02 - Hernitz-Kucenjak et al.indd 1. INTRODUCTION In different geological periods, planktonic foraminifera were deposited over an extensive portion of the world oceans and seas, and are often found in large numbers. Industrial application of planktonic foraminiferal bios- tratigraphic studies began in the middle of the last cen- tury in the Gulf Coast region of the USA and quickly spread through the principal oil-producing parts of the world (STAINFORTH et al., 1975; BOERSMA, 1988). This has resulted in the recognition of their usefulness for both local and regional biostratigraphic zonation and correlation (BOLLI & SAUNDERS, 1985; BERG- GREN et al., 1995). Numerous biostratigraphic studies of planktonic foraminifera have originated from the Former Soviet Union – the first zonal scheme for planktonic foraminif- Planktonic Foraminiferal Biostratigraphy of the Late Eocene and Oligocene in the Palmyride Area, Syria Morana HERNITZ KUČENJAK, Vlasta PREMEC FUĆEK, Renata SLAVKOVIĆ and Ivan A. MESIĆ era was published by SUBBOTINA (1947) for sec- tions of the Caucasus Mountains. Afterwards, a large number of planktonic foraminiferal studies were pub- lished, e.g. BOLLI (1957), BLOW (1979), TOU- MARKINE & LUTERBACHER (1985), BERGGREN & MILLER (1988), and others. A revised geochronol- ogy and geochronostratigraphic study was published by BERGGREN et al. (1995). Further investigations of the planktonic foraminiferal ranges from different parts of the world have provided knowledge for a new zonation (BERGGREN & PEARSON, 2005; PEARSON et al., 2006). Important biostratigraphical work on the Palaeo- gene deposits in Syria has been undertaken by KRASH- ENINNIKOV et al. (1996). A previous biostratigraph- ic investigation in the Palmyride area, on material from deep exploration wells was done by HERNITZ KUČENJAK et al. (2005). In the present work, a planktonic foraminiferal fauna from three deep exploration wells Jihar–1, Jihar–4 and Jihar–5 drilled in the Palmyride area (Fig. 1) has been examined. A rich, highly to moderately diverse and well preserved planktonic foraminiferal association enabled biostratigraphical zonation of the late Eocene and Oli- gocene deposits (Fig. 3). On the basis of the composi- tion of the foraminiferal assemblages, diversity, changes of test morphology and wall texture, palaeoecological and palaeoclimatic interpretations have been made. 2. MATERIAL AND METHODS The detailed biostratigraphic study was based on material from drill cuttings from three deep explora- tion wells (Jihar–1, Jihar–4 and Jihar–5) drilled in the Hayan exploration block in the Palmyride area (Fig. 1). Samples for micropalaeontological analyses were taken at every 10 m in Jihar–1 and Jihar–5 wells and at 20 m intervals in the Jihar–4 well. Samples were soaked in water with a small amount of hydrogen per- oxide and then washed under running water through 63 µm, 125 µm, 160 µm and 630 µm sieves. These four fractions were dried in a drier and from each fraction foraminifera were picked out onto micropalaeontologi- cal slides. Microfossil associations were examined on a stereo microscope, whereas a detailed study of the Geologia Croatica 59/1 19–39 3 Figs. 5 Pls. ZAGREB 2006 Key words: Biostratigraphy, Planktonic foraminifera, Late Eocene, Oligocene, Palmyride area, Syria. INA – Industrija nafte d.d., Research and Development Sector, Rock and Fluid Research Lab. Dept., Lovinčićeva bb., 10000 Zagreb, Croatia; e-mail: morana.hernitz-kucenjak@ina.hr Abstract Three deep exploration wells in the Palmyride area (Syria) have been drilled through Oligocene and Eocene deposits. A detailed micro- palaeontological investigation has been performed on the planktonic foraminiferal assemblage from drill cuttings. Standard planktonic foraminiferal zones from P15 to P22 (E15 to O6) have been identi- fied. The test morphology and diversity of the foraminiferal assem- blage indicate a general cooling trend during the late Eocene and Oligocene. The specialized Eocene forms (K-mode life strategy) such as turborotaliids, globigerinathekids and hantkeninids become extinct in the uppermost late Eocene. The Oligocene is characterized by the dominance of cooler, opportunistic planktonic foraminifera (r-mode life strategy), such as pseudohastigerinids, chiloguembelinids, glo- bigerinids and tenuitellids. A very low number of benthic foraminif- era in late Eocene cuttings implies sedimentation in a deep, open sea environment. A gradual increase of the benthic foraminiferal propor- tion through the Oligocene indicates shallowing of the sedimentary environment. 20 Geologia Croatica 59/1 planktonic foraminiferal morphology was performed on scanning electron microscope (SEM). Biostratigraphic interpretation was based on the standard planktonic foraminiferal biozonation (P zones) – BERGGREN et al. (1995), and new planktonic foraminiferal biozonation (E and O zones) – BERG- GREN & PEARSON (2005) and PEARSON et al. (2006) (Fig. 2). Determination of the planktonic foraminiferal gen- era and species was based on BOLLI & SAUNDERS (1985), TOUMARKINE & LUTERBACHER (1985), SPEZZAFERRI (1994), IACCARINO et al. (2005) and PREMOLI SILVA & PETRIZZO (2006). The classifi- cation scheme used follows LOEBLICH & TAPPAN (1988). Here, determination of planktonic foraminiferal biozones was based on the last occurrence (LO) of the index taxa to avoid possible mistakes as a result of mix- ing different foraminiferal associations in drill cuttings. The only exception is the boundary between zones O3 (P20) and O4 (P21a) which is defined by the first occur- rence (FO) of Globigerina angulisuturalis. Because of the difficulty in identification of the first occurrence of the zonal marker, this boundary is an approximation. 3. GEOLOGICAL SETTING The foraminiferal fauna has been studied from the Hayan exploration block (Fig. 1), which is situated in the Palmyride area (Central part of Syria). The Palmyrides are an inverted Mesozoic rift basin (LUČIĆ & FORŠEK, 2000; BREW, 2001; BREW et al., 2001). Inversion began in the Late Cretaceous, but the major- ity of the inversion took place in the Miocene (BREW, 2001). Syria can be divided into four major tectonic zones: the Palmyride area, the Abd el Aziz–Sinjar area, the Euphrates Fault System, and the Dead Sea Fault System (BREW, 2001; BREW et al., 2001). The Palmyrides are an intracontinental mountain fold belt which extend Fig. 1 Map of Syria showing the location of the main tectonic zones (modified from BREW, 2001). A circle represents the approximate loca- tion of the Hayan exploration block. 21Hernitz Kučenjak et al.: Planktonic Foraminiferal Biostratigraphy of the Late Eocene and Oligocene... from the Dead Sea Fault Zone in the west, and join the Euphrates fault system in the east (LUČIĆ & FORŠEK, 2000; BREW, 2001). The Palmyrides extend 400 km approximately southwest to northeast across Syria, and they are 100 km wide (LUČIĆ & FORŠEK, 2000; BREW, 2001). They can be further divided on the basis of topography and structure into the southwestern Palmyrides (a fold and thrust belt) and the northeastern Palmyrides – the Bilas and Bishri blocks. The Jihar fault separates the two areas (BREW, 2001). Between the Jihar fault and the short-wavelength folds of the south- ern Palmyrides lies the low-relief Al Daww Depression (LUČIĆ & FORŠEK, 2000; BREW, 2001), which is a 100 km long and 20 km wide inter-montaine basin. The Hayan block is situated partly in the Al Daww depres- sion and extends towards the Bilas block. In the geological evolution of Syria during the Palaeogene, five main steps have been observed by KRASHENINNIKOV et al. (1996), which correspond to the following lithostratigraphic formations: cal- PLANKTONIC FORAMINIFERAL ZONES Berggren et al. (1995) Berggren & Pearson (2005) This workE P O C H M IO C E N E O LI G O C E N E LA TE LA TE E A R LY C H AT IA N R U P E LI A N P R IA B O N IA N E O C E N E E A R LY A Q U IT - A N IA N A G E M1b M1a P22 O6 O6 O5 O5 O4 O4 O3 O3 O2 O2 O1 O1 E16 E16 E15 E15 E14 E14 b a P 21 P20 P19 P18 P15 P16 Gt. kugleri / Gq. dehiscens Gd. primordius PRZ Gl. ciperoensis PRZ Gl. angulisuturalis / Pg. opima s.s. ISZ Gl. angulisuturalis / Ch. cubensis CRSZ Ch. cubensis - Pseudohastigerina spp. IZ T. cerroazulensis IZ T. cunialensis / Cr. inflata CRZ Gl. angulisuturalis / Ch. cubensis CRZ Gl. angulisuturalis / Ch. cubensis Pg. opima HOZ Gl. sellii PRZ T. ampliapertura IZ T. ampliapertura HOZ P. naguewichiensis HOZ H. alabamensis HOZ Po. semiinvoluta IZ G. semiinvoluta HOZ G. semiinvoluta H. alabamensis G. index HOZ G. index P. naguewichiensis T. ampliapertura Gl. selliiGl. sellii PRZ Pg. opima Gl. ciperoensis PRZ Gl. ciperoensis not studied not studiedCRZ P17 Fig. 2 Biostratigraphical zonation based on the planktonic foraminifera (after BERGGREN & PEARSON, 2005); abbreviations: IZ – Interval Zone, CRZ – Concurrent-range Zone, PRZ – Partial-range Zone, CRSZ – Concurrent-range Subzone, ISZ – Interval Subzone, HOZ – Highest-occurrence Zone. 22 Geologia Croatica 59/1 careous clays and marls in the Palaeocene and Lower Eocene; alternation of limestones and flints in the uppermost Lower Eocene; chalky and nummulitic lime- stones in the Middle Eocene; alternation of chalky and hard fine-grained limestones in the Upper Eocene and finally shallow biogenic limestones with terrigenous sediments at the top of the Palaeogene formations, deposited during the Oligocene. In the Palmyrides, the Oligocene marine sedimenta- tion stopped at the Neogene boundary, and the marine Palaeogene is overlain by continental sediments or by unconformable and transgressive marine Lower Miocene deposits. 4. LITHOLOGY In the studied exploration area, the Middle Eocene argil- laceous limestones underlie the Upper Eocene depos- its. These argillaceous limestones are greyish white to grey–greenish wackestone/packstones. They occasion- ally grade into calcareous marl, grey to brownish in colour. In places there are a few occurrences of grey quartz arenites. The Upper Eocene sedimentary rocks (biozones E14 to E16) are represented by greyish–white to grey–greenish argillaceous limestones of wackestone to wackestone/packstone types. Occasional occurrences of marls have been found, but only in the Jihar–4 well. The Lower Oligocene sediments are composed of light grey to grey marls, and white to grey–greenish argil- laceous limestones of wackestone/packstone types. Deposits of the Upper Oligocene consist of grey, spo- radically sandy–clayey marls, with occurrences of very light grey fine- to medium-grained quartz arenites. The Upper Oligocene deposits are overlain by the light grey sandstones of quartz wacke to quartz arenite type, and grey to brownish grey marls, possibly Early Miocene in age. According to the lithological characteristics of dep- osits and composition of the foraminiferal associa- tion (plankton/benthos ratio approx. 70:30), the Upper Eocene rocks were probably deposited in the open shelf environment, whereas the Oligocene deposits (plank- ton/benthos ratio approx. 40:60) were accumulated in the outer to middle shelf environment. 5. PLANKTONIC FORAMINIFERAL BIOZONATION OF THE LATE EOCENE TO OLIGOCENE The frequency of planktonic foraminifera in the samples enables application of standard planktonic foraminiferal zonations (BERGGREN et al., 1995; BERGGREN & PEARSON, 2005; PEARSON et al., 2006 – Fig. 2). Zones E14 (P15) and E15/E16 (P16/P17) have been identified in the Upper Eocene. Zones from O1 (P18) to O6 (P22) have been recognized in the Oligocene sedi- mentary succession (Fig. 3). Zone E14 Globigerinatheka semiinvoluta – BERGGREN & PEARSON, 2005; PEARSON et al., 2006 (approx. = Ponticulasphaera semiinvoluta Zone P15 – BERGGREN et al., 1995) Intervals: Jihar–1 (approx. 460 to 500 m), Jihar–4 (approx. 635 to 675 m), Jihar–5 (approx. 310 to 350 m). In the material studied, a very well preserved plank- tonic foraminiferal association has been presented. The lower boundary of this Zone is defined by the extinc- tion of all morozovellids and large acarininids and cor- responds very well with previous investigations in the Mediterranean and Atlantic areas (PREMOLI SILVA & BOERSMA, 1988; PREMEC-FUĆEK et al., 1998; WADE, 2004). Only very small muricate species, such as Acarini- na medizzai TOUMARKINE & BOLLI and Acarinina collactea (FINLAY), persisted across the Middle/Late Eocene boundary as in other Mediterranean bioprov- inces (PREMOLI SILVA & BOERSMA, 1988; PRE- MEC-FUĆEK et al., 1998). In the investigated wells, A. medizzai (Pl. 1, Figs. 1–4) and A.collactea became extinct at the end of Zone E14. In that interval, the Turborotalia lineage was represented by Turborotalia cerroazulensis (HOWE & WALLACE), T. pomeroli (TOUMARKINE & BOLLI), T. cocoaensis (CUSH- MAN), and transitional forms between T. pomeroli and T. cerroazulensis (Pl. 1, Fig. 6). The microperforate species Pseudohastigerina micra (COLE) (Pl. 1, Fig. 5) was very frequent in the foraminiferal association of zone E14. Furthermore, Subbotina cryptomphala (GLAESNER), S. eocaena (GUEMBEL), S. angiporo- ides (HORNIBROOK), S. yeguaensis (WEINZIERL & APPLIN), Globigerinatheka luterbacheri BOLLI, G. index (FINLAY), and Hantkenina alabamensis CUS- HMAN (Pl. 1, Figs. 8 & 9) have been identified. As the zone marker, Globigerinatheka semiinvoluta (KEI- JZER), in the analysed samples has not been presented, the top of Zone E14 is defined approximately by the last occurrence of the Acarinina medizzai (PREMOLI SILVA & PETRIZZO, 2006; PEARSON et al., 2006). Zone E15 Globigerinatheka index – BERGGREN & PEARSON, 2005; (approx. upper part of Ponticulasphaera semiinvoluta Zone P15 and lower part of Turborotalia cunialensis/ Cribrohantkenina inflata Zone P16 – BERGGREN et al., 1995) and Zone E16 Hantkenina alabamensis – BERGGREN & PEARSON, 2005 (approx. upper part of Turborotalia cunialensis/ Cribrohantkenina inflata Zone P16 and Globigerina gortanii gortanii – Turborotalia centralis P17 – BERGGREN et al., 1995) Intervals: Jihar–1 (410 to approx. 460m), Jihar–4 (595 to approx. 635 m), Jihar–5 (270 to approx. 310 m). Separation of Zones E15 and E16 has not been possible because the index taxon Globigerinatheka index (FIN- LAY) has only been found in the Jihar–1 well. 23Hernitz Kučenjak et al.: Planktonic Foraminiferal Biostratigraphy of the Late Eocene and Oligocene... JI H A R -1 JI H A R -4 JI H A R -5 10 0 20 0 30 0 40 0 60 0 50 0 O 6 94 97 m 31 67 m O 5 O 4 O 3 O 2 O 1 E 15 /1 6 E 14 LI M E S TO N E A R G IL LA C E O U S M A R L C LA Y E Y M A R L S A N D Y C LA Y E Y M A R L LE G E N DSW N E SE N W Large acarininids and morozovellids Acarinina medizzai Turborotalia cerroazulensis group Turborotalia ampliapertura Turborotalia ampliapertura Globigerina angulisuturalis Chiloguembelina cubensis Paragloborotalia opima Streptochilus pristinum Globigerinoides primordius Paragloborotalia opima Cribrohantkenina inflata Hantkenina alabamensis Pseudohastigerina naguewichiensis FI R S T O C C U R E N C E LA S T O C C U R E N C E P R E S U M E D B O U N D A R Y 0 m Fig. 3 Schematic profile of the exploration wells with planktonic foraminiferal bio- zones and last occurrence (LO) and approx. first occurrence (FO) of index taxa. 24 Geologia Croatica 59/1 The planktonic foraminiferal assemblage of these intervals consists of a few representatives of the Tur- borotalia lineage which do not extend beyond the Eocene/Oligocene boundary – Turborotalia cerroa- zulensis (HOWE & WALLACE) (Pl. 2, Figs. 4–6), T. pomeroli (Pl. 2, Figs. 8 & 9), and T. cocoaensis (CUSH- MAN) (Pl. 2, Figs. 1–3), whereas species including T. increbescens (BANDY) and T. ampliapertura (BOLLI) persist into the Early Oligocene. Cribrohantkenina inflata (HOWE) (Pl. 2, Fig. 7), is a species with a very short stratigraphic range, from the upper part of Zone E14 to the end of E16 (PEARSON et al., 2006), and has only been observed in the Jihar–5 well. Small microp- erforate species Pseudohastigerina micra (COLE), P. naguewichiensis (MYATLIUK), biserial Chiloguembe- lina cubensis (PALMER) and tenuiteliids in the 63–125 µm size fraction have also been observed. In the late Eocene assemblage, the coexistence of Subbotina cry- ptomphala (GLAESNER), S. yeguaensis (WEINZI- ERL & APPLIN), S. linaperta (FINLAY), S. corpulenta (SUBBOTINA) (Pl. 1, Fig. 7), Catapsydrax dissimilis (CUSHMAN & BERMUDEZ), C. unicavus BOLLI (Pl. 1, Fig. 10), Globigerina officinalis SUBBOTINA, Globigerinatheka luterbacheri, BOLLI and Dentoglo- bigerina galavisi (BERMUDEZ) (Pl. 1, Figs. 11 & 12) have been observed. Zone O1 Pseudohastigerina naguewichiensis – BERGGREN & PEARSON, 2005 (approx. Chiloguembelina cubensis – Pseudohastigerina sp. P18 – BERGGREN et al., 1995) Intervals: Jihar–1 (390–410 m), Jihar–4 (555–595 m), Jihar–5 (220–270 m). The Eocene/Oligocene boundary is marked by the fau- nal overturn which is indicated by the extinction of spe- cialized forms, such as the Turborotalia cerroazulensis s.s. group, globigerinathekids and hantkeninids (KEL- LER, 1983; BOERSMA & PREMOLI SILVA, 1991). In the earliest Rupelian, the planktonic foraminiferal assemblage comprises mostly round-chambered forms such as high and low spired subbotinids, catapsydrac- ids, dentoglobigerinids, microperforate tenuitellids, pseudohastigerinids and chiloguembelinids (IACCA- RINO et al., 2005). The assemblage of this zone in the investigated wells is characterized by the occurrence of globigerinids and dentoglobigerinids such as “Glo- bigerina” rohri (BOLLI) (Pl. 3, Fig. 7), “Globigerina” venezuelana HEDBERG, “Globigerina” euapertura JENKINS, Dentoglobigerina globularis (BERMUDEZ) (Pl. 3, Fig. 4) and D. baroemoensis (LE ROY) (Pl. 3, Figs. 5 & 6). Turborotalia increbescens (BANDY) (Pl. 2, Figs. 11 & 12) and T. ampliapertura (BOLLI) (Pl. 2, Fig. 10) are the representatives of the Turborotalia lin- eage persisting across the Eocene/Oligocene boundary. Small microperforate species in the samples of this zone are Pseudohastigerina naguewichiensis (MYATLIUK) (Pl. 3, Figs. 2 & 3), Chiloguembelina cubensis (PALM- ER) and tenuitelids. Species which range from the Mid- dle Eocene, Paragloborotalia nana (BOLLI) (Pl. 3, Fig. 1) are also represented. The top of Zone O1 is marked by the extinction of Pseudohastigerina naguewichiensis (BERGGREN & PEARSON, 2005). In the investiga- ted wells the last occurrence of P. naguewichiensis has been observed in the following samples: Jihar–1 – 390– 400 m, Jihar–4 – 555–575 m, Jihar–5 – 220–230 m. Zone O2 Turborotalia ampliapertura – BERGGREN & PEARSON, 2005 (“Turborotalia ampliapertura” P19 – BERGGREN et al., 1995) Intervals: Jihar–1 (360–390 m), Jihar–4 (515–555 m), Jihar–5 (210–220 m). The base of Zone O2 is defined by the last appearance datum of Pseudohastigerina naguewichiensis. The planktonic foraminiferal association from Zone O2 con- sists of large forms such as “Globigerina” tapurien- sis BLOW & BANNER, “Globigerina” venezuelana HEDBERG, Catapsydrax martini (BLOW & BAN- NER), “Globigerina” sp. and Dentoglobigerina sp. (Pl. 3, Figs. 11 & 12). Representatives of the microperforate planktonic foraminifera are still present – Cassigerinella chipolensis (CUSHMAN & PONTON), Chiloguembe- lina cubensis (PALMER) and Tenuitellinata sp. Moreo- ver, in samples from the Palmyra region Turborotalia ampliapertura (BOLLI) (Pl. 3, Figs. 8 & 9), Turboro- talia increbescens (BANDY) (Pl. 3, Fig. 10), Globotur- borotalita ouachitaensis (HOWE & WALLACE) and Globigerina praebulloides BLOW have been observed. The top of Zone O2 is defined by the last appearance datum of Turborotalia ampliapertura (BERGGREN et al., 1995; BERGGREN & PEARSON, 2005). In the Jihar–1 well the last occurrence of T. ampliapertura is in the 360–370 m sample, in Jihar–4 at 515–535 m, and in Jihar–5 at the 210–220 m samples. Zone O3 Globigerina sellii – BERGGREN & PEARSON, 2005 (Globigerina sellii P20 – BERGGREN et al., 1995) Intervals: Jihar–1 (approx. 320–360 m), Jihar–4 (app- rox. 495–515 m), Jihar–5 (approx. 200–210 m). The material of this Zone is characterised by the fre- quent occurrence of small microperforate planktonic foraminifera Chiloguembelina cubensis (PALMER), Cassigerinella chipolensis (CUSHMAN & PONTON), Tenuitellinata angustiumbilicata (BOLLI) (Pl. 4, Figs. 2 & 3) and Tenuitella gemma (JENKINS) (Pl. 4, Fig. 6). Further, in the planktonic foraminiferal association, larger forms such as “Globigerina” tripartita KOCH (Pl. 4, Fig. 4), “Globigerina” venezuelana HEDBERG (Pl. 4, Fig. 5), “Globigerina” sp., Globorotaloides sp. (Pl. 4, Fig. 1), Dentoglobigerina sp. and Paragloboro- talia opima (BOLLI) are determined. Also small glo- bigerinids, Globigerina praebulloides BLOW and Glo- bigerina praebulloides occlusa BLOW & BANNER, are represented. 25Hernitz Kučenjak et al.: Planktonic Foraminiferal Biostratigraphy of the Late Eocene and Oligocene... Due to difficulties in identifying the first appearance datum of the index species in the material from drill cuttings, the top of the zone is established approximate- ly by the first occurrence of Globigerina angulisutura- lis (BERGGREN et al., 1995; BERGGREN & PEAR- SON, 2005). First occurrence of G. angulisuturalis in the investigated Syrian wells has been recognized in the following samples: Jihar–1 – 200–210 m, Jihar–4 – 495–515 m and Jihar–5 – 320–330 m. Zone O4 Globigerina angulisuturalis/ Chiloguembelina cubensis – BERGGREN & PEARSON, 2005 (Globigerina angulisuturalis/ Chiloguembelina cubensis P21a – BERGGREN et al., 1995) Intervals: Jihar–1 (280 to approx. 320 m), Jihar–4 (475 to approx. 495 m), Jihar–5 (190 to approx. 200 m). The planktonic foraminiferal association of this zone is very well preserved and diverse. Small globigerinids Globigerina angulisuturalis (BOLLI) (Pl. 4, Figs. 7–9), G. ciperoensis (BOLLI), G. ouachitaensis (HOWE & WALLACE) and G. praebulloides BLOW are very fre- quent in Zone O4 samples. Microperforate species Chi- loguembelina cubensis (PALMER) (Pl. 4, Figs. 11 & 12), Cassigerinella chipolensis (CUSHMAN & PON- TON), and Tenuitella gemma (JENKINS) are also docu- mented from this interval, as well as larger forms Cata- psydrax martini (BLOW & BANNER), “Globigerina” tapuriensis BLOW & BANNER, “Globigerina” ven- ezuelana HEDBERG (Pl. 4, Fig. 10), Paragloborotalia opima (BOLLI), Dentoglobigerina sp. and Globorota- loides sp. The top of Zone O4 is marked by extinction of the microperforate biserial planktonic foraminifera Chiloguembelina cubensis (BERGGREN et al., 1995; BERGGREN & PEARSON, 2005). In the Jihar–1 well the LO of C. cubensis has been noticed in a sample at 280–290 m, in Jihar–4 at 475–495 m and in Jihar–5 at 190–200 m sample. Zone O5 Paragloborotalia opima – BERGGREN & PEARSON, 2005 (Globigerina angulisuturalis/ Paragloborotalia opima opima P21b – BERGGREN et al., 1995) Intervals: Jihar–1 (250–280 m), Jihar–4 (435–475 m), Jihar–5 (170–190 m). The planktonic foraminiferal association in the lower Chatian consists of small spinose globigerinids Globi- gerina angulisuturalis (BOLLI), Globigerina cipero- ensis (BOLLI) (Pl. 5, Fig. 1), G. officinalis SUBBOTI- NA and G. praebullides BLOW. In addition, Paraglo- borotalia opima (BOLLI) (Pl. 5, Figs. 5 & 6), P. nana (BOLLI) (Pl. 5, Figs. 8 & 9), and “Globigerina” sp. are also determined. Microperforate species Cassigerinella chipolensis (CUSHMAN & PONTON) (Pl. 5, Figs. 2 & 3), Tenuitellinata angustiumbilicata (BOLLI), and Tenuitellinata sp. in the 63 µm sieve fraction have been observed. The top of Zone O5 is marked by the last occurrence of Paragloborotalia opima, which has been recognized at 250–260 m in Jihar–1, at 435–455 m in Jihar–4 and at 170–180 m in Jihar–5. Zone O6 Globigerina ciperoensis – BERGGREN & PEARSON, 2005 (Globigerina ciperoensis P22 – BERGGREN et al., 1995) Intervals: Jihar–1 (approx. 220–250 m), Jihar–4 (app- rox. 415–435 m), Jihar–5 (approx. 160–170 m). The assemblage of this Zone is characterised by the occurrence of Globigerina angulisuturalis (BOLLI) (Pl. 5, Figs. 11 & 12), G. ciperoensis (BOLLI) (Pl. 5, Figs. 4 & 7), G. praebulloides BLOW, Dentoglobigeri- na baroemoensis (LE ROY), and Globigerina sp. In the Jihar–5 well, a very rare microperforate biserial species Streptohilus pristinum BROENNIMANN & RESIG (Pl. 5, Fig. 10) has been found. Furthermore, microperforate Tenuitellinata angustiumbilicata (BOLLI) and Tenui- tella sp. have also been determined. In this zone, the first appearance of Globigerinoides primordius BLOW & BANNER was observed. The boundary between the Oligocene and Miocene is marked by the first occur- rence of Globorotalia kugleri s.s. (BERGGREN et al., 1995; BERGGREN & PEARSON, 2005). This plank- tonic foraminiferal species has not been found in sam- ples from exploration wells, and the boundary of this zone is only approximately established. The following facts aided the establishment of the Eocene/Oligocene boundary: first, changes were evident in the foraminif- eral association, i.e. an increased abundance of benthic foraminifera (Neoeponides schreibersi (GIANNINI & TAVANI), Spiroplectinella carrinata (D’ORBIGNY), Lenticulina vortex (FICHTEL & MOLL), Heterolepa sp., Gyroidina sp., Cibicidoides sp., Marginulinopsis sp., Dentalina sp.), and second, near the boundary, the Oligocene species Globigerina ciperoensis disappeared. Furthermore, correlation with Oligocene sedimenta- ry rocks in the wider Syrian regions was also helpful. KRASHENINNIKOV et al. (1996) reported the regres- sive nature of the Oligocene deposits. In the Palmyrids the Oligocene marine sedimentary regime terminated at the Neogene boundary, and the marine Palaeogene is unconformably and transgressively overlain by marine Lower Miocene deposits. 6. PALAEOECOLOGY AND CLIMATIC CHANGES Planktonic foraminifera have great potential in palaeo- ecological studies (MURRAY, 1991a). These tiny monocellular organisms with calcite shells are distrib- uted throughout the world seas and oceans, from the polar water masses to the equator, and have different depth preferences of habitat in a stratified water col- umn (HEMLEBEN et al., 1989; MURRAY, 1991a; PEARSON, 1998). Biotic and abiotic factors affect their diversity, morphology, and distribution. Abiotic 26 Geologia Croatica 59/1 factors which may influence the distribution of plank- tonic foraminifera are temperature, salinity, water density, nutrients, light, turbidity, and currents (HAL- LOCK, 1987; HEMLEBEN et al., 1989; MURRAY, 1991a). Biotic factors include food supply, symbiotic relationships, productivity and interfaunal relationships (BÉ, 1982; MURRAY, 1991a; HALLOCK et al., 1991). Planktonic foraminifera are, therefore, very useful in palaeooceanological and palaeoclimatological studies. Much of the world oceans in tropical and subtropical areas are well stratified and oligotrophic. The ecology of the various species in these environments is closely related to their preferred niche in the water column (HEMLEBEN et al., 1989; MURRAY, 1991a; PEAR- SON, 1998; COXALL et al., 2000; WADE, 2004; SEX- TON et al., 2006). In general, planktonic foraminiferal species live in two preferred depth habitats: (1) Shallow-dwelling planktonic foraminifera tend to have thinner or more porous, less dense shells, more globular chambers and they are often spinose (PEAR- SON, 1998). The function of spines is to carry exter- nal cytoplasm with symbionts and to prevent escape of prey (HEMLEBEN et al., 1989; PEARSON, 1998). Shallow-dwelling species have their primary aperture usually in the central position at the umbilical side of the test (PEARSON, 1998). Some of them have mul- tiple supplementary apertures. Isotope analyses of the planktonic foraminiferal calcite shells provide one of the most important insights into oceanographic changes during Earth history. Stable isotope studies of the sur- face dwelling planktonic foraminifera usually indicate the lightest δ18O and heaviest δ13C values in modern as well as in fossil planktonic foraminiferal shells. (2) The majority of modern deeper-dwelling forms and some ancient examples tend to have more angu- lar and flattened chambers. The position of a primary aperture is more extraumbilical and there are no supple- mentary apertures (PEARSON, 1998). Detailed isotope analyses from two species Turborotalia pomeroli and T. cerroazulensis from the Adriatic Sea indicate a thermo- cline habitat for the Turborotalia cerroazulensis group (PREMEC FUĆEK & PEARSON, 2006). Species with- in the genera Subbotina and Catapsydrax are interpreted as having occupied a relatively deep thermocline habitat (PEARSON et al., 1993, 2001; SEXTON et al., 2006). Late Eocene The Upper Eocene succession of the Syrian wells con- tains a rich and diverse planktonic foraminiferal asso- ciation. Muricate forms including Acarinina medizzai and A. collactea have only been represented in zone E14. Previous isotope investigations of acarininids show the lightest δ18O values suggesting a habitat in the uppermost part of the water column. Most posi- tive δ13C values indicate a relationship with algal sim- bionts (SHACKLETON et al., 1985; PEARSON et al., 1993; D’HONDT et al., 1994; WADE, 2004; SEXTON et al., 2006). In the analysed samples, few species of Globigerinatheka in Zone E14 and Zone E15/E16 have been found. The Eocene genus Globigerinath- eka includes spinose forms (PREMEC FUĆEK et al., 1998), as in many modern species in tropical and sub- tropical regions (HEMLEBEN et al., 1989), possessing algal symbionts. They are limited to the shallow, mixed layer of the oceans and seas because of the photosyn- thetic requirements of their algae (BÉ, 1982; MUR- RAY, 1991a). These aforementioned species indicate a subtropical to warm climatic bioprovince for the east Mediterranean area during the late Eocene. Representa- tives of the non-spinose genus Turborotalia (T. pomero- li, T. cerroazulensis and T. cocoaensis) occupy an upper thermocline habitat (PEARSON et al., 2001; WADE, 2004; PREMEC FUĆEK & PEARSON, 2006). Stable isotope records of the turborotalid tests show relatively light δ13C signals suggesting that they have no associa- tion with algal symbionts (PREMEC FUĆEK & PEAR- SON, 2006). During the late Eocene, a few extinctions occurred. Acarinina medizzai and Acarinina collac- tea became extinct at the end of zone E14. Due to the absence of the zonal marker Globigerinatheka semiin- voluta, the last appearance of these two species has been used to approximately define the E14/E15 boundary (see distribution range of A. medizzai in PEARSON et al., 2006). Globigerinathekids decline in abundance and diversity and at the lower part of the E15/E16 (P16/P17) zone become extinct. In BERGGREN & PEARSON (2005), the LO of Globigerinatheka mark the top of the zone E15. The most dramatic extinction event happened close to the Eocene/Oligocene boundary when the last specimens of Turborotalia cerroazulensis (HOWE & WALLACE), T. pomeroli (TOUMARKINE & BOLLI) and T. cocoaensis (CUSHMAN) disappeared. Also Cribrohantkenina inflata (HOWE) disappeared almost simultaneously, while the species Turborotalia increb- escens (BANDY) and Turborotalia ampliapertura (BOLLI) persisted in the early Oligocene. In the same horizons, typical Palaeogene opportunistic foraminifera including biserial heterohelicids, low spired subboti- nids, and tenuitellids (HALLOCK et al., 1991) became more and more frequent in assemblages. Eocene/Oligocene boundary The significant changes of planktonic foraminif- eral assemblages indicate a general cooling trend and eutrophication of the euphotic zone during late Eocene and Oligocene times (KELLER, 1983; BOERSMA & PREMOLI SILVA, 1991). A highly diversified, sub- tropical to warm fauna, where a K-mode life strategy predominated, was gradually replaced by less diverse assemblages dominated by r-strategy taxa indicat- ing cooler waters. The Eocene/Oligocene boundary is marked by the extinction of Hantkenina. The climate event (Oi–1) occurs 200 kyr after the boundary (WADE & PÄLIKE, 2004) and is the result of the ocean tem- perature drop, the formation of Antarctic ice sheets and the development of heavy cold water circulation locally 27Hernitz Kučenjak et al.: Planktonic Foraminiferal Biostratigraphy of the Late Eocene and Oligocene... on the bottom of the ocean (CAVELIER et al., 1981; ZACHOS et al., 1996, 2001; MACKENSEN, 2004; WADE & PÄLIKE, 2004). The results of cooling have been a shallowing of thermocline depth and reduction in the abundance of shallow- and warm-water species (SPEZZAFERRI et al., 2002). The faunal overturn is indicated by the extinction of specialised Eocene forms (K-strategists), such as turborotalids, globigerinathek- ids, hantkeninids, and their replacement by generalised globigerinid form species. In addition, the decrease in the size of specimens is remarkable, as well as increased abundances of the opportunistic taxa and cool water indices, increased numbers of the non spinose, deeper dwelling forms, and reduction in diversity (PREMOLI SILVA & BOERSMA, 1988; BOERSMA & PREMOLI SILVA, 1991). Oligocene The investigated pseudohastigerinids, chiloguembel- inids and tenuitelids within the planktonic foraminif- eral association suggest cooler water conditions in the early Oligocene (SPEZZAFERRI & PREMOLI SILVA, 1991). Pseudohastigerinids did not persist into Zone O2. The extinction of Chiloguembelina cubensis marks the top of Zone O4. Species of the Globigerina ciper- oensis group (G. ciperoensis, G. angulisuturalis) were best adapted to the Late Oligocene environmental con- ditions. They possess a small lowered trochospiral test with a cancellate and spinose wall texture. These spe- cies are abundant at low latitudes outside upwelling areas, and they seem to prefer higher salinity water conditions (SPEZZAFERRI & PREMOLI SILVA, 1991; SPEZZAFERRI, 1994). In Zone O6, very tiny microperforate and the rare species Streptochilus pris- tinum (Pl. 6, Fig. 10) have been found. Furthermore, Globigerinoides primordius has its first occurrence in the planktonic foraminiferal assemblage of the late Oli- gocene. This species with a smooth and spinose wall texture indicates a shift to warmer climatic conditions in the Late Oligocene. In the Late Eocene, predominance of the plank- tonic foraminifera, i.e. very low numbers of benthic foraminifera (Cibicidoides, Lenticulina, Marginulinop- sis, Heterolepa, Tritaxia, Anomalinoides) implies sedi- mentation in a deeper, open-sea environment (VAN DER ZWAAN et al., 1990; MURRAY, 1991b). A grad- ual increase of the benthic foraminiferal proportions (Cibicidoides, Lenticulina, Spiroplectinella, Gyroidina, Neoeponides, Marginulinopsis, Heterolepa, Stilostomel- la, Dentalina) upwards through the Oligocene interval indicates shallowing of the sedimentary environment (VAN DER ZWAAN et al., 1990; MURRAY, 1991b). 7. CONCLUSION The Palmyride area in Syria contains a succession of Upper Eocene to Upper Oligocene deposits. On the basis of a rich planktonic foraminiferal association, bio- zones from E14 (P15) to O6 (P22) have been identified. Biostratigraphic zonal boundaries are determined on the last occurrence of the index taxa. Significant changes marked by the extinction of muricate forms, except for small acarinids, have occurred at the beginning of Zone E14. During the Late Eocene, the number of warm shallow dwelling species decreases, thus indicating the onset of global cooling, which culminated in the earli- est Oligocene. This significant climatic change is well documented by the planktonic foraminiferal assem- blage collected from the studied area. A faunal over- turn is indicated by the extinction of specialized Eocene forms (K-mode life strategy), such as turborotalids, glo- bigerinathekids, hantkeninids and their replacement by cooler, opportunistic globigerinid forms. The early Oli- gocene, as a period of glacial episodes, is characterised by dominance of the r-strategist planktonic foraminif- eral species, such as pseudohastigerinids, chiloguem- belinids, globigerinids, and tenuitelids. The planktonic foraminiferal association of the Late Oligocene shows a trend towards warming, due to the presence of speci- mens from the Globigerina ciperoensis group and Glo- bigerinoides primordius. A very low number of benthic foraminifera in the association imply sedimentation in the deep, open-sea environment during the Late Eocene. Through the Oli- gocene, the proportion of benthic foraminifera in the assemblage gradually increased, thus indicating the shallowing of the sedimentary environment, connected with the global sea level decrease and regional tectonic events. Acknowledgements We thank members of the Palaeogene Planktonic Foraminiferal Working Group for discussion on tax- onomy and biostratigraphy of Palaeogene planktonic foraminifera. We thank Bridget Wade for valuable com- ments and constructive review of this manuscript. We also thank Vlasta Ćosović for helpful discussion and critical review. This research was supported by INA– Industrija nafte d.d. Zagreb, who also provided the sam- ples from the Syrian wells. 8. REFERENCES BÉ, A.W.H. (1982): Biology of planktonic foraminifera.– In: BUZAS, M.A. & SEN GUPTA, B.K. (eds.): Notes for a Short Course, 219, University of Tennessee, Dep. Geol. Sci., Studies in Geology, New Orleans, 51–89. BERGGREN, W.A. & MILLER, K.G. (1988): Paleogene tro- pical planktonic foraminiferal biostratigraphy and magne- tobiochronology.– Micropaleontology, 34/4, 362–380. 28 Geologia Croatica 59/1 BERGGREN, W.A. & PEARSON, P.N. (2005): A revised tropical to subtropical Paleogene planktonic foraminifera zonation.– Journal of Foraminiferal Research, 35/4, 279– 298. BERGGREN, W.A., KENT, D.V., SWISHER C.C. & AUB- RY, M. (1995): A revised Cenozoic geochronology and chronostratigraphy.– In: BERGGREN, W.A., KENT, D.V., AUBRY, M. & HARDENBOL, J. (eds.): Geochronology, Time Scales and Global Stratigraphic Correlation. Special publication of Society for Sedimentary Geology. Tulsa, 129–212. BLOW, W.H. (1979): The Cainozoic Globigerinida, Vol. 3.– E. J. Brill, Leiden, 1452 p. BOERSMA, A. (1988): Foraminifera.– In: HAQ, B.U. & BOERSMA, A. (eds.): Introduction to Marine Micropa- leontology. Elsevier Science, Singapore, 19–78. BOERSMA, A. & PREMOLI SILVA, I. (1991): Distribution of Paleogene planktonic foraminifera – analogies with the Recent?– Palaeogeography, Palaeoclimatology, Palaeoe- cology, 83, 29–48. BOLLI, H.M. (1957): Planktonic foraminifera from the Eocene Navet Formation and San Fernando Formations in Trinidad, B. W. I.– In: LOEBLICH, A.R.Jr., TAPPAN, H., BECKMANN, J.P., BOLLI, H.M., MONTENARO GAL- LITELLI, E. & TROELSEN, J.C. (eds.): Studies in Fora- minifera. Bulletin of the United States National Museum, 215, 155–172. BOLLI, H.M. & SAUNDERS, J.B. (1985): Oligocene to Holocene low latitude planktic foraminifera.– In: BOLLI, H.M., SAUNDERS, J.B. & PERCH-NIELSEN, K. (eds.): Plankton Stratigraphy. Cambridge University Press, Cam- bridge, 155–262. BREW, G.E. (2001): Tectonic evolution of Syria interpreted from integrated geophysical and geological analysis.– PhD Thesis, Cornell University, Ithaca, New York, 323 p. BREW, G., BARAZANGI, M., AL-MALEH, A.K. & SAWAF, T. (2001): Tectonic and geologic evolution of Syria.– GeoArabia, 6/4, 573–616. CAVELIER, C., CHATEAUNEUF, J., POMEROL, C., RABUSSIER, D., RENARD, M. & VERGNAUD-GRAZ- ZINI, C. (1981): The geological events at the Eocene/Oli- gocene boundary.– Palaeogeography, Palaeoclimatology, Palaeoecology, 36, 223–248. COXALL, H.K., PEARSON, P.N., SHACKLETON, N.J. & HALL, M.A. (2000): Hantkeninid depth adaptation: an evolving life strategy in a changing ocean.– Geology, 28/1, 87–90. D’HONDT, S., ZACHOS, J.C. & SCHULTZ, G. (1994): Stab- le isotops signals and photosymbiosis in Late Paleocene planktic foraminifera.– Paleobiology, 20/3, 391–406. HALLOCK, P. (1987): Fluctuations in the trophic resource continuum: A factor in global diversity cycles.– Paleoce- anography, 215, 457–471. HALLOCK, P., PREMOLI SILVA, I. & BOERSMA, A. (1991): Similarities between planktonic and larger forami- niferal evolutionary trends through Paleogene paleoceano- graphic changes.– Palaeogeography, Palaeoclimatology, Palaeoecology, 83, 49–64. HEMLEBEN, C., SPINDLER, M. & ANDERSON, O.R. (1989): Modern Planktonic Foraminifera.– Springer-Ver- lag, New York, 363 p. HERNITZ KUČENJAK, M., PREMEC FUĆEK, V. & SLAV- KOVIĆ, R. (2005): Planktonic foraminifera turnover at the Eocene/Oligocene Boundary (Palmyra Region, Syria).– In: VELIĆ, I., VLAHOVIĆ, I. & BIONDIĆ, R. (eds.): 3. Hrvatski geološki kongres, Opatija, 2005. Knji- ga sažetaka, Zagreb, 55–56. IACCARINO, S.M., PREMOLI SILVA, I., BIOLZI, M., FORESI, M., LIRER, F. & PETRIZZO, M.R. (2005): Practical Manual of Oligocene to Middle Miocene Plank- tonic Foraminifera.– International School on Planktonic Foraminifera, Universita degli Studi di Perugia, Universi- tà degli Studi di Parma, Universita degli Studi di Milano, Perugia–Parma–Milano, 124 p. KELLER, G. (1983): Biochronology and paleoclimatic impli- cations of Middle Eocene to Oligocene planktonic forami- niferal faunas.– Marine Micropaleontology, 7, 463–486. KRASHENINNIKOV, V.A., GOLOVIN, D.I. & MOURAVY- OV, V.I. (1996): The Paleogene of Syria – Stratigraphy, Lithology, Geochronology. – Geologisches Jahrbuch Rei- che B, B 86, 136 p. LOEBLICH, A.R.Jr. & TAPPAN, H. (1988): Foraminiferal Genera and Their Classification.– Van Nostrand and Rein- hold Company, New York, 2. Vols., 970 p. LUČIĆ, D. & FORŠEK, G. (2000): Palmyride evolution: geologic, stratigraphic and structural overview (Cen- tral Syria).– In: VLAHOVIĆ, I. & BIONDIĆ, R. (eds.): 2. Hrvatski geološki kongres, Cavtat – Dubrovnik, 17– 20.05.2000., Zbornik radova, Institut za geološka istraživa- nja, 311–316. MACKENSEN, A. (2004): Changing Southern Ocean palae- ocirculation and effects on global climate.– Antarctic Sci- ence, 16/4, 369–386. MURRAY, J.W. (1991a): Ecology and distribution of plank- tonic foraminifera.– In: LEE, J.J. & ANDERSON, O.R. (eds.): Biology of Foraminifera. Academic Press, London, 255–285. MURRAY, J.W. (1991b): Ecology and Paleoecology of Ben- thic Foraminifera.– Longman Scientific & Technical, Essex, 397 p. PEARSON, P.N. (1998): Stable isotopes and the study of evo- lution in planktonic foraminifera.– In: NORRIS, R.D. & CORFIELD, R.M. (eds.): Isotope Paleobiology and Pale- oecology. Paleontol. Soc. Papers, 4, 138–178. PEARSON, P.N., SHACKLETON, N.J. & HALL, M.A. (1993): Stable isotope paleoecology of middle Eocene planktonic foraminifera and multi-species isotope stra- tigraphy, DSDP SITE 523, South Atlantic.– Journal of Foraminiferal Research, 23/2, 123–140. PEARSON, P.N., DITCHFIELD, P.W., SIGNANO, J., HAR- COURT-BROWN, K.G., NICHOLAS, C.J., OLSSON, R.K., SHACKLETON, N.J. & HALL, M.A. (2001): Warm tropical sea surface temperatures in the late Cre- taceous and Eocene epochs.– Nature, 413, 481–487. PEARSON, P.N., OLSSON, R.K., HUBER, B.T., HEMLE- BEN, C. & BERGGREN, W.A. (2006): Atlas of Eocene Planktonic Foraminifera.– The Cushman Foundation for Foraminiferal Research, Special Paper, 41, in press. 29Hernitz Kučenjak et al.: Planktonic Foraminiferal Biostratigraphy of the Late Eocene and Oligocene... PREMEC-FUĆEK, V., BABIĆ, Lj., BAJRAKTAREVIĆ, Z. & GUŠIĆ, I. (1998): Planktonic foraminiferal biostratigra- phy of the Middle to Upper Eocene succesion in the north Adriatic Sea.– Dela–Opera SAZU 4. razr., 34/2, 255–271. PREMEC-FUĆEK, V. & PEARSON, P.N. (2006): Isotope records from Turborotalia cerroazulensis and Turborota- lia pomeroli near the middle/late Eocene boundary (North Adriatic Sea, Croatia).– FORAMS 2006, Abstract book, Natal (in press). PREMOLI SILVA, I. & BOERSMA, A. (1988): Atlantic Eocene planktonic foraminiferal historical biogeography and paleohydrogeographic indices.– Palaeogeography, Palaeoclimatology, Palaeoecology, 67, 315–356. PREMOLI SILVA, I. & PETRIZZO, M.R. (2006): Practical Manual of Eocene Planktonic Foraminifera.– Internatio- nal School on Planktonic Foraminifera, Universita degli Studi di Perugia, Universita degli Studi di Milano. Peru- gia, 248 p. SEXTON, Ph.F., WILSON, P.A. & PEARSON, P.N. (2006): Palaeoecology of late middle Eocene planktic foraminife- ra and evolutionary implications.– Marine Micropaleonto- logy, 60/1–6, 1–15. SHACKLETON, N.J. CORFIELD, R.M. & HALL, M.A. (1985): Stable isotope data and the ontogeny of Paleo- cene planktonic foraminifera.– Journal of Foraminiferal Research, 15/4, 321–336. SPEZZAFERRI, S. (1994): Planktonic foraminiferal biostra- tigraphy and taxonomy of the Oligocene and lower Mio- cene in the oceanic record. An overview.– Paleontographi- ca Italica, 81, 1–187. SPEZZAFERRI, S. & PREMOLI SILVA, I. (1991): Oligocene planktonic foraminiferal biostratigraphy and paleoclimatic interpretation from Hole 538A, DSDP Leg 77, Gulf of Mexico.– Palaeogeography, Palaeoclimatology, Palaeoe- cology, 83, 217–236. SPEZZAFERRI, S., BASSO, D. & COCCIONI, R. (2002): Late Eocene planktonic foraminiferal response to an extraterrestrial impact at Massignano GSSP (Northeastern Appennines, Italy).– Journal of Foraminiferal Research, 32/2, 188–199. STAINFORTH, R.M., LAMB, J.L., LUTERBACHER, H., BEARD, J.H. & JEFFORDS, R.M. (1975): Cenozoic planktonic foraminiferal zonation and characteristics of index forms.– The University of Kansas Paleontological Contributions, 62, 425 p. SUBBOTINA, N.N. (1947): Foraminifery datskikh i paleoge- novykh otlozhenii Severnogo Kavkaza [Foraminifera of Dacian and Palaeogene deposits of northern Caucasus – in Russian].– In: Mikrofauna neftyanykh mestorozhde- nii Kavkata, Emby I Srednei Azii. Vesesoyuznyi nauchno- issledovatel’skii geollogo–razvedochni neftyanoi institut (VNIGRI), Trudy, Lengostoptekhizdat, 39–160. TOUMARKINE, M. & LUTERBACHER, H. (1985): Pale- ocene and Eocene planktic foraminifera.– In: BOLLI, H.M., SAUNDERS, J.B. & PERCH-NIELSEN, K. (eds.): Plankton Stratigraphy. Cambridge University Press, Cam- bridge, 87–154. VAN DER ZWAAN, G.J., JORISSEN, F.J. & DE STIGTER, H.C. (1990): The depth dependency of planktonic/benthic foraminiferal ratios: constraints and applications.– Marine Geology, 95, 1–16. WADE, B.S. (2004): Planktonic foraminiferal biostratigra- phy and mechanisms in the extinction of Morozovella in the late middle Eocene.– Marine Micropaleontology, 51, 23–38. WADE, B.S. & PÄLIKE, H. (2004): Oligocene climate dyna- mics.– Paleoceanography, 19, 1–16. ZACHOS, J.C., QUINN, T.M. & SALAMY, K.A. (1996): High-resolution (104 years) deep-sea foraminiferal stable isotope records of the Eocene–Oligocene climate transiti- on.– Paleoceanography, 11/3, 251–266. ZACHOS, J., PAGANI, M., SLOAN, L., THOMAS, E. & BILLUPS, K. (2001): Trends, rhythms, and aberrations in global climate 65 Ma to present.– Science, 292, 686–693. Manuscript received April 12, 2006. Revised manuscript accepted June 9, 2006. 30 Geologia Croatica 59/1 PLATE 1 Fig. 1 Acarinina medizzai (TOUMARKINE & BOLLI), Jihar–1, interval 460–470 m, Zone E14. Fig. 2 Acarinina medizzai (TOUMARKINE & BOLLI), Jihar–4, interval 635–655 m, Zone E14. Fig. 3 Acarinina medizzai (TOUMARKINE & BOLLI), detail of the wall texture, Jihar–4, interval 635–655 m, Zone E14. Fig. 4 Acarinina cf. medizzai (TOUMARKINE & BOLLI), Jihar–4, interval 635–655 m, Zone E14. Fig. 5 Pseudohastigerina micra (COLE), Jihar–1, interval 460–470 m, Zone E14. Fig. 6 Turborotalia pomeroli (TOUMARKINE & BOLLI) – Turborotalia ceroazulensis (HOWE & WALLACE) transition form, Jihar–1, interval 460–470 m, Zone E14. Fig. 7 Subbotina corpulenta (SUBBOTINA), Jihar–5, interval 280–290 m, Zone E15/16. Fig. 8 Hantkenina cf. alabamensis CUSHMAN, Jihar–5, interval 310–320 m, Zone E14. Fig. 9 Hantkenina cf. alabamensis CUSHMAN, detail of the wall texture, Jihar–5, interval 310–320 m, Zone E14. Fig. 10 Catapsydrax unicavus BOLLI, Jihar–1, interval 410–420 m, Zone E15/16. Fig. 11 Dentoglobigerina galavisi (BERMUDEZ), Jihar–5, interval 280–290 m, Zone E15/16. Fig. 12 Dentoglobigerina galavisi (BERMUDEZ), detail of the aperture and wall texture, Jihar–5, interval 280– 290 m, Zone E15/16. 31 1 2 3 4 5 6 7 8 9 10 11 12 Hernitz Kučenjak et al. PLATE 1 32 Geologia Croatica 59/1 PLATE 2 Fig. 1 Turborotalia cocoaensis (CUSHMAN), Jihar–5, interval 280–290 m, Zone E15/16. Fig. 2. Turborotalia cocoaensis (CUSHMAN), Jihar–5, interval 280–290 m, Zone E15/16. Fig. 3 Turborotalia cocoaensis (CUSHMAN), detail of the wall texture, Jihar–5, interval 280–290 m, Zone E15/ 16. Fig. 4 Turborotalia cerroazulensis (CUSHMAN), Jihar–5, interval 280–290 m, Zone E15/16. Fig. 5 Turborotalia cerroazulensis (CUSHMAN), Jihar–5, interval 280–290 m, Zone E15/16. Fig. 6 Turborotalia cerroazulensis (CUSHMAN), detail of the wall texture, Jihar–5, interval 280–290 m, Zone E15/16. Fig. 7 Cribrohantkenina inflata (HOWE), Jihar–5, interval 280–290 m, Zone E15/16. Fig. 8 Turborotalia pomeroli (TOUMARKINE & BOLLI), Jihar–5, interval 280–290 m, Zone E15/16. Fig. 9 Turborotalia pomeroli (TOUMARKINE & BOLLI), detail of the wall texture, Jihar–5, interval 280–290 m, Zone E15/16. Fig. 10 Turborotalia ampliapertura (BOLLI), Jihar–5, interval 260–270 m, Zone O1. Fig. 11 Turborotalia increbescens (BANDY) Jihar–5, interval 260–270 m, Zone O1. Fig. 12 Turborotalia increbescens (BANDY) detail of the wall texture, Jihar–5, interval 260–270 m, Zone O1. 33 1 2 3 4 5 6 7 8 9 10 11 12 Hernitz Kučenjak et al. PLATE 2 34 Geologia Croatica 59/1 PLATE 3 Fig. 1 Paragloborotalia nana (BOLLI), Jihar–5, interval 260–270 m, Zone O1. Fig. 2 Pseudohastigerina naguewichiensis (MYATLIUK), Jihar–5, interval 220–230 m, Zone O1. Fig. 3 Pseudohastigerina naguewichiensis (MYATLIUK), detail of the wall texture, Jihar–5, interval 220–230 m, Zone O1. Fig. 4 Dentoglobigerina globularis (BERMUDEZ), Jihar–5, interval 260–270 m, Zone O1. Fig. 5 Dentoglobigerina baroemoensis (LE ROY), Jihar–5, interval 260–270 m, Zone O1. Fig. 6 Dentoglobigerina baroemoensis (LE ROY), detail of the wall texture, Jihar–5, interval 260–270 m, Zone O1. Fig. 7 “Globigerina“ rohri BOLLI, Jihar–5, interval 250–260 m, Zone O1. Fig. 8 Turborotalia ampliapertura (BOLLI), Jihar–5, interval 210–220 m, Zone O2. Fig. 9 Turborotalia ampliapertura (BOLLI), detail of the wall texture, Jihar–5, interval 210–220 m, Zone O2. Fig. 10 Turborotalia increbescens (BANDY), Jihar–4, interval 515–535 m, Zone O2. Fig. 11 Dentoglobigerina sp., Jihar–5, interval 210–220 m, Zone O2. Fig. 12 Dentoglobigerina sp., detail of the aperture and wall texture, Jihar–5, interval 210–220 m, Zone O2. 35 1 2 3 4 5 6 7 8 9 10 11 12 Hernitz Kučenjak et al. PLATE 3 36 Geologia Croatica 59/1 PLATE 4 Fig. 1 Globorotaloides sp., Jihar–1, interval 350–360 m, Zone O3. Fig. 2 Tenuitellinata angustiumbilicata (BOLLI), Jihar–1, interval 350–360 m, Zone O3. Fig. 3 Tenuitellinata angustiumbilicata (BOLLI), detail of the wall texture, Jihar–1, interval 350–360 m, Zone O3. Fig. 4 “Globigerina” tripartita KOCH, Jihar–1, interval 350–360 m, Zone O3. Fig. 5 “Globigerina” venezuelana HEDBERG, Jihar–1, interval 350–360 m, Zone O3. Fig. 6 Tenuitella gemma (JENKINS), Jihar–1, interval 350–360 m, Zone O3. Fig. 7 Globigerina angulisuturalis (BOLLI), Jihar–5, interval 190–200 m, Zone O4. Fig. 8 Globigerina angulisuturalis (BOLLI), detail of the wall texture, Jihar–5, interval 190–200 m, Zone O4. Fig. 9 Globigerina angulisuturalis (BOLLI), detail of the wall texture, Jihar–5, interval 190–200 m, Zone O4. Fig. 10 “Globigerina” venezuelana HEDBERG, Jihar–1, interval 310–320 m, Zone O4. Fig. 11 Chiloguembelina cubensis (PALMER), Jihar–5, interval 190–200 m, Zone O4. Fig. 12 Chiloguembelina cubensis (PALMER), detail of the wall texture, Jihar–5, interval 190–200 m, Zone O4. 37 1 2 3 4 5 6 7 8 9 10 11 12 Hernitz Kučenjak et al. PLATE 4 38 Geologia Croatica 59/1 PLATE 5 Fig. 1 Globigerina ciperoensis (BOLLI), Jihar–4, interval 455–475 m, Zone O5. Fig. 2 Cassigerinella chipolensis (CUSHMAN & PONTON), Jihar–1, interval 250–260 m, Zone O5. Fig. 3 Cassigerinella chipolensis (CUSHMAN & PONTON), detail of the wall texture, Jihar–1, interval 250–260 m, Zone O5. Fig. 4 Globigerina ciperoensis (BOLLI), Jihar–5, interval 160–170 m, Zone O6. Fig. 5 Paragloborotalia opima (BOLLI), Jihar–4, interval 455–475 m, Zone O5. Fig. 6 Paragloborotalia opima (BOLLI), detail of the wall texture, Jihar–4, interval 455–475 m, Zone O5. Fig. 7 Globigerina ciperoensis (BOLLI), detail of the wall texture, Jihar–5, interval 160–170 m, Zone O6. Fig. 8 Paragloborotalia nana (BOLLI), Jihar–5, interval 180–190 m, Zone O5. Fig. 9 Paragloborotalia nana (BOLLI), detail of the wall texture, Jihar–5, interval 180–190 m, Zone O5. Fig. 10 Streptochilus pristinum BROENNIMAN, Jihar–5, interval 160–170 m, Zone O6. Fig. 11 Globigerina angulisuturalis (BOLLI), Jihar–1, interval 220–230 m, Zone O6. Fig. 12 Globigerina angulisuturalis (BOLLI), detail of the wall texture, Jihar–1, interval 220–230 m, Zone O6. 39 1 2 3 4 5 6 7 8 9 10 11 12 Hernitz Kučenjak et al. PLATE 5 40 Geologia Croatica 59/1