin section 137, base of member 1, CSIS, Alpina Subzone, Calpionella Zone, Lower Berriasian. 21. Tintinnopsella remanei Borza, thin section 144, upper part of packet 11, DBS, Massutiniana Subzone, Crassicollaria Zone, Upper Tithonian. 22. Tintinnopsella doliphormis (Colom), thin section 133, packet 2, CSIS, Alpina Subzone, Calpionella Zone, Lower Berriasian. 23-28. Tintinnopsella carpathica (Murgeanu & Filipescu), 23 – thin section 131, packet 7, CSIS, Elliptica Subzone, Calpionella Zone, Lower Berriasian; 24, 28 – thin section 133, packet 2, CSIS, Alpina Subzone, Calpionella Zone, Lower Berriasian; 25 – thin section 144, upper part of packet 11, 26 – thin section 244, upper part of packet 12, 27 – thin section 241, base packet 12, DBS, Massutiniana Subzone, Crassicollaria Zone, Upper Tithonian. 29. Tintinnopsella longa (Colom), thin section 131, packet 7, CSIS, Elliptica Subzone, Calpionella Zone, Lower Berriasian. 30-37. Variable morphology of Calpionella alpina Lorenz, 30 – thin section 132, packet 11, DBS, base of Massutiniana Subzone, Crassicollaria Zone, Upper Tithonian; 31-33 – thin section 133, packet 2, 34 – thin section 248, base of packet 5, 35 – thin section 245, base of packet 4, 36 – thin section 246, base of packet 4, 37 – thin section 247, upper part of packet 4, CSIS, Alpina Subzone, Calpionella Zone, Lower Berriasian. 38. Calpionella minuta Houša, thin section 131, packet 7, CSIS, Elliptica Subzone, Calpionella Zone, Lower Berriasian. 39. Calpionella elliptica Cadisch, thin section 131, packet 7, CSIS, Elliptica Subzone, Calpionella Zone, Lower Berriasian.

Alpina Subzone

At the base of the Alpina Subzone the species C. alpina, T. carpathica and Cr. parvula occur together with the last specimens of Cr. massutiniana. The ammonites Delphinella cf. obtusenodosa (Retowski) and Pseudosubplanites cf. lorioli (Zittel) from the same stratigraphical level at the Cape Svyatogo Ili’i section (Arkadiev, Bogdanova, 2012) suggest the presence of the Jacobi/Grandis subzone boundary interval within the packet 2 (Fig. 4). Upwards, only a few specimens of C. alpina have been determined in the packets 4–5. The boundary between the Crassicollaria and Calpionella zones is traced below in the packet 2 of the Cape Svyatogo Ili’i section (Fig. 4).

In many areas of the Tethyan Realm (e.g. Romania, Slovakia, Bulgaria, Italy, Austria) the Remaniella Subzone was recognized in the middle part

of the Calpionella Zone. However, the scarcity of material in the eastern Crimea is a reason why no representatives of the genus Remaniella have been found.

Elliptica Subzone

The lower part of this subzone is determined in the upper half of the “Feodosiya Marlstones”, packet 7 (Fig. 4). The base of the subzone is defined by first record of Calpionella elliptica. The association of the subzone is complemented by the presence of Crassicollaria parvula, Calpionella minuta, Tintinnopsella carpathica and Tintinnopsella longa. The Elliptica Subzone in the eastern Crimea corresponds to the top of the Dvuyakornaya Formation and to the upper part of the Grandis subzone that is typified by very diverse ammonite faunas.

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DISCUSSION

Correlation of ammonite and calpionellid zonations

Tithonian

According to the Geological Time Scale 2008, 2012 (Ogg et al., 2008; Ogg et al., 2012a), the Tithonian Stage is divided into the Lower and Upper substages, the Lower Tithonian incorporating the Lower+Middle Tithonian of previous scales. In the Tethyan Realm, the Lower Tithonian consists of five ammonite zones. From bottom to top these are: Hybonotum, Darwini, Semiforme, Fallauxi and Ponti/Burckhardticeras (Geyssant, 1997). The Upper Tithonian includes two ammonite zones – Microcanthum and Durangites. Direct correlations between ammonite and calpionellid events and zonations were published from Spain (Enay, Geyssant, 1975; Pruner et al., 2010), France (Cecca et al., 1989), Morocco (Benzaggagh, Atrops, 1997), and Tunisia (Boughdiri et al., 2006).

The base of the Chitinoidella Zone (and its lower Dobeni Subzone) is defined at the first occurrence of representatives of the family Chitinoidellidae. The lower boundary of this zone/subzone correlates with the ammonite Burckhardticeras Zone in Puerto Escaño section in Spain (Pruner et al., 2010). In many Tithonian sections of the Tethyan Realm the earliest species of Chitinoidellidae (from Dobeni Subzone) were not registered, only the upper Boneti Subzone of Chitinoidella Zone being documented. These are the sections in Spain (Enay, Geyssant, 1975), France (Cecca et al., 1989), Morocco (Benzaggagh et al., 2010), and Tunisia (Boughdiri et al., 2006). There, the base of the Boneti Subzone coincides with the base of the ammonite Microcanthum Zone, and thus with the base of the Upper Tithonian.

The base of the Crassicollaria Zone, as defined at the first occurrence of representatives of the family Calpionellidae with hyaline test wall (T. remanei, T. carpathica), is within the Upper Tithonian Micro-canthum Zone, and more precisely – between the Simplisphinctes and Transitorius subzones divided for example in Spain (Olóriz, Tavera, 1983) and Tunisia (Boughdiri et al., 2006). Pruner et al. (2010) documented in Spain the base of the Crassicollaria Zone somewhat higher within the Transitorius Subzone. Similar results were reported by Enay, Geyssant (1975) in Spain and by Cecca et al. (1989) in France.

The base of the calpionellid Intermedia= Massutiniana (A2+A3) Subzone is defined at the first occurrence of Calpionella grandalpina, previously known as the “big form of Calpionella alpina”. This bioevent coincides precisely with the base of the uppermost Tithonian ammonite Durangites Zone. Proofs are reported from France (Cecca et al., 1989), Spain (Pruner et al., 2010), Tunisia (Boughdiri et al., 2006) and Morocco (Benzaggagh et al., 2010).

The correlation of calpionellid zones/subzones with the existing ammonite biostratigraphy of the

Tithonian and Lower Berriasian in the Dvuyakornaya Formation fits well with the previous direct correlations summarized above. The Dobeni Subzone corresponds to a part of the barren interval between the ammonite Hybonotum and Microcanthum zones in the uppermost Lower Tithonian. The Boneti Subzone correlates to the Microcanthum ammonite zone, and the Crassicollaria Zone – to the Durangites Zone p.p. and Jacobi Subzone p.p.

Berriasian

The Berriasian Stage is divided into two substages, Lower and Upper (Ogg et al., 2008; Ogg et al., 2012b). The Lower Berriasian includes the ammonite Jacobi and Occitanica zones, whereas the Upper Berriasian typifies the Boissieri Zone. Calpionella Zone corresponds to the Lower Berriasian. Enay, Geyssant (1975) were the first who directly correlated the base of the Calpionella Zone (B) with the boundary between Durangites and Jacobi zones in sections of southeastern France. The critical work to show detailed correlation between calpionellid and ammonite bioevents throughout the Berriasian is that of Le Hégarat, Remane (1968). Precise coincidence between the lower boundaries of Jacobi and Calpionella zones was also documented in Tunisia (Boughdiri et al., 2006), and Morroco (Benzaggagh et al. 2010).

The correlation of the ammonite and calpionellid biostratigraphy of the Lower Berriasian part of the Dvuyakornaya Formation has revealed that the base of the Jacobi Zone falls within the upper part of the Crassicollaria Zone, as in the Le Chouet section in France (Wimbledon et al., 2013). The Alpina Subzone corresponds to the Jacobi and Grandis subzones, and the Elliptica Subzone – to upper part of the Grandis Subzone.

Possible criteria to define the base of Berriasian

Three principle stratigraphic levels in the Tithonian/ Berriasian boundary interval were extensively studied by teams of members of the Berriasian Working Group at the International Subcommission of Cretaceous Stratigraphy (Wimbledon et al., 2011): 1) the base of Calpionella Zone; 2) the FO of the nannofossil species Nannoconus steinmanni minor и Nannoconus kamptneri minor; and 3) the base of the magnetic chron M18r. Recently, summarizing the progress of the Berriasian Working Group, Wimbledon (2014) recommended that detailed and complex multidisciplinary studies should be focused on and around the bases of the Jacobi, Alpina and Grandis subzones.

In the Feodosiyan sections here described, the Grandis Subzone was characterized by diverse ammonite assemblages at the top of the Dvuyakornaya Formation but the base of this subzone was traced much below (Fig. 4). As for the Jacobi Subzone, its base was determined below the reference limestone bed (Figs. 3, 4). The base of the Alpina Subzone has been here traced a little higher than the reference limestone bed. It is

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worth mentioning that the Kilian group of the ammonite scholars of the Lower Cretaceous (Reboulet et al., 2014) recommended the Feodosiyan sections to be included in solving the problem to define the base of Berriasian.

CONCLUSIONS

Eighteen calpionellid species of the genera Longicol-laria, Chitinoidella, Daciella, Dobeniella, Popiella, Praetintinnopsella, Tintinnopsella, Crassicollaria and Calpionella have been found in the studied sections.

The calpionellid zones Chitinoidella (with Dobeni and Boneti subzones), Crassicollaria and Calpionella (with Alpina and Elliptica subzones) are described and directly correlated to the existing ammonite biostra-tigraphy. The Dobeni Subzone corresponds to a part of the barren interval between the ammonite Hybonotum and Microcanthum zones, the Boneti Subzone – to the Microcanthum Zone, and the Crassicollaria Zone – to the Durangites Zone p.p. and Jacobi Subzone p.p. Chitinoidellids of the Dobeni Subzone for the first time determine late Early Tithonian age in the area.

The boundary between the Crassicollaria and Calpionella zones is within the ammonite Jacobi Subzone.

In the Berriasian, the Alpina Subzone has been correlated to the Jacobi and Grandis subzones, and the Elliptica Subzone – to upper part of the Grandis Subzone that was characterized in the Dvuyakornaya Formation by diverse ammonite faunas of the “Feodosiya Marlstones”.

Acknowledgments

The authors are grateful to Andrjez Pszczołkowski (Warsaw) and Lubomir Metodiev (Sofia) for the critical review and useful suggestions that improved the manuscript.

Appendix. List of calpionellid species:

Family Chitinoidellidae Trejo, 1975 Chitinoidella boneti Doben, 1963 Chitinoidella elongata Pop, 1997 Daciella danubica Pop, 1998 Dobeniella cf. bermudezi (Furrazola Bermúdez, 1965) Dobeniella cubensis (Furrazola Bermúdez, 1965) Longicollaria dobeni (Borza, 1966) Popiella oblongata Reháková, 2002 Praetintinnopsella andrusovi Borza, 1969 Family Calpionellidae Bonet, 1956 Calpionella alpina Lorenz, 1902 Calpionella elliptica Cadisch, 1932 Calpionella minuta Houša, 1990 Crassicollaria cf. brevis Remane, 1962 Crassicollaria massutiniana (Colom, 1948) Crassicollaria parvula Remane, 1962 Tintinnopsella doliphormis (Colom) Tintinnopsella carpathica (Murgeanu & Filipescu, 1933) Tintinnopsella longa (Colom, 1939)

Tintinnopsella remanei Borza, 1969

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