GEOL. CROAT. 50/2 21S - 223 3 Figs. I Tab. 2 PIs. ZAGREB 1997 Alveolinas From the Bunic Section (Lika, Croatia) Katiea DROBNE i and Mladen TRUTIN' Key words: Alveolina, A. liislrica, A. rakoveci, Palaeo­ biogeography, Biostratigraphic correlation , Cuisian, Adriatic carbonate platform, Bunit, Croatia, Golez, Slovenia, Hrgucl, Herzegov ina. Abstract The Sunie section of Palaeogene carbonates is exposed in a tec­ tonic window through the Dinari c tectonic unit s in the Kozjak valley in the central parI of the Lib region (Croatia). The Lower Eocene limestones in this section yielded All'colina hisfrica .I'eplel1!riollali.l' and A. rakol'(:ci. These two species characterize a particular facies of shallow waler deposits during Mid dle 10 Late Cuisian times, as observed ul Go1c1 and Voz on the north-western margin of the Adri ­ atic and also at Li .~tica and Hrgud in Herzegovina. Thi s is in cont rast to Alveolina assemblages of the same age composed of A. lel'all/illa, Peri/ocl/lilla darnlafilla. CuskillUlill(/ /iI)//l"I/ica. which characterize the sha llow transgressive deposits of the coastal and insu lar region s in particular at the PiCan and Benkovac sections. The Bunic Alveol ina assemb lage indicates that the limestones in the tectonic window fonned part of the sedimen tary realm represent­ ing the north -eastern margin of the Ad ri atic platform. Thi s also su p­ ports Herak' s tectonic model by distinguishing two tectonically sup ­ erimposed carbonate platforms, the Di//(/ricIIII/ and the Ad,.iatiC/lIIl, separated by an interplatfonn basin called the Epiad,.ia/iclIIll. I. INTRODUCTION In centra l Lika (Croatia) the Palaeogene strata crop out ovcr a very restricted area (Fig. 1). The larges t occurrence of Eocene limestone and flysch is located between Buni eS and Canak villages, 23 km south of the Plitvice Lakes. The rudist limestones of the Upper Cre­ taccous are surrounded by tectonic contacts, For a few metres only, the original transgressive contact betwecn the rud ist limcstones and the overlying Palaeogene car­ bonates has been observed by M. Spari ca (POLSAK et aI., 1978; SPARICA. 1978). These outcrops of Palaeogene strata ini t iated two hypothescs to exp lain their origin, either as erosional remnants of a pa laeostructural syncline, limited partly by fault s (SP ARIC A, 1978, p. 292. PI. I) or Eocene windows belongi ng to the subjacent unit of the Adriatic I I.Rakovec In stit ute of Palaeo nto logy ZRC SAZU, Gosposka 13, SLO-IOOO Ljubljana, Sloven ia. 2 INA -Consulting, Savska 88a, HR 10000 Zagreb, Croatia. carbonate platform (Adriaticum) covered by the Dinaric carbonate platform (DinariclIm) (HERAK, 1986). The schematical cross-section given in Fig. 1 corre­ sponds to the former interpretation, In between the Adriaticum and DinaricLlnI platforms, Herak recognize an interplatform sedimentary belt, named Epiadriati­ cum, extending from NW Slovenia to Montenegro (Fig, 3 and HERAK, 1985, 1987, 1989, 1991 . 1993) . Untill 1985 investigations were carried out within the fram e of the project entitled "Palaeogene Forami­ nifera of Carbonate Development", organized by INA­ Naftaplin. Researchers from Zagreb and Ljubljana cooperated with this and the BUllieS locality was includ­ ed in these studies. Among the foraminifcra the Alveo/i­ na species were studied in more detail than other species. Selected species of the genus Alveolina were used for biostratigraphic correlation of the contempora­ neous sections along the Adriatic coast and for compari­ son with the Buni" fauna (DROBNE. 1977; DROBNE et aI., in press). The aim of this paper is to present the nature and the probable causes of the fauni stic similarities in the Alve­ olina associations from Buni eS and the Adriatic platform. 2. THE BUNIC SECTION The Palaeogene strata crop out over a distance of 10 km along the very narrow Kozjan valley. The belt of limestone is not continuous. Flysch sed iments are visi­ ble for less than I km along the road (Fig. I). The Bunic-Kozjan section (1-9-J) with the collected samples Bu-Ko from 11 to 4 is located on the southwestern slope of the valley, approximately southeas t of Canak viltage. The samples Bu-Ko 64-67 were taken from the bottom of the valley below, in front of the main secti on (Fig. 2a). The base of the logged section is marked by the rud­ ist limestones of Senonian age at an altitudc of 965 m. Probably, there is a tectonic contact between the Senon­ ian and Eocene strata. The total lcngth of the outcrop­ ping section amounts approximately to 400 m, and the thickness of the al veolina-nummulitc limestone to 120 This paper was presented at the scientific meeting dedicated to the 80th anniversary of the life of Professor Milan Herak, held on March Sth, 1997 in Zagreb 216 o SOOm 1 2 3km '-'--'-~~-~. ------'. A 1000 750 500 250 A ~~.HE!,IP'T"'AL GEOLOGICAL PROFILE o SOOm 1 2km " , B LEGEND 9 -- f N ~ 1 :"' : '". 2~ § 3 _ ••• , 48 Q 5~ K2 E3 - 01 6_ K1 E2.3 7 /"" E1.2 8~ Fig. I Location and geological map of the s!Lldy area (modified after SPAR1CA, 1978, tab. 1), Legend: 1) Quaternary: 2) Upper Eocene/Lowe! Oligocene - breccias: 3) Middle and Upper Eocene - marls, rarely sandstones; 4) Lower Eocene - limestone with larger foraminifera: 5) Upper Cretaceous - limestones, dolomites; 6) Lower Cretaceous and Upper Jurassic, on the map only Lower Cretaceous: 7) position of Bunie sectioll (I-9-J); 8) tectonic lines; 9) transgressive contact Cretaceous/Palaeogcnc considered by SPAR leA (1978), m. The logged section ends at sample Bu-Ko 4 (Figs. 2a, 2b) where the section is interrupted by a fault (Fig. 2b). The inclination of strata varies from 30-45°, and their strike is in NNE direction. The beds are in inverse position, and are partially folded. The limestone is (cetonized and cut by calcitic veins. Due to the dense vegetation the success ion of [ayers can not be easily observed. Beds of 30-70 em thickness prevail, ailernat ing with rare, thicker beds of 1.0-1.5 m. In the sequence packs tones to wackstones are domi­ nant. The foraminifera are poorly preserved, their shells, regenerated during life, were broken by post­ diagenetic microleclonic events (Plate I). 3. ALVEOLINA FROM THE BUNIC SECTION The study of the A!veolina species is based on 8 samples from the main sequence of the Bunic - Kozjan (1-9-J) section and on 7 samples from isolated localities (Figs. 2a and 2b). The oriented sect ions of Alveolin([ represent 14 species (Tab. 1). This indicates a Middle Cuisian age in the lowe r and middle part of the section , and Upper Cuisian age in the uppermost beds only (Fig. 2b; PI. I. II). There are Tethyan species represented by A. cremae CHECCHIA-RISPOLl, A. schwagcri CHECCHIA-RI­ SPOLI. A. aff. canavarii CHECCHIA-RISPOLl, A. ruetimeyeri HOTTINGER, A. rectiangula DROBNE and others. They have a broad geographical distribution in the Mediterranean, in both carbonate and clastic deposits (CHECCHIA-RISPOLI. 1905; HOTTINGER. 1960; Di SCOTTO, 1966). The appearance of species belonging to the phylogenetic lineage of Alveolino hisfrica is of particular sign ificance. They were first described in SW Slovenia in the Kozina, Slavec and Gold. sections under the specific designation: A. histri­ ca his/rica DROBNE and A. h. septentrionalis DROB­ NE [rom the Middle Cuisian, as well as A. rakoveci Drnilm:: & Tnl1in: i\ lveol illo\s From the Bunk' Scclioll (Lib. Croati a) 217 --------------------------------------------- Fig. ]: a) Topographicallllllp show ing the position of the Bunic secl ion and isolatcd poims ( Bll~Ko 61 -67). b) Slratigraphic co lumn of Ihe Blillic logged section, lilhology mid main spccies of All'co /il/(f (afle r DROBNE et al" in press). Legend: 1) limestone; 2) micriti c limestone; 3) weakl y bedded limesionc; 4) tectonic linc: 5) isolatcd point; 6) section line. DROB NE from the Upper Cui sian. Members of th is lineage al so occur on the Island of Krk, on the northern Yoz promontory (DROBNE, 1977 , 93-95,78, Ill). In the Eocene limestone ex tcnding rrom Ci ca rija to Tri ­ es te, a perfectly preservcd assemblage with A. rakoveci. was discovered at the Rosandra panorama viewpoint at the Slovenian -llali an border (personal data). North of the KaravankeMts. in the Ivartnik section, the presence of a few A. II. his/rica specimens was recorded by DROB E e t al. ( 1977, Tab.l , PI. I , Figs. 5-7). Thi s locality belongs to a particular tectonic domain (Fig. 3), th e so-ca ll ed Dinari c- Alpidic complex of HERAK (1991). In Herzegovi na, the species frolll the A. hisfrica lin­ cagc were also found in the Listi ca section (personal da ta), and on Mt. I-Irg ud above the historica l city of Stone (DROBNE et aI. , in press). 4. PALAEOGEOGRAPHIC DISTRIBUTION OF SPECIES BELONGING TO THE A. his/rica LINEAGE All occ urrences (except lvartnik, Tab. I) whi ch yie ld representatives of the phylu m A. his/rica are loca­ ted within a narrow res tricted arca extending in NW-S E Dinari c direc tion. T hi s area rep resent s a palaeogeo­ graphic domain interpreted as the north-easte rn margin of thc Adriatic platform. North-Eastwards, this margin is obscured by basinal te rrigenous sed iments along its ex tension, in NW Slovenia (PAYS IC et a I. , 1996) as well as in Herzegov ina (SLISKOYIC et aI. , 1978). T he Adriatic platfonn constituted an isolated shoaly zone in the Centra l Tethy s du ring the Palaeoge ne (HOTTI ­ NGER, 1990). It was drowned at different timcs in dif­ ferent places according to the la tter's re lat ive posit ion with respect to the platform margin, and subsequently covercel by terrigeno us sediments . Therefore, is thc geographically restr icted occurrence of the A. his/rica phylum due to true endem ism, or to env ironme nta l rest riction s corres ponding to a part icu lar facies belt characterizing the plat form margin? The isolated pos iti on of the Palaeogene Adriatic platform in the Tethyan sea may be a good prerequisite for endemi sm. The occurrence of A. his/rica in lvartnik , out sid e or the Adriatic domain would suggest ot her­ wise. However, the palaeogeographic pos iti on of thi s latter loca li ty remain s clear, as thc positio n or the Palaeogene-Eurasian contincntal margin in lile Alpine realm has not been accurately reconstructed. In particll ­ lar the pos iti on of the Karin thian Krapp fe ld olltcrops LJCOlogm LrOallC:l :lUlL Golei Voz BUNle listiea Hrgud Rosandra Alveolina Dobrinj Stolae Ivartnik A. azzarofii 0 0 0 Upper A. rakoveci <0> <0> <0> <0> <0> A. h. septentrionalis <0> <0> <0> <0 > <0 > A. histrica histrica <0> <0 > <0> <0> C A. fornasinii 0 0 U A. aff. canavarii 0 0 0 0 0 I A. cosinensis cosigena 0 0 0 0 0 S A. ruetimeyeri 0 0 0 0 0 I A. cremae 0 0 0 0 0 A A. distefanoi 0 0 0 0 0 0 N A. schwageri 0 0 0 A. cofatiensis 0 0 0 A. carantana 0 0 0 Middle A. rectianguJa 0 0 T"blc I Assoc iation or alveo li n; ror location of scc lion!i !iee Fig. 3. (w here A.. his /rica is absent - Van ]-IINTE, 1963), in relation to Tvartnik is unknown. AlLernatively, the Adriatic area corresponding to the dis tribution of A. hisfrica ex hibits a common sedimen­ tary hi story. Carbo nate sed imentation is continuou s rrom the T1 erd ian to the C ui sian and the pl atform was drowned prior to the base of the Lutetian. Th is charac­ terizes the platform margin in contrast to inncr parts of the platform where the marine carbonate sedimentation began laIc, with the C ui sian transgression, and ended, du ring the Lutetian (DROBNE, 1977). Platform margi ns doubt lessly have habilats ot her than res tricted areas o r the in te rnal parts (HOTTI­ NGER, 1980) and may the re fore del imi t narrow, be lt­ like areas of di stributi on for taxa of the larger forami­ nifera. The present state o/" knowledge does not permit a definite answer to these questions. However, the lin­ ear al ignment of the A. hisfrica occurrences emphas izes the close facies re lationship be tween the Lis tica-Hrgud and the Rosandra-Voz areas (Fig. 3) and just ifies ad­ ding the Bunie A. histrica occurrence into the linear rc­ a im. As a consequence, the Bunie occurrence must be inte rpre ted as a tec tonic window, where a piece of the Adria tic platform margin is expressed from beneath the overthrusted Dinaric leclonic unit. S. CONCLUSION The linear exte ns ion of the distribution of the C uis ian alveol inid species belonging to the A. histrica phy luill . between NE S lo venia and SE Herzegov ina corresponds to the NE margin of the Adriatic platform which constituted an isolated shoaly area in the Tethyan sea. The presence of A. Iiistrica in this narrow belt may ei the r reflect particular environmental conditions a long the platform margin, or represent an area delimi led by endemism, or result from a contribution of bolh factors. Thus, the facies relations bel ween the Cuisian alveolina limestones are significant enough to justify an interpre­ tation of the Bunie alveolina limestone as an intennedi ­ aIY part o f the platform marg in , hidden beneath the overthrusted Dinaric unit (Fig. 3) and emerging in iso­ lated points from below in a tectonic window. Acknowledgement The authors wish to thank the INA-Naftaplin in sti ­ tution , which, many years ago, provided the opportuni ­ ty to study the Bunie section, colleagues Ljubo BAB IC and ]ozica ZUPANIC for pe rmi ssion to use the data froIll the Listica sect ion , colleague Simon PIRC fo r translat ion of the text and nol least Lukas HOTTI ­ NGER for critical remarks and for the enlargement of the palaeogeographic ideas. The authors also thank both our researeh Institutions ZRC SAZU and INA Consull­ ing for support during the invest iga tion and realisa ti on of this s tudy. 6. REFERENCES CHECCHIA-RISPOLI, G. (1905): Sopra aleune Alvco­ line coceniehe della Sicilia. - Pa leontographia ll a l. , II , 147-167, pis. 12-13_ Drobnc & Trut in: Alvcotin:ts From the Bunie Sect ion (Lib. Cro:lli:t) • • + ADRIATIC SEA • I:l.O 5 p c o 50 100km , Di SCOTTO, C,B. ( 1966): Le Alveoline del Gargano nord-orienlale,- Palaeonl. lIal., 6, 65-73, Pisa. DROB NE, K. ( 1977): Alveol ines paleogenes de la Slovonic el de I' lst ric.- Mem. Su iss. Pa leonl. , 99, 132p., 21 pIs. DROBNE, K. , PAVLOVEC, R. & DROBNE, F. (1977): Pal eogene larger Foramin ifera from the area be Lwcen Mczica and Slovenj Gradce (N W Yugo­ slavia).- Razprave SAZU 4. razr. , 20, 88p. , 23 pis., Ljubljana. DROBNE, K., TRUTIN, M. & PAVLOVEC, R. (in press): Paleogene stratigraphy of the Adria tic car­ bonale plalfoIlTI .- Dela - Opera SAZU 4. razr., 34/3, Ljubljana. DROBNE, K., VLA HOVIC, I. , TRUT IN, M. , PAV­ LOVEC, R., COSOVIC, V., BABAC, D. , CIMER­ MAN, F., LUCIC, D. & PAVSIC, J. (199 1): Excur­ sion B - Ravni Kotari, Paleogene.- In: VLAHOV1C~. I. & VELIC, I. (cds.): Some aspecis of Ihe shallow water sed imentation on the Adriatic Carbonate Plat­ form (Permian to Eocene), Excursion guide-book, 2nd Intern. Symposium on the Adriat ic Carbonate Pial form , Zadar, 53-90, 7 pis., Zagreb. " A 2 19 Fig. 3 Geotectonic belts, aftcr HER ­ A K ( 1986, 199 1 - fig. 5) wit h the pos itio ns o f the sec ti ons com posed by alveo tina -num­ mu lite limcsto ne . Legend : A) Structural complex of the Adri­ ,H ic carbonate platform (Adri · allcum); E) Depos it s of pelagic provenance in con nec ti o n with tile InterpJatform belt (cjJiadrj­ (lli(:IIIII): D ) Structura l complex of the Dinaric ca rbonate pl a t­ fo rm (Dil/ariwlII): DA ) T he joi­ nt a rea of the Dinarides and Alp­ id es; S) St ruc tural co mpl ex o f the Inner Dinarides (Su{Jradil/ar­ iCllm) which originated in con ­ nec tion with th e oce.U1 be lt o f the T ethys; black: ultrabas ie, ba­ s ic and associated rocks: P) Pre­ Alpine st ructural complexes (P I - Pannon ian s truc ture, P2 - Se r­ bo-Macedon ian Massif): C) Car­ patho- Ba lka ni an Be lt. A I' El ) tectonic windows within the Oi· nar;cllm; 0 Occurrence of A. hi.l'lrica; .1. Cocval al veolinicl as­ semblages without A. his/rica, shown at the Pi ca n (1 s t ria) and Bcnkovac - Ravni KOtari secti­ o ns (DROB NE , 1977; DROB­ NE et aI., 1991 ). HERAK , M. ( 1985): On Ihe rehuion of Aclrialic and Dinaric strllc tllres.- Razpravc SAZU 4 . raZL, 26, 40 1-414, LjUbljana. HERA K, M. (1986): A new concepl of geoleelOnies of Ihe Dinaridcs .- Acla geol. , 16, 1-42, Zagreb. HERAK, M. (1987): The MohoroviCic diseonlinuily in Yugoslavia.- Aela geol. , 17,5-45, Zagreb. HERAK, M. ( 1989): Rela lionship belween Adrialic and Di naric carbonate platrorms.- Mem. Soc. Geol. It. , 40 ( 1987),289-293. HERAK, M. (1991 ): Dinarides . Mobilislie view of Ihe genesis and structure.- Acta geo!. , 2 1, 35- 1 J 7, Zag­ reb. HERAK, M. ( 1993): Addilional eo nsideralion on Ihe Epiadriat icum, Outer Dinarides.- Geo!. Croatica, 46, 165- 168. HOTTI NGER , L. (1960): Reche rches sur Ics Alveoli­ nes du Paleocene et de j'Eocene.- Mcmoires SlIisscs de Palconlologie, 75-76, 243 p. HOTTINGER, L. (1980) : Reparlilion compa ree des grands Foraminifcrcs de 1a Mer Rouge et de I 'Ocean 220 Inelien. - Ann. Univ. Ferrara (Nuova Serie), Ser. IX, vol. suppl. 6, 1-13. HOTTINGER, L. (1990): Significance of diversity in shallow benthic foraminifcra.- Aui del Quarto Sim­ posio eli Ecologia e Paleoecologia delle Comunita Bentoniche, 35-51, Torino. PAY SIC, J., DOLENEC, T. & HORYAT, A. (1996): KanaJ-Lig Cretaceousffertiary boundary in flysch.­ In: DROBNE, K., GORICAN, S. & KOTNIK, B. (eds.): Tnt.workshop "The role of im pact processes in the geological and biological evolution of planet Earth", 203-209, Ljubljana. POLSAK, A., CRNKO, J, SIMUNIC, An., SIMUN1C, AI., SPAR1CA, M. & JURISA, M. (1978): Osnovna geoloska karla SFRJ I: 100.000. Tumac za list Bihac L33-116.- Inst za geol. islI·az. Zagreb (1967), Save­ zni gcol. Zavod Beograd, 51 p. SLlSKOYIC, T., PAYLOYEC, R. & DROBNE, K. (1978): Older Paleogene in I-Iercegovina. - Zbornik radova 9. kongr. geol. Jugoslavije , 125- 128, Saraje­ vo. SPARICA, M. (1978): Stratigrafija, tektonika i paleo­ geografija podrucja Bunic-Canak u Lici (Hrvatska) (Stratigraphy, tectonics and paleogeography of Bunic-Canak area in Lika (Croalia».- Geol. vjesnik, 30,281-295. Van I-IINTE, J.E. (1963): Zur Stratigraphic unci Mikro­ paltiontologie del' Oberkreide und des Eoz~ins des Krappfeldes.- K~irntell Jahr. Geol. BUllelesanstalt, Sonclerbancl8, 147 p., 22 pis., Wien. Manuscript received April 14, 1997. Revised manuscript accepted November 10, 1997. PLATE I Alvcolina-nllmmlliitc limcstone, A. recfiangll/a DROBNE, A. rakoveci DROBNE, Glomalveolina sp ., Orbifolifes sp., Nummufifes sp., packstone, Du-Ko 64/54.13. 2 Packstone, baclly preserved foraminifera, Bu-Ko 4/5258. All enlarged xl 0, incident light Ol'Obnc & Trutin PLATE I 221 ,. .' . , " : .-, ... , . ' " • : t ... 1 PLATE II Aiveolillo rakoveci DROBNE, [A , axial section, Bu-Ko 64/5417, Upper Cuisian 2 A. rakoveci DROBNE, r A, equatorial scction, Bu-Ko 64/5413, Upper Cuisian 3 A. hislrica seplelliriollalis DROBNE, f A, axial section, Bu-Ko 65/5435 , Upper Cuisian. 4 A. It. septelllriunalis DROBNE, r A, axial section, Bu-Ko 5/5283, Middle Cuisian 5 A. Itislrica hislrica DROBNE, f A, axial section, Bu-Ko 8/5333 , Middle Cuisian 6 A. reclianguia DROBNE, [B, axial scction, Bu-Ko 64/541 I, Upper Cuisian 7 A. dislej{lI/oi CHECCHIA-RISPOLI, [ A, axial section, Bu-Ko 5/5363, Middle Cuisian 8 A. schwageri CHECCHIA-RISPOLI, [A, axial section, Bu-Ko 6/5297, Middle Cuisian 9 A. melimeyeri HOTTINGER, [A, axial section, Bu-Ko 6/5297, Middle Cuisian 10 A. alT. canavorii CHECCHIA-RISPOLI, f A, axial section, Bu-Ko7/53 16, Middle Cuisian II A. cremae CHECCHIA-RISPOLI, r A, axial section, Bu-Ko 10/5375, Middle Cuisian All enlarged xlO, incident light DrobJ1(! & Trlllin PLATE n , 7 • 4It, " , , • , .. . . ' , - ~ '.:,. . " ..... /'~ .:~.~ . ..,.~;.- 223 , , " • 2 224 Geologin Croalica .'iOn ,/ • , , •