Integrated Biostratigraphy of the Upper Cretaceous Abderaz Formation of the East Kopet Dagh Basin (NE Iran)

GEOLOGICA BALCANICA, 41. 1–3, Soﬁa, Dec. 2012, p. 21–37.

Integrated biostratigraphy of the Upper Cretaceous Abderaz Formation of the East Kopet Dagh Basin (NE Iran)

Meysam Shafiee Ardestani1, Mohammad Vahidinia1, Abbas Sadeghi2, José Antonio Arz3, Docho Dochev4

1 Faculty of Science, Department of Geology, Ferdowsi University of Mashhad, Mashhad, Iran; e-mail: [email protected] 2 Department of Geology, Faculty of Science, University of Shahid Beheshti, Tehran, Iran 3 Departamento de Ciencias de la Tierra (Paleontología) e Instituto de Investigación en Ciencias Ambientales (IUCA), Universidad de Zaragoza, C/ Pedro Cerbuna 12, E-50009 Zaragoza, Spain 4 Department of Geology, Paleontology and Fossil Fuels, Faculty of Geology and Geography, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria (Accepted in revised form: November2012)

Abstract. Based on planktonic foraminifera, inoceramids and echinoids, we present a detailed biostratigraphic analysis of the Abderaz Formation at the 606 m thick Padeha section, NE Iran. This sequence consists mainly of gray shales and marls with four levels of chalky limestones intercalated. The lower boundary of the Abderaz Formation with the Aitamir Formation is a paraconformity, while the upper boundary with the Abtalkh Formation represents a gradual transition. Fifty four species of planktonic foraminifera from 15 genera were identified, and five zones were recognized, namely: Whiteinella archaeocretacea (Bolli) Partial-Range- Zone; Helvetoglobotruncana helvetica (Sigal) Total-Range-Zone; Marginotruncana schneegansi (Dalbiez) Interval-Range-Zone; Dicarinella concavata (Brotzen) Interval-Range-Zone; and Dicarinella asymetrica (Sigal) Total-Range-Zone. Based on these data, the age of the Abderaz Formation is determined as earliest Turonian to earliest Campanian. Inoceramid bivalves Cremnoceramus walterdorfensis walterdorfensis (Andert) and Cremnoceramus deformis deformis (Meek) were identified in the uppermost Turonian and in the middle part of the early Coniacian, respectively. Echinocorys ex. gr. scutata and Cordiceramus sp. were recorded near the Coniacian/Santonian boundary.

Shafiee Ardestani, M., Vahidinia, M., Sadeghi, A., Arz, J.A., Dochev, D. 2012. Integrated biostratigraphy of the Upper Cretaceous Abderaz Formation of the East Kopet Dagh Basin (NE Iran). Geologica Balcanica 40(1–3), 21–37. Key words: Upper Cretaceous, Abderaz Formation, Biostratigraphy, Planktonic foraminiferal zonation, Inoceramids, NE Iran.

INTRODUCTION region; all formations are conformable, except for a few disconformities within the Cretaceous succession. These The Kopet Dagh sedimentary basin was formed after the can be related to epeirogenic movements in the basin. All Middle Triassic orogeny in northeast Iran (Afshar-Harb, formations thin out from north-west to south-east. They 1969). The basin was framed due to the faulting activ- were folded during the Late Alpine Orogeny and formed ity with approximately NW–SE trend. Four of these ma- the structural traps of the Khangiran and Gonbadli gas jor active basement faults have been recognized in the fields (Raisossadat and Moussavi-Harami, 2000). The central and western part of the basin. Sedimentation was Cretaceous sediments in the Kopet Dagh Basin are di- more or less continuous throughout the Middle Jurassic vided into nine different formations, composed mainly to Oligocene interval in the eastern part of the basin, of sandstones, conglomerates, mudstones, limestones where five major transgressive-regressive sequences and dolostones with subordinate evaporites. The thick- have been identified. Moussavi-Harami and Brenner ness of these sediments is normally more than 4000 m, (1992) concluded that subsidence in the eastern part of showing a prominent decrease to 2500 m in the eastern the basin was predominantly a result of sediment load- part of the basin (Shafiee Ardestani et al., 2011). The ing. There is no evidence of major tectonic activity in this Abderaz Formation is the major lithostratigraphic unit of

21 Late Cretaceous age in the Kopet Dagh Basin. It includes 6) Thick bedded white chalky limestones, 20 m thick. highly diverse and abundant micro- and macrofossils. 5) Thin bedded light gray shales, 44 m thick. Planktonic foraminiferal biostratigraphic analyses, 4) White chalky limestones, 7 m thick. together with the identification of invertebrate (mainly 3) Thin bedded light gray shales, 79 m thick. inoceramid) bio-events were conducted in order to pre- 2) White chalky limestones, 20 m thick. cise the age of the Abderaz Formation. It is based on 1) Thin bedded yellowish to gray marls, 40 m thick. the study of the Padeha section (Mashhad Province, NE The lower boundary of the Abderaz Formation with Iran), since this section was found to be well exposed and the Aitamir Formation is a paraconformity. Upwards, the containing enough micro- and macrofossils of high bios- Abderaz Formation passes gradually into the Abtalkh tratigraphic value to give a reliable age determination. Formation. The rocks contain common inoceramids, frequent echinoids, and some ammonites. Abundant planktonic foraminifers occur, especially in the chalky lime- LITHOSTRATIGRAPHY stones. The total thickness of the section is 606 m.

The Padeha section is located southeast of Mashhad. It crops out along the Mashhad-Sarakhs road, 25 kilo- METHODOLOGY meters east of type locality of the Abderaz Formation, and 2 kilometers from the Padeha rural road, near the The sampling density at the Padeha section was 3 me- Rakhshani region. The geographical position of the sec- ters, thus a total of 200 samples was collected. Samples tion is 60°44'39.6" E and 36°06'23.7" N (Fig. 1). were soaked in water with diluted hydrogen peroxide, The Abderaz Formation at Padeha section consists of and washed through 63 μm, 150 μm and 250 μm sieves. 11 lithological packets from top to bottom, namely (Fig. 2): About 200–300 foraminiferal specimenss were picked up 11) Thin bedded light gray shales, 28 m thick. from each sample in two size fractions (63–150 μm and 10) White chalk limestones, 18 m thick. >150 μm), determined, and mounted on microslides for 9) Thin bedded light gray marls, 300 m thick. permanent record and future revisions. 8) Thin bedded gray marls, 10 m thick. The most representative and the best preserved fora- 7) Thin bedded light gray shales, 40 m thick. miniferal specimens were selected for scanning electron

Fig. 1. Geological and geographical sketch-maps of the area of Padeha section (NE Iran)

22 microscopy (SEM), using a JEOL JSM 6400 SEM at of Ferdowsi University of Mashhad. Taxonomy is based the Microscopy Service of the Universidad de Zaragoza on Bolli (1957), Postuma (1971), Robaszynski and (Spain). They are illustrated in Figures 3–6. We also Caron (1979, 1995), Caron (1985), Loeblich and Tappan studied planktonic foraminiferal collection from the (1988), Nederbragt (1990), Ellis and Messina (1999), Abderaz Formation deposited at the National Museum and Premoli Silva and Verga (2004).

FORAMINIFERAL BIOSTRATIGRAPHY

The planktonic foraminiferal zonation here used is com- pared with other Tethyan biozonations (Fig. 7) (Barr, 1972; Premoli-Silva and Bolli, 1973; Vaptzarova, 1976; Sigal, 1977; Wonders 1980; Salaj, 1980, 1997; Robaszynski et al. 1984; Caron, 1985; Sliter, 1989; Abdel-Kireem et al., 1995; Robaszynski and Caron 1995; Premoli-Silva and Verga, 2004; Dimitrova and Valchev, 2007; Takashima et al., 2010). This zonation is similar to that of Robaszynski and Caron (1995). In this study, 54 species belonging to 15 genera of planktonic foraminifera, and 11 invertebrate species (8 inoceramids, 2 echinoids and 1 ammonite), were recognized in the Abderaz Formation (Fig. 8). The Padeha section has been correlated with other sections of the Abderaz Formation from West and East Kopet-Dagh Basin, which were previously studied by Shafiee Ardestani et al. (2012) (Fig. 9). These are the Hajgelichkhan section (Lowermost Turonian- Lowermost Santonian), Qarehso section (Lowermost Turonian-Late Santonian), Abderaz section (Early Turonian-Lowermost Campanian), Muzduran type section (Middle Turonian-Lowermost Campanian), and Shorab section (Lowermost Turonian-Lowermost Campanian) (Fig 9). Di. asymetrica Zone is of greater thickness than the others (Fig. 9). Rates of sedimentation in all studied sections are different. Planktonic foraminiferal biostratigraphy indicates early Turonian to earliest Campanian age of the Abderaz Formation. Five successive zones are described below.

Whiteinella archaeocretacea Partial-Range-Zone Bolli, 1966

Definition. Interval with Whiteinella archaeocretacea between the last occurrence data (LOD) of Rotalipora cushmani and the first occurrence data (FOD) of Helvetoglobotruncana helvetica. Planktonic foraminifera assemblage: Dicarinella cana liculata (Reuss, 1854), Di. hagni (Scheibnerova, 1962), Heterohelix globulosa (Ehrenberg, 1840), H. more mani (Cushman, 1938), H. reussi (Cushman, 1938), Macroglobigerinelloides bollii (Pessagno, 1967), M. ca seyi (Bolli, Loeblich and Tappan, 1957), M. ultramicra (Subbotina, 1949), Muricohedbergella delrioensis (Carsey, 1926), M. simplex (Morrow, 1934), Whiteinella aprica (Loeblich and Tappan, 1961), W. baltica Douglas and Rankin, 1969, W. brittonensis (Loeblich and Tappan, 1961), W. paradubia (Sigal, 1952), and W. praehelvetica (Trujillo, 1960). Remarks. The base of this zone coincides with the boundary between the Aitamir and the Abderaz Formation, Fig. 2. Lithological column of the Abderaz Formation at Padeha indicating an Early Turonian age for the lower part of section the Abderaz Formation. The planktonic foraminifers

23 Fig. 3. Planktonic foraminifera from the Upper Cretaceous of the studied section. Scale bar equals 100 μm 1 a, b, c. Costellagerina pilula, sample 76; 2 a, b, c. Costellagerina bulbosa, sample 82; 3 a, b, c. Marginotruncana pseudolinneiana, sample 185; 4. Marginotruncana sp, sample 185.

24 Fig. 4. Planktonic foraminifera from the Upper Cretaceous of the studied section. Scale bar equals 100 μm 1 a, b, c. Globotruncana linneiana, sample 175; 2 a, b, c. Globotruncana bulloides, sample 195; 3 a, b, c. Transition form between Archaeoglobigerina cretacea and A. blowi, sample 108; 4 a, b, c. Archaeoglobigerina cretacea, sample 85.

25 Fig. 5. Planktonic foraminifera from the Upper Cretaceous of the studied section. Scale bar equals 100 μm 1 a, b, c. Dicarinella asymetrica, sample 108; 2. Marginotruncana marginata, sample 91; 3. Muricohedbergella flandrini, sample 195; 4. Globotruncana linneiana, sample 200;

26 Fig. 6. Planktonic foraminifera from the Upper Cretaceous of the studied section. Scale bar equals 100 μm 1 a, b, c. Globotruncana arca, sample 190; 2 a, b, c. Transition form between Costellagerina bulbosa and C. pilula, sample 76; 3 a, b, c. Heterohelix striata, sample 37; 4 a, b, c. Heterohelix papula, sample 200.

27 Comparative table of the Upper Cretaceous foraminiferal zones proposed in this study and those Tethyan Realm Fig. 7.

28 adeha section Biostratigraphic range-chart of planktonic foraminifers and macrofossil invertebrates recorded from the Abderaz Formation at P Fig. 8.

29 st and East Kopet Dagh sedimentary basin Lithostratigraphic and biostratigraphic correlation of Padeha section with other sections the Abderaz Formation from We (Shafiee Ardestani et al., 2012, and this study) Fig. 9.

30 are poorly preserved. This zone consists of yellowish to Pessagno, 1967, M. renzi (Gandolfi, 1942), M. sigali gray marls 39 m thick (see Fig. 8). Inoceramus sp. and (Reichel, 1950), Muricohedbergella delrioensis (Carsey, Mytiloides sp. were also determined (Fig. 10). 1926), M. planispira (Tappan, 1940), Whiteinella ar- This zone was previously identified in the Lower chaeocretacea Pessagno, 1967, W. baltica Douglas and Turonian of the western Tethys (Wonders, 1980). Rankin, 1969, and W. paradubia (Sigal, 1952). According to Caron (1985) and Wonders (1980), the W. Remarks. This zone is 42 m thick (samples 47 to 61), archaeocretacea Zone is Early Turonian in age, but they and consists of light gray shales with yellowish to white suggested the FOD of W. archaeocretacea is uppermost chalky limestones (Figs 2, 8). Inoceramus sp., Mytiloides Cenomanian, too. However, Pessagno (1967) consid- sp., Cremnoceramus walterdorfensis walterdorfensis and ered this zone as corresponding to the Upper Turonian. Mytiloides herbichi were identified (Fig. 10). Postuma (1971) used Helvetoglobotruncana helvetica This interval is also known as the Middle to Upper as the index species in defining a Total-Range-Zone of Turonian Marginotruncana sigali-Dicarinella primitiva Turonian age. Sigal (1977) used the Rotalipora cush- Zone (Premoli Silva and Sliter, 1995). It was identified mani Total-Range-Zone for marking the Cenomanian- from the Upper Turonian to Lower Coniacian in the Turonian transition. In low latitudes, Premoli-Silva and Atlantic (McNulty, 1976; Premoli Silva and Sliter, 1981, Verga (2004) indicated that the W. archaeocretacea 1995), western Tethys (Wonders, 1980), central Tethys Zone is of Cenomanian-Turonian age, but Walaszczyk et (Fleury, 1980, Sigal, 1977), eastern Tethys (Gorbachik, al. (2004) considered this zone being of Turonian age in 1971a, b; Maslakova, 1971) and Pacific (Gradstein et the Bryansk Region. al., 1978; Pessagno and Longoria, 1973). Robaszynski Chronostratigraphy. Uppermost Cenomanian to Lower and Caron (1995) identified this biozone in the whole Turonian. Tethyan Realm. Chronostratigraphy Upper Turonian to Lower Coniacian. Helvetoglobotruncana helvetica Total-Range-Zone Sigal (1955) Dicarinella concavata Interval Zone Sigal, 1955 Definition. Interval of the total range of Helvetoglobo- truncana helvetica. Definition. The interval between the FOD of Dicari nella Planktonic foraminifera assemblage: Dicarinella al- concavata and the FOD of Dicarinella asymetrica. geriana (Caron, 1966), Di. hagni (Scheibnerova, 1962), Planktonic foraminifera assemblage: Archaeoglo- Di. imbricata (Monrod, 1950), Macroglobigerinelloides bigerina bosquensis Pessagno, 1967, A. cretacea (d’Or- ultramicra (Subbotina, 1949), Heterohelix globulosa bigny, 1840), Costellagerina pilula (Belford, 1960), (Ehrenberg, 1840), H. moremani (Cushman, 1938), C. bulbosa (Belford, 1960), Dicarinella canaliculata Muricohedbergella delrioensis (Carsey, 1926), M. plan- (Reuss, 1854), Di. hagni (Scheibnerova, 1962), Di. ispira (Tappan, 1940), Marginotruncana renzi (Gandolfi, primitiva (Dalbiez, 1955), Macroglobigerinelloides 1942), M. sinuosa Porthault, 1970, M. sigali (Reichel, caseyi (Bolli et al., 1957), Muricohedbergella delri- 1950), Whiteinella aprica (Loeblich and Tappan, 1961), oensis (Carsey, 1926), M. flandrini (Porthault, 1970), W. baltica Douglas and Rankin 1969, W. praehelvetica M. planispira (Tappan, 1940), M. simplex (Morrow, Trujillo, 1960, and W. paradubia (Sigal, 1952). 1934), Heterohelix globulosa (Ehrenberg, 1840), Mar- Remarks. This zone is 102 m thick (samples 13-47) and ginotruncana marginata (Reuss, 1845), M. paraconca- includes chalky limestones with shales intercalated (Figs vata Porthault, 1970, M. renzi (Gandolfi, 1942), M. si- 2, 8). Inoceramus sp. is frequent. The zone was previ- gali (Reichel, 1950), M. schneegansi (Sigal, 1952), M. ously identified from the Middle Turonian in the Atlantic sinuosa Porthault, 1970, Whiteinella archeocretacea (McNulty, 1976; Premoli-Silva and Sliter 1981), western Pessagno, 1967, W. baltica Douglas and Rankin, 1969, Tethys (Wonders, 1980), central Tethys (Fleury, 1980; W. brittonensis (Loeblich and Tappan, 1961), W. au- Sigal, 1977) and Pacific (Gradstein et al., 1978; Pessagno malensis (Sigal, 1952), and W. paradubia (Sigal, 1952). and Longoria, 1973). Keller et al. (2004) and Keller and Remarks. The thickness is about 78 m (samples 62 to Pardo (2004) considered that H. helvetica range is dia- 88), and the zone consists of shales, chalky limestones chronous in different localities. and light gray marls (Figs 2, 8) Chronostratigraphy. Lower and Middle Turonian. This zone was defined by Sigal (1955) who used FOD of Di. primitiva as the lower boundary indicator. Marginotruncana schneegansi FODs of Di. primitiva and Di. concavata have been Interval-Range-Zone Dalbiez (1955) documented almost at the same level in the Padeha section, thus we define the base of Di. concavata Zone at Definition. The interval between the FOD of Margino- the FOD of the index species. Sigal (1955) suggested truncana schneegansi and the FOD of Dicarinella a Late Coniacian to Early Santonian age for this zone, primitiva. but later it was dated as Coniacian to early Santonian Planktonic foraminifera assemblage: Archaeoglobige- by Premoli Silva and Verga (2004). Walaszczyk et al. rina bosquensis Pessagno, 1967, Dicarinella canaliculata (2012) documented that the FODs of Di. concavata (Reuss, 1854), Heterohelix globulosa (Ehrenberg, 1840), and Di. primiriva are coeval in the Upper Turonian Macroglobigerinelloides prairiehillensis (Pessagno, Mytiloides scupini inoceramid zone. 1967), M. caseyi (Bolli et al., 1957), Marginotruncana The zone was identified in the Coniacian to Lower paraconcavata Porthault, 1970, M. pseudolinneiana Santonian from the Atlantic Realm (McNulty, 1976;

31 32 ← Fig. 10. Inoceramids, echinoids and ammonites from the Upper Cretaceous of Abderaz section. Scale bar equals 5 cm 1, 2. Mytiloides sp. (Upper Turonian), samples 47, 53 ; 3. Cordiceramus sp. – Cordiceramus ex gr. mulleri (Santonian), sample 120; 4, 8. Cremnoceramus walterdorfensis walterdorfensis (Uppermost Turonian), sample 67; 5, 6. Echinocorys sp. (Lowermost Campanian), sample195; 7. Cremnoceramus sp (Coniacian), sample 53; 9. Mytiloides cf herbichi (Upper Turonian), sample 61; 10. Inoceramus cf.vistulensis (? Lower Coniacian), sample 85; 11. Cremnoceramus cf. deformis deformis (Lower Coniacian), sample 76; 12. Texanites hispanicus (Upper Santonian), sample 185.

Premoli-Silva and Sliter 1981), western Tethys (Wonders, placed within this zone. As far as Globotruncanita el- 1980), central Tethys (Fleury, 1980; Sigal, 1977) and the evata was not found, therefore we used the LOD of mar- Pacific Realm (Gradstein et al. 1978, 1994; Pessagno and ginotruncanids and the LOD of Ventilabrella austiniana Longoria, 1973). The following invertebrate macrofossils to distinguish the base of Campanian. The bulk of the have also been found: Inoceramus sp. (Upper Turonian), macrofossils identified from the Padeha section (Fig. 10) Mytiloides sp. (Upper Turonian), Cremnoceramus wal- came from this zone: Echinocorys ex gr. scutata (low- terdorfensis walterdorfensis (Andert, 1911) (Uppermost ermost Santonian), Platyceramus cf. ahsenensis (lower Turonian), Mytiloides herbichi (Atabekian, 1968) (Upper Santonian), Texanites hispanicus (Upper Santonian), and Turonian), Cremnoceramus cf. deformis deformis (Meek, Echinocorys sp. (lowermost Campanian). 1871), Inoceramus cf. vistulensis (Walaszczyk, 1992), Chronostratigraphy. Lower Santonian – lowermost and Echinocorys gr. scutata (base of Santonian). Campanian Chronostratigraphy. Uppermost Turonian, Cenomanian and Lowermost Santonian. INTEGRATED FORAMINIFERAL Dicarinella asymetrica AND INOCERAMID BIOSTRATIGRAPHY Total Range Zone Postuma, 1971 Base of Coniacian Definition. Total range zone of Dicarinella asymetrica. Planktonic foraminifera assemblage: Archaeoglobi- Caron (1979), Robaszynski and Caron (1979), Birkelund gerina bosquensis Pessagno, 1967, A. cretacea (d’Or- et al. (1984), and Marks and Stan (1983) considered bigny, 1840), Contusotruncana fornicata (Plummer, that the FOD of Dicarinella primitiva is located at the 1931), C. pateliformis (Gandolfi, 1955), Dicarinella ca- basal part of the Coniacian. However, this biohorizon naliculata (Reuss, 1854), Di. concavata (Brotzen, 1934), was later placed at the Turonian/Coniacian bound- Di. hagni (Scheibnerova, 1962), Globotruncana arca ary (Robaszynski et al., 1990; Robaszynski and Caron, (Cushman, 1926), G. bulloides Vogler, 1941, G. linneia- 1995). The latter authors indicated that the FODs of Di. na (d’Orbigny, 1839), Heterohelix globulosa (Ehrenberg, primitiva and Di. concavata coincide in the late Turonian 1840), H. papula (Belford, 1960), Laeviheterohelix pul- and are well-correlated with the FOD of the ammonite chra (Brotzen, 1936), Macroglobigerinelloides alvarezi Subprionocyclus neptuni. This event was recorded close (Eternod Olvera, 1959), M. bollii (Pessagno, 1967), M. to the Middle-Upper Turonian transition (Robaszynski et escheri Kaufmann, 1865, M. prairiehillensis (Pessagno, al. 1990; Robaszynski and Caron, 1995). Gebhardt (2001) 1967), M. sp., Marginotruncana coronata (Bolli, 1945), considered the FOD of the ammonite Prionocycloceras M. marginata (Reuss, 1845), M. pseudolinneiana Pessag- milticostatum as indicative for the Turonian/Coniacian no, 1967, M. paraconcavata Porthault, 1970, M. ren- boundary. zi (Gandolfi, 1942), M. schneegnasi (Sigal, 1952), M. Although most planktonic foraminiferal special- sigali (Reichel, 1950), M. sinuosa Porthault, 1970, ists considered the Turonian/Coniacian boundary as not M. tarfayensis (Lehmann, 1963), Muricohedbergella traceable precisely upon planktonic foraminifera, others flandrini (Porthault, 1970), M. holmdelensis (Olsson, suggested that the FOD of Marginotruncana sinuosa 1964), M. planispira (Tappan, 1940), M. simplex can be used to define the base of Coniacian (Birkelund (Morrow, 1934), Pseudotextularia nuttalli (Voorwijk, et al. 1984; Marks and Stan, 1983; Kauffman et al., 1937), Pseudoguembelina costellifera Masters, 1976, 1996, Walaszczyk et al., 2010). Gebhardt (2001 a, b) Rugoglobigerina pennyi Brönnimann, 1952, R. rugo- used Muricohedbergella flandrini to recognize the Late sa (Plummer, 1926), Ventillabrella austiana Cushman, Turonian. The LODs of Muricohedbergella simplex and 1938, Whiteinella aumalensis (Sigal, 1952), and W. ar- Dicarinella primitiva precede the FOD of Dicarinella chaeocretacea Pessagno, 1967. concavata (Koutsoukos and Bengtson, 1993). Remarks. This biozone is 333 m thick (samples 89 to The FOD of Cremnoceramus deformis erectus (Meek, 200) (Fig. 8). The Santonian/Campanian boundary is 1811) was used to place the base of Coniacian (Wood et

33 Fig. 11. Correlation of inoceramid zonations

al., 1984, 2004; Kauffman et al., 1996; Walaszczyk and FOD of C. pilula to be lower than the FOD of C. de- Wood, 1999, 2000, 2008; Walaszczyk and Coban 2000; formis deformis. Therefore, Marginotruncana paracon- Ogg et al., 2004; Walaszczyk et al., 2010, 2012) (Fig. 11). cavata and Costellagerina pilula are latest Turonian in The FOD of Cremnoceramus rotundatus (sensu Troger) age, thus representing reliable indicators for recognizing (= Cremnoceramus deformis erectus), was recommend- the Turonian/Coniacian boundary in Iran. ed for defining the Turonian/Coniacian boundary by the Coniacian Working Group (CWG) of the Cretaceous Base of Santonian Subcomission on Stratigraphy (Kauffman et al., 1996; Walaszczyk et al., 2010). In the studied area, C. deformis Caron (1985) and Robaszynski and Caron (1979) reported erectus has not been found, but the FODs of Di. primi- Dicarinella concavata from the Late Coniacian to Early tiva and Di. concavata have been recognized below the Santonian, whereas other authors (Wonders 1980; Van FOD of Cremnoceramus deformis deformis in the Early Hinte, 1976; Sigal, 1977; Postuma, 1971; Pessango, Coniacian, thus confirming the foraminiferal FODs latest 1967; Bolli, 1966) considered the Di. concavata Zone as Turonian age. Lamolda and Paul (2007) used the FOD corresponding to the Coniacian only. Consequently, the of Costellagerina pilula as the main key planktonic fo- Turonian/Coniacian and Coniacian/Santonian boundaries raminiferal horizon for the Coniacian/Santonian bound- have been placed within the D. concavata Zone of large ary in Spain. However, the present study recorded the stratigraphic volume in the studied area. The FOD of the

34 inoceramid Cladoceramus undulatoplicatus (Roemer) Dicarinella asymetrica (Postuma) Total Range Zone. was used as a global marker of the Coniacian/Santonian These zones were correlated with previously docu- boundary (Gallemí et al., 2007a, b; Hampton et al., 2007; mented occurrences in four sections in West and East Ion et al., 1994; Kopaevich et al., 2007; Lamolda and Kopet-Dagh Basin: Hajgelichkhan, Qarehso, Abderaz, Hancock, 1996; Lamolda and Paul, 2007; Melinte et Muzduran, and Shorab, (Shafiee Ardestani et al., 2012). al., 2007; Peryt and Lamolda, 2002, 2007). We have not Biostratigraphic data indicate that the Abderaz recognized Cladoceramus undulatoplicatus. For this reason Formation of Padeha section is continuous and allows we have used the FOD of the echinoid Echinocurys ex gr. the recognition of three stage boundaries of the Upper scutata as a secondary marker of the base of Santonian as Cretaceous: the Turonian/Coniacian, Coniacian/Santonian proposed by Gallemí et al. (2007a, b). Using the FOD of and Santonian/Campanian. Parallel to the biostratigraphy E. ex gr. scutata, the Coniacian/Santonian boundary has of the planktonic foraminifers, the stratigraphic distribu- been placed at the position of the sample 85 in the Padeha tion of several macrofossil taxa has also been identified: section. The FOD of Dicarinella asymetrica has been eight inoceramid species, 2 echinoids and 1 ammonite. documented in sample 88, i.e. 9 m above the Coniacian/ The FOD of the inoceramid Cremnoceramus walterdor- Santonian boundary (Fig. 8). It is evident, therefore, that fensis walterdorfensis has been used to recognize the the FOD of Di. asymetrica is not a reliable horizon to place uppermost Turonian, and the FOD of Cremnoceramus the Coniacian/Santonian boundary in the studied section deformis deformis to identify the middle part of Lower (Figs 1a–c and 5). Coniacian in the Abderaz Formation. The base of the Santonian has also been recognized using the FOD of the echinoid Echinocorys ex gr. scutata. Finally, the LOD of CONCLUSIONS the foramininfers of the Marginotruncanid group in addi- tion to the LOD of Ventilabrella austiniana were used to Planktonic foraminiferal biostratigraphic study of the identify the base of Campanian. Abderaz Formation in the Padeha section has been based on distribution of 54 species belonging to 15 genera. Five Acknowledgments successive foraminiferal zones have been recognized, from the lower Turonian to the lowermost Campanian. In This research was funded by Ferdowsi University ascending order these are: of Mashhad, the Spanish Ministerio de Ciencia e Whiteinella archaeocretacea (Bolli) Partial Range Innovación project CGL2011-22912, co-financed by the Zone; ERDF (European Regional Development Fund), and the Helvetoglobotruncana helvetica (Sigal) Total Range Aragonian Departamento de Educación y Ciencia (DGA Zone; group E05). The authors would like to express their deep Marginotruncana schneegansi (Dalbiez) Interval gratitude to Prof. Robaszynski for his invaluable help Range Zone; during the study. The paper is proudly dedicated to the Dicarinella concavata (Sigal) Interval Range Zone; living memory of Prof. Hesabi.

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