Geo log i cal Quar terly, 2012, 56 (4): 833–844 DOI: http://dx.doi.org/10.7306/gq.1058

The Tylawa Lime stones – a re gional marker ho ri zon in the Lower Oligocene of the Paratethys: di ag nos tic char ac ter is tics from the type area

Agnieszka CIUREJ and Grzegorz HACZEWSKI

Ciurej A. and Haczewski G. (2012) – The Tylawa Limestones – a regional marker hori zon in the Lower Oligocene of the Paratethys: di - ag nos tic char acter is tics from the type area. Geol. Quart., 56 (4): 833–844, doi: 10.7306/gq.1058

Three units of lam inated coccolith limestone are used as re gional chronohorizons in the Oligocene of the Outer Carpathians. Two of them – the Tylawa Limestones and the Jasło Limestone – display a sim ilar type of lam ina tion and their discri m ina tion is in some cases prob- lem atic. We pro vide a detailed mesoscopic and micro scopic lithological descri ption of the Tylawa Limestones from the type lo cality at Tylawa and from Rudawka Rymanowska – the best expo sure in the Pol ish Carpathians. The finely lam inated limestone layers are up to 5.5 cm thick and are disperse d through a section more than 100 m thick. They are grouped in cluster s. They dif fer from the younger Jasło Limestone in: (1) an absence of foraminifers, (2) a mass oc cur rence of Reticulofenestra ornata Müller, (3) the presence of voids after pennate dia tom s, (4) dark laminae which are more pronounced than in the Jasło Limestone.

Agnieszka Ciurej, In sti tute of Geo log i cal Sci ences, Pol ish Acad emy of Sci ences, Senacka 1, 31-002 Kraków, Poland, e-mail: [email protected]; Grzegorz Haczewski, Ped a gog i cal Uni ver sity of Kraków, Podchorążych 2, 30-084, Kraków, Poland, e-mail: [email protected] (receiv ed: April 26, 2012; accepte d: May 20, 2012; first publishe d online: Novem ber 15, 2012).

Key words: Tylawa Limestones , Outer Carpathians, coccolith limestone, chronohorizons, Oligocene.

INTRODUCTION and Zagórz hori zons) have been recog nize d and mapped along nearly the whole length of the Carpathians, while a few others have been dis tinguishe d and named local ly. The Oligocene–Lower Miocene depos it s of the Outer The limestones occur as millimetric to decimetric layers of Carpathians are up to ca. 2 km thick and make up as much as a coccolith limeston e. In most sec tions they are split by clastic half of the enti re Upper Juras sic through Lower Miocene suc- depos it s that are usuall y much thicker than the limestone ces sion of the Outer Carpathian fold-and-thrust belt. These themselve s. Cor re la tion of laminae in the Jasło Limeston e has synorogenic depos it s were laid down in a basin whose com mu - shown that the clastic rocks repre sent event depos it s, and the ni cation with the open ocean becam e re stricted in the Early lam i nated lime stone rep re sents the bulk of the geo log i cal time Oligocene (Oszczypko, 2004). The Oligocene sequence con- during which the limestone unit was laid down (Haczewski, sists of a va ri ety of diachronous and lat er ally variable fa cies, 1989). The laminae in the Jasło Limestone and Zagórz Lime- from organic -rich black shales to coarse-grained gravit y-driven stone have been cor re lated across the major tectonic units and mass-flow de posit s. The sequence is poor in stratigraphically fa cies zones of the Outer Carpathians over dis tances up to useful fossil s and the pres ence of many endem ic forms pre- 550 km. Be cause of this the limestone hori zons have been ac- cludes pre cise biostratigraphic corre la ti on with the coeval cepted as chronohorizons (sensu Racki and Narkiewicz, strata of the open ocean. This is why thin inter cala ti ons of pe- 2006). Some general mesoscopic char ac ter is tics help dis tin - lagic coccolith limestone , concen tra ted in disti nct isochronous guish the limestone s from the three major hori zons. These hori zons, have been exten sive ly used as regional strati graphic char ac ter is tics in clude: type of lam i na tion, abun dance of fish mark ers be tween var ious tec tonic units and fa cies since the rem ains, and presence of planktoni c foraminifers. There are, middle of the 20th century (see Jucha, 1957; Jucha and how ever, many lo cal i ties where iden ti fi ca tion of “Jasło-like” Kotlarczyk, 1958; Ślączka, 1959a, b; Koszarski and Żytko, lime stones is un cer tain (e.g., Koráb and Kotlarczyk, 1977). 1961; Jucha, 1969; Haczewski, 1984, 1989; Melinte, 2005; This is be cause of: (1) heavy alter ation of limeston e by sili ci - Kotlarczyk et al., 2006). Three of these hori zons (Tylawa, Jasło fi ca tion, dolomitization, weath er ing, or tec tonic frac tur ing, 834 Agnieszka Ciurej and Grzegorz Haczewski

(2) sub stan tial clastic adm ixture in the limestone that obscure s Studies on the abundant fish fauna in the Tylawa Lime- the iden tity of laminae, (3) the limeston e lay ers be ing too thin stones reveal ed that this, in the narrow strati graphic inter val to study their lam ina ti on or faunal content , and (4) the pres - en com pass ing the Tylawa Limeston es, is clearly dis tinct from ence of limestone lay ers not belong ing to the previ ously de- fish assem blages below and above (Jerzmańska and fined hori zons. The corre la ti on of laminae in the Jasło and Kotlarczyk, 1968, 1981; Kotlarczyk et al., 2006). Zagórz limestone s helps to overcom e dif ficult y (1) in many Jucha (1969) intro duced the name “łupki tylawskie” cases, even when limestone fragm ents are found loose (Tylawa Shales) for the old est ho ri zon, af ter the clas sical lo cal- (Haczewski, 1984, 1989). Clastic adm ixture may result in un- ity in the Dukla Unit. Many map ping ge ol o gists (in clud ing A. even thick en ing and loss of def i ni tion of in di vid ual laminae, Ślączka, pers. comm. to GH, 1998) suggest ed that the Tylawa mak ing them use less for cor re la tion. Shales oc cur as sev eral sep a rate lime stone ho ri zons, The Tylawa Limestone s seem to be involved in most of the stratigraphically close to one an other. The fine, dis tinct lami na - doubtful cases. Even if fine, regu lar lam ina ti on, abundance of tion in the Tylawa Limestone s has not been convinc ingl y corre - fish and the lack of planktoni c foraminifers are valid dis tinc tive lated over distanc es greater than ca. 20 km and the Tylawa char ac ter is tics in clas si cal good ex po sures of typ i cal Tylawa Lime stones seem to rep re sent re cur rent ep i sodes of coccolith Limestone s, the lack of fish rem ains or foraminifers may re flect lime stone de po si tion. That is why Haczewski (1989, pp. a fortu it ously barren fragm ent of elsewhere fossiliferous rock 442–443), pre sent ing a typology and no men cla tur al scheme for at lo cal ities where only thin limeston e lay ers, or small loose the three major chronohorizons of coccolith limestone, named frag ments of weath ered limestone are pres ent. the Tylawa Limestone s in plural , in contra st with singu lar We pro vide here a de tailed de scripti on of the struc ture of names for the Jasło Limestone and Zagórz Limestone . The the Tylawa Limestones as seen mesoscopically as well as in Tylawa Limestones in their type area occur as millimetric to opti cal and electron micro scope images, with the aim of pro- centimetric layers of coccolith limeston e with a to tal thick ness vid ing better cri te ria for their iden ti fi ca tion. We use ma te rial up to ca. 50 cm and are often grouped in cluster s of closely from the orig i nal lo cal ity at Tylawa and from the best expo sure spaced lay ers, all en closed in a sequen ce of host sed im ents up at Rudawka Rymanowska. to ca. 100 m thick. Simi lar lami nated limeston es have been found at a simi lar strati graphic posi ti on in other areas of the Silesian Unit, in the CONCEPT OF THE TYLAWA LIMESTONES Subsilesian and Skole units, and re ferred to the Tylawa Lime- stones ho ri zon (Koszarski and Żytko, 1959; Jucha, 1969; Thin layers of coccolith limeston e in the Carpathian Flysch Kotlarczyk, 1977, 1988; Kotlarczyk et al., 2006). The Tylawa have been first noti ced and reporte d by Uhlig (1882) near Jasło Limestone s occur in the lower part of the Menilite Beds in in a sandstone -and-shale turbidite sequence of the Krosno nannoplankton zone NP 23 of Marti ni (1971) (see Krhovský, Beds. He soon found sim ilar limestone s around Bochnia within 1981). The disti ncti ve fish assem blage was used to de fine dark bi tu mi nous shales of Menilite type (Uhlig, 1884). He re - biozone IPM2 in the ichthyofaunal suc ces sion (Jerzmańska and ferred to them as “...those char acter istic, fish-bear ing cal car e - Kotlarczyk, 1968, 1981; Kotlarczyk et al., 2006). Equiva lent s ous shales from Jasło”. This is the first use of the coccolith of the Tylawa Limestone s have been recog nize d in the Al pine limeston es in the Carpathian Oligocene as a re gional marker foreland ba sin in Austri a (Müller and Blaschke, 1971; Schulz et be tween var i ous fa cies. al., 2005), in the Outer Carpathians from the Czech Repub li c, The Uhlig’s term “Kalkschiefer von Jasło”, af ter transla ti on through Poland, Slovakia and Ukraine to Rom ania to Pol ish and leaving out the “Kalk” part, has turned into “łupki (Kotlarczyk, 1961; Koráb and Kotlarczyk, 1977; Haczewski, jasielskie” (Jasło Shales) and was used for whit ish-weather ing 1989; Krhovský et al., 1992; Melinte, 2005; Melinte- platy limestone s found at vari ous local iti es. The finding that the Dobrinescu and Brustur, 2008). Their recog ni ti on was based on lime stones are ex ten sive re gional chronohorizons, among the the presence of lam inate d limestone s in the lower part of the fa cies units ear lier con sid ered as time-units, be came a major Oligocene succes sion, and was supporte d by data from fish, break-through in the strati gra phy of the Outer Carpathians nannoplankton or both (see ref er ences above). Nannoplankton (Shakyn, 1958; Jucha and Kotlarczyk, 1958; Koszarski and is usuall y pre ferred to fish as a means of rapid biostratigra - Żytko, 1959). Three sepa rat e hori zons of “Jasło Shales” were phical di ag no sis, but dis in te gra tion of the Tylawa Limeston es traced over large ar eas. Jucha (1957) com piled in for ma tion on for nannoplankton anal ysis usu ally re sults in sam ples de scribed the spa tial and strati graphic dis tri bu tion of the limeston es and as bar ren of coccolithophores (see Ciurej, 2009). no ticed that strata re sembling the “Jasło shales” occur also in Pos si ble an a logues of the Tylawa Limestones have been the lower part of the Oligocene sequence in the inner part of the descri bed from the succes sions in other parts of Paratethys Silesian Unit (at Rudawka Rymanowska). Ślączka (1959a, b) Ba sin, east of the Carpathian area, mainly in the Cau casian re - found these limestone s in the outer part of the Dukla Unit and gion (Nagymarosy and Voronina, 1992; Muzylev et al., de scribed them as finely lami nated limeston es simi lar to the 1992). Publi shed de scripti ons seem to suggest that the num - Jasło Shales. He also noti ced that the Jasło Shales proper, sit u - ber and thick ness of the lam inated limestone lay ers in crease to ated higher in the stratigrap hic se quence, are rich in the south and south-east. The lithological descri pti ons pro- globigerinids. In his monograph on the Dukla Unit, Ślączka vided in this paper may be used to evalu ate the sim ilar ity of (1971) confirm ed the persis tent strati graphic posi ti on of the these depos it s to the Tylawa Limeston es. Be sides the “Tylawa Shales” in the frontal part of the Dukla Nappe. lithological simi lar ities, the na ture of the fish as semblag e typ i - cal of the IPM2 zone of Kotlarczyk et al. (2006) should be The Tylawa Limestones – a regional marker horizon in the Lower Oligocene of the Paratethys: diagnostic characteristics from the type area 835 con sid ered a re quired di ag nos tic fea ture of any pos si ble equiv a lents of the Tylawa Limeston es.

METHODS

Sec tions with the Tylawa Limestone s have been logged in the field at a scale of 1:10. Ori ented (top-and-bottom ) sam ples were taken from the com plete thickness of the Tylawa Lime- stones and from the directly ad ja cent host strata of each lime- stone layer. The limestone samples were cut per pen dic u lar to strat i fi ca tion and pho to graphed in uni form light ing con di tions. The pho to graphs were dig i tally as sem bled into a con tin u ous se quence of the lami nated limestones from each lo cality, re pro - duced at the same scale. Mesoscopic lithological de scrip tion of the limeston es was made millimetre by millimetre from the bot tom to the top of each sec tion on the cut and pol ished surface s of the limestone lay ers. Mi cro scopic ex am i na tion was made on stan dard un cov- ered petrographic thin sec tions cut per pen dic u lar to lam i na tion and diag o nall y, at an angle of 50° to lam ina ti on in order to better sep arate var ious lev els within the laminae. The thin sec - tions were studied with an Olym pus SZX9 (trans mit ted light) po lar iz ing mi cro scope with a dig ital camera (Olym pus U-TVO.5XC-2) steered by a com puter using Anal y sis software and using a scanning electron micro scope (SEM), using var i- ous modes of obser va ti on: charge contra st im aging (CCI) and back-scat tered elec trons (BSE). More tech ni cal de tails are given in Ciurej (2010). The SEM–CCI method allows study of an a tom i cal de tails of cal car e ous nannofossils in strongly ce- mented samples that were re garded as bar ren of nannoplankton af ter stan dard sep a ra tion treat ment for cal car e ous nannofossils (Ciurej, 2009).

DETAILS OF THE TYLAWA SECTION

The Tylawa lo cal ity is gen er ally ac cepted (Jucha, 1969; Ślączka, 1973a, 1977) as the type local ity of the Tylawa Lime- stones. The expo sure lies in the eastern part of the Polish Carpathians, on the right bank of the Jasiołka River, ca. 1 km east of the inter nati onal road E371 be tween Svidnik (Slovakia) and Dukla (Fig. 1). The lower part of the Menilite Beds of the Dukla Unit, exposed there, include s, from bottom to top: the Mszanka Sandstone s, the Sub-Cergowa Marls (equiv a lent to the Dynów Marls) and the Cergowa Beds. The Cergowa Beds are bipar tite in this sec tion, with the lower di vi sion of the thick- and thin-bedded Cergowa Sandstone s overlai n by the Cergowa Shales – marly, grey to brownish shales rhythm ical ly alter nat-

Fig. 1. Loca tion of study area A – sim plified geolog i cal map of the Outer Carpathians with the loca tion of the study area: C. F. – Carpathian Foredeep, I. C. – In ner Carpathians, P. B. – Pan nonian Basin, PKB – Pieniny Klippen Belt, T. B. – Transylvanian Ba sin, V. B. – Vi enna Ba sin; B – sim pli fied geo log i cal map of the Pol ish part of the Outer Carpathians (after Książkiewicz, 1972) with loca tion of the sections studied; C – de tailed lo ca tion of Tylawa sec tion; D – detail ed loca tion of the Rudawka Rymanowska sec tion 836 Agnieszka Ciurej and Grzegorz Haczewski ing with thin- and medium -bedded grey micaceous cal car e ous sandstone s. The facie s of the Cergowa Shales lat er ally replaces the Menilite-type dark, organic -rich sili ceous shales. The Tylawa Limestones are interlayered within the Cergowa Shales (Jucha, 1969; Ślączka, 1973a). Detai led exam ina ti on of the 115.3 m thick secti on has re - vealed a total of 18 cm of the Tylawa Limestone s in 12 layers. The thin limestone lay ers are grouped in three cluster s (Figs. 2 and 3). The two higher cluster s, sepa rat ed from one another by ca. 40 m, are most likely those de scribed by Jucha (1969) and Ślączka (1973a). Geo graph ical co or di nates (in WGS 84) of the expo sure of the highest clus ter were de ter mined us ing a hand-held GPS recei ver as: N49°28’18.3” and E21°43’21.3”. The third clus ter of limestone lay ers, not de scribed ear lier, is exposed 65 m below the middle cluster at: N49°28’17.1” and E21°43’28.62”. All lime stone lay ers dis play char ac ter is tic submillimetric to millimetric lam i na tion con sist ing of al ter na - tions of light and dark laminae, though at some levels the mesoscopic visi bil ity of laminae is obscure d on weathered sur- faces. The se quences of laminae dif fer slightly between and within the cluster s in the thicknesse s and propor ti ons of the light and dark com ponents . The lowest clus ter con sists of two lay ers of lami nated lime- stone (Figs. 2 and 3). The lower layer (6 mm thick) is poorly dis cern ible against the en com pass ing black mudstone (TYL 2/07; Fig. 3). It consis ts of a bundle of thin laminae with a predom inant dark com ponent. The other layer lies 10 cm higher and dis plays dis tinct lam i na tion (TYL 3/07; Fig. 3). Laminae of marly claystone are present among the bundles of limeston e lamina cou plets. This layer is un der lain, with a sharp boundary , by non-lam inate d limestone and passes gradu all y up wards into pelletal marly claystone. The middle clus ter con sists of two lay ers of lami nated limestone within a succes sion dom inate d by shales and mudstones (Figs. 2 and 3). The lower layer consis ts of three bundles of limestone lamina couplet s sepa rat ed by grey marly mudstone. Lami na tion in the limeston es within this layer is poorly vis i ble (TYL 5A/07; Fig. 3). The higher layer also com- prises three bundles of eas ily discern ibl e limestone lamina cou - plets sep arated by grey marly mudstone (TYL 5/07; Fig. 3). This layer is under lai n by grey claystone and overlai n by dark-grey mudstone. The highest clus ter con sists of eight thin lay ers of lami - nated lime stone al ter nat ing with non-lam i nated lime stones, mudstones, shales and sandstone (Figs. 2 and 3). Lam i na tion in the two low est limeston e lay ers of this clus ter (TYL 7/07 and TYL 8/07; Fig. 3) is poorly discern ibl e mesoscopically and has a darker hue than the higher lay ers.

DETAILS OF THE RUDAWKA RYMANOWSKA SECTION

The sec tion with the Tylawa Limestones at Rudawka Rymanowska is sit u ated in the Iwonicz Zdrój anticline in the southern (inner) zone of the Silesian Unit in the east ern part of Fig. 2. Lithological colum n of the Tylawa Limestones at Tylawa the Polish Outer Carpathians, ca. 25 km SE from Krosno, in the as logged in 2007 with po si tion of samples referred to in this paper The Tylawa Limestones – a regional marker horizon in the Lower Oligocene of the Paratethys: diagnostic characteristics from the type area 837 a w a l y T

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Wisłok River bed (Fig. 1). The Tylawa Limestones are ex posed there twice, dis placed by a longi tu di nal fault, in expo sures sep- arat ed by ca. 750 m, in a gently dipping se quence of the Menilite Beds. The num ber and qualit y of the expo sures at Rudawka Rymanowska vary through time as a result of floods and hu man in ter ven tion (see Ślączka, 1973b; Haczewski, 1989; Ślączka and Kaminski, 1998; Bieńkowska, 2004; Ciurej, 2009). The limestone s in both groups of expo sures occur ca. 20 m above the top of the Cergowa Sandstone s, in a suc ces - sion of dark, non-calcar e ous organic -rich shale with cherts and lime stones of Dynów Marl-type. Haczewski (1989) corre lat ed laminae in the Tylawa Limestone s on both sides of the fault and demon strated that at least some layers of the dark shale are dis- con tin u ous lat er ally and that centimetric se quences of lami - nated limestone s dis appear over a distanc e of only 750 m. Bieńkowska (2004) studied the fish fauna from three loca ti ons at Rudawka Rymanowska, on both sides of the fault. The de scripti on below is based on the expo sure on the northern side of the fault (arrow in Fig. 1D: N49°31’11.4”, E21°55’50.9”). A nearly com plete secti on was survey ed, 18.6 m long (Fig. 4). The secti on include s 18 layers of the Tylawa Limestone s with a total thickness of 38.7 cm. Seven of these are thinner than 1 cm and the thickest is 5.5 cm thick. Most lay ers are clearly dis tin guish able mesoscopically among the host depos it s; only the thinnest lay ers, consis ting of few lamina cou plets, are less dis tinct (Fig. 5). The char ac ter is tics of lam i na tion are sim i lar to those at Tylawa. Thin in ter ca la tions within the lam i nated lime stone lay ers are simi lar to those at Tylawa but more num erous. They in - clude laminae of mudstone, claystone and micritic limeston e. Some lam i nated lime stone lay ers un der lain by black mudstone have grad ual tran sitions at their base, via the ap pear ance of in - divid ual white laminae which increa se upwards in thickness and densit y (RR 1/07, RR 9/06, RR 6A, RR 5/06; Fig. 5). Some limestone lay ers overlai n by sandstone s dis play, at their tops, struc tures at trib ut able to ero sion dur ing sand de po si tion (RR 2/07 and RR 8/06; Fig. 5).

HOST DEPOSITS OF THE TYLAWA LIMESTONES AT TYLAWA AND RUDAWKA RYMANOWSKA

The lay ers of the Tylawa Lime stones are in ter ca lated with vari ous depos it s that change along the secti ons (Figs. 2–5). These include : thin- and medium -bedded grey, micaceous, cal - care ous sandstone s, which may be very fine-grained and fine-grained, less frequentl y medium -grained. The sandstone lay ers dis play hor i zon tal, wavy, and cross-lam i na tion, rarely con vo luted lam i na tion, cor re spond ing to Tc–d Bouma di vi sions. The shales in this secti on are grey, rarely dark brown, marly. Non-lam i nated lime stones of Dynów Marl-type (limeston e is the main lithol ogy of the lithostratigraphic unit descri bed as the Dynów Marls by Kotlarczyk and Leśniak, 1990) are present in Fig. 4. Lithological colum n of the Tylawa Limestones this sec tion as micritic and marly limestone s, of yellow or at Rudawka Rymanowska as logged in 2006 and 2007 brown hue and grey bands on freshly broken surface s. Cur - with po si tion of samples referred to in this paper rent-lam i na tion and gra da tion, vis i ble as grad ual col our Ex pla na tions as in Fig ure 2 change, are lo cally pres ent in the limestones. Centim etre-scale si lici fied zones are pres ent within the limeston es at some levels in the form of lenses, nodes, di ago nal veins and meshworks. The Tylawa Limestones – a regional marker horizon in the Lower Oligocene of the Paratethys: diagnostic characteristics from the type area 839 a k s w o n a m y R

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Fig. 6. Thin sec tions of Tylawa Limestones from Tylawa A, B – lower clus ter (TYL 3/07); C, D – middle cluster (TYL 5/07); E, F, G – upper cluster (TYL 9A/07). Thick light laminae com posed of coccolithophores (Fig. 7) are sepa rated by thin ner dark laminae, com posed of detri tal mate rial (Fig. 8). All laminae are later ally con tin u ous and have undulose boundari es. Distinct pelletal struc tures com posed of coccolithophores are present in all light laminae. Their size, shapes, and distri bution vary within in di vid ual laminae. Op ti cal mi cro scope: 1N – plane po lar ized lightl, XN – crossed polars. X,Y, Z – posi tion of light laminae and pellets enlar ged in Fig ure 7 842 Agnieszka Ciurej and Grzegorz Haczewski

On weath ered sur faces the lime stones are char ac ter is ti cally MICROSCOPIC CHARACTERISTICS whitish to light-grey. The Dynów Marl-type limeston e lay ers OF THE TYLAWA LIMESTONES are from a few milli metres to a few tens of centi metres thick. Their boundari es with the encom passing depos it s are sharp and When exam ined in thin sec tion using an opti cal micro - disti nct. The secti on studied include s also black and scope, the Tylawa Limeston es dis play very thin lami na tion dark-brown cherts up to 20 cm thick and grey, black, less fre- com posed of alter nating light and dark laminae (Fig. 6). The quently green and grey-green marly and carbon ate -free light laminae, 20–300 mm, excep ti onall y up to 600 mm, in claystones and mudstones. thick ness, have a structure de scribed as micronodular lami -

Fig. 7. SEM–CCI im ages from thin sec tions, show ing coccolithophore rem ains in light laminae in var i ous states of pres erva tion A – mas sive ac cu mu la tion of well-pre served coccospheres; B, C, D – var i ous frag mented coccospheres and coccoliths. Note the minimal al teration by dis - solu tion, overgrowt h or com paction; signs of advanced diagenesis are seen only lo cally (lower right of D); E – as so ci a tion of var i ous frag ments of coccoliths and intact coccospheres (upper right part) within laminae. Alteration by disso lu tion, overgrowt h or com paction is seen only locall y (lower and middle part). Arrows in C and E mark boundari es of pellets . Posi tions of A, B, C shown in Figure 6A: X – C, Y – B, Z – A. D – sam ple TYL 8/07; E – sam ple TYL 9B/07 The Tylawa Limestones – a regional marker horizon in the Lower Oligocene of the Paratethys: diagnostic characteristics from the type area 843

A B Tm P Tm Tm Tm W Tm P P P Tm P P Tm Tm P P Tm Tm Tm

Tm

Fig. 8. SEM–BSE im ages from thin sections, show ing compo nents within dark laminae A – as so ci ation of var i ous amounts of de trital mate rial (clay min erals, quartz, feld spars), py rite, carbon ate grains and or ganic matter; note the dif fer ence in size of detri tal mate rial; B – pre domi nance of py rite and fin est de trital mate rial (clay min erals, quartz, feld spars); Tm – de trital mate rial (clay min erals, quartz, feld spars); P – pyrit e; W – car bonate grains; outlines – organic matter . A – sam ple TYL 8/07; B – sam ple TYL 9B/07 nated (Haczewski, 1989), with ovoidal pel lets, av er ag ing 50 x and organic matter (Fig. 8). Ghosts of pennate di atom s are pres- 150 mm in size, ar ranged in hor izon tal laminae. The pellets are ent as deform ed voids and indis ti nct im prints (see Ciurej, 2009). in ter preted as fae cal pel lets of zoo plank ton (see Haczewski, 1989; Ciurej, 2009). The laminae differ in pellet size, shape and pack ing. These dif fer ences re sult in fluc tu at ing thick nesses of CONCLUSIONS the laminae and in the nature of their boundari es – more or less undulose, and more or less sharp. Iden ti fi ca tion of the Tylawa Limestone s on the grounds of Anal ysis by SEM, in CCI mode, re vealed that coccolitho- their mesoscopic li thol ogy may be problem atic becaus e of vari - phore skel etons are the main com ponent of the light laminae a tion in contra st and colour of laminae. Mi cro scopic ex am i na- (Fig. 7). Nearly all the coccolithophore skel e tal ma te rial is tion by opti cal micro scope and SEM provides more lithological packed in pel lets. The cal car eous nannofossils are rep re sented and micropaleontological di ag nos tic cri te ria that may be sum - by a low-di ver sity as sem blage dom i nated by Reticulofenestra marized as follows: ornata Müller (see Ciurej, 2009). Preser va ti on of the cocco - – ab sence of foraminifers, lithophore mate ria l is very good in most of the laminae studied. – mass oc cur rences of Reticulofenestra ornata Müller, There is lit tle in di ca tion of dis so lu tion or sec ond ary over- – voids after pennate dia tom s, growth and of me chan i cal frag men ta tion by com pac tion. A – dark laminae that are more disti nct and indi vid ual in strik ingly large part of the cocccolithophore mate rial is pre - nature than in the Jasło Limestone . served as in tact coccospheres (Fig. 7A). The scarce matrix in the light laminae con sists of clay miner als, car bon ate grains, Ac knowl edge ments. This study was partly fi nanced by the py rite and or ganic matter and it is pres ent within pel lets as well Min is try of Sci ence and Higher Ed u ca tion (MNiSW) grant as be tween them. 18.18.140.652 to GH and by the Na tional Sci ence Cen tre The typi cal dark laminae are thinner than the light ones, be- (NCN) grant 2011/01/D/ST10/04617 to AC. The micro scopi c tween 3 and 30 mm in most cases, excep ti onall y up to 100 mm study was done by AC within a PhD pro ject super vise d by GH. (Fig. 6). About half of the dark laminae are thinner than 10 mm. The genera l desc ript ion and int erpre t ati on has been written by Anal ysis of the laminae by SEM using BSE mode reveals that both author s. We appre c iat e helpf ul re views by M. Melinte- they are composed of clay miner als (most likely kaolinite and Do brinescu and H. M. Schulz and the revi sion of the Engli sh illite), quartz, feld spars, car bon ate min er als (cal cite, an ker ite, text by J. Zalasiewicz.. sid er ite, and do lo mite), py rite, phos pho rus de bris (fish de bris) 844 Agnieszka Ciurej and Grzegorz Haczewski

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