GEOWGICA BALCANICA, 25. S-6, Sofia, Decemb. 1995, p. 33-42

New data on the stratigraphy of the Tethyan Triassic in the Strandzha Mts., SE

Sava Savov, Christo Dabovski, Kiril Budurov

Geological Institute, Bulgarian Academy of Sciences, 11JJ Sofw

(submined 20.11.1995; accepted for publication 27.11.1995)

C. CatiOfl, X. ,[Ja6otlc1Cu, K. Iiydypoe -HoeNe c>aHH&Ie o cmpamuzpatjjuu Temucc1eozo mpuaca­ CmpaHc>xaHciCue zpp~>~ (IOzo-Bocmo'IHu IiruzapUR). )J,aHHble aaropoa H ony6nHJ:oaaHHU HHcllop­ MaUHll JliUOT OCHoilaHHe JlJlll HOBOro aH8JJH3a CTpaTHfPa41HH TpHaCCOBbiX DOpO.Il B CTpaH.QaaHCJ:HX ropax. TpHaC OTHeceH J:aTeropH'IeCJ:H J: TCTHCCJ:OMY THny. 3oH8JlbHOC CTpaTHci»HUHpOBI\HHe TpHaca DO J:OHO.IlOHTHOii 4layHe H peJ:OHCTpYJ:UHll TpHaCOBOro pa3pe3a, C.QenaJJH ero CODOCTaBHI\IIbll\11 C .Qpy­ J"HMH pa3pC3aMH Ha TeppHTOpHH lionrapHH. MHoro'tacneHHble nHTOCTpaTHrpa41H'feCJ:He e.QHHHUbl, Bbi.QeneHHble Ha OCHOBaHHH p&lHOCTeneHHOii MeTaMOpci»H'feCJ:Oil H TCJ:TOHH'feCJ:Oii o6pa6oTJ:H 00- po.Q, o61.e.QHHeHbl B 'ICTblpe CBHTbl. CTpbiBHHUCJ:U CBHTa cnaraeT HH3bl pa3pC3a. 0Ha npe.QCTIUIJJeHa MCT&rpaBIIJIHTaMH H MeTancaMHTaMH C npocnoiiJ:aMH MenJ:OraJJe'IHbiX J:OHrnOMepaTOB. B cne.QyJO­ IQeii, 3a6epCKOI CBHTe, Bbi.QeneHbl .ll&a 'tneHa: rpaMaTHitOBCKHI H KaJHiiCKH.IlOnCJ:Hii. 3-fa CBHTa cno­ aeHa cllnHWeOO.QOOHO 'tepe.ll)'JOIUHMHCll aprHMHTaMH, tlliiJinHTaMH, MCTaaneaponHTaMH, MCTanca­ MHTaMH, H MpaMOpH30BaHHbii\IIH HlBCCTHliJ:aMH, a T&J:ae aynJ:aHHTaMH OCHOBHOrO COCTaBa H PYAHbi­ MH TenaMH. 3a6epCJ:all CBHTa OXBaTbiBaCT BepXHHi COaT H HH3bl 3reiiCJ:Oro DOAbllpyca (aHH3HHCJ:Hil llpyc). B cpeAHHX OTAenax pa3pC3a pacnonoaeHa KOHAOnOBCICU CBHTa, cnoaeHHU H3BeCTHliiCaMH H MpaMOpH30BaHHbiMH H3BeC"!llllltaMH. Ee OXBaT: nen&COHCKHI H HMHpHICJ:Hil DOAbllpycbl aHH3HICJ:O­ ro llpyca, cllaccaHCJCHil llpyc H HHaHHe-cpe.QHHe OTAenbl nOHrOOap.QCitOJ"O DOAbllpyca (na.QHHCKHI llpyC). BepXHHe 'faCTH pa3pe3a npe.QCTaaneHbl JIHDa'IKOI CBHTOii . 3-fo tllnHWeOOAOOHOe 'tepe.QOBaHHe H3BeC­ THllltOB, rnHHCTbiX cnaHQeB H neC'faHHJ:OB. 0XBaT CBHTbl - noHro6apACJ:Hii DOAbllpyc na.QHHCJ:OJ"O llpyca- naQJ:Hii DOAbllpyc H 'faCTH anayHCICOJ"O DO.Ilbllpyca (HOpHICJ:Hii 11pyc).

Abstract Data newly obtained by the authors together with already published evidence allow for a new analysis of the Triassic stratigraphy in the Strandzha Mountains. The Triassic in the Strandzha Mountains is referred with certainty to the Tethyan type of evolution. Its zonal stratigraphy is being detailized on the basis of conodont fauna, and the section is reconstructed and correlated with the other sections in Bulgaria. The numerous lithostratigraphic units already introduced have been created mainly due to secondary features as different degree of metamorphism and of tectonic reworking. They are now generalized into four formal units (Formations), and namely (from bottom to top): the basal Stravnitsa Formation built up of metagravelites, metapsammites and interbedded line-pebble conglom­ erates; the Zaberska Formation (with two members, Gramatikovo and Kaziyskidol Members, respec­ tively), built up of nyschoid alternation of shales, phyllites, metasiltstones, metapsammites, and marmorized limestones as well as of basic volcanics and ore bodies, within the age range from upper parts of the Spathian to lowermost parts of the Aegean Substage of the Anisian Stage; Formation built up of limestones and marmorized limestones, with Anisian (Pelsonian and lllyrian Substages) and Ladinian (Fassanian and lower and middle parts of the Longobardian Substage) age; and (at the top) the Lipatka Formation built up of flyschoid interbedding of limestones, slates and sandstones within the range upper parts of the Ladinian (Upper Longobardian Substage) - Norian (Lacian and parts of the Alaunian Substage).

3 Geologica Balcanica, 25, 5-6 33 Introduction

During the last t~o decades, as a result of the detailed and pioneer studies of S. S a v o v and G. C a t a I o v, considerable progress has been made in the lithostratigraphic subdivision and dl!ting of the low-grade metamorphic roc~s in Bulgarian ~trandzha. The studies of Catalqv, published in a s~ries of papers (C a t­ a I o v in Cat a I o v, B u d u r o v, 1975; C a t a I o v, 1980; Cat a 1 o v, 1983, q a­ T a JJ o 8, 1985) and in his fundamental summarising work (q a T a JJ o 8,., 1990) laid the grounds of Triassic lithostt:,atigraphy in Strandzha. . Joint studies by Catalov and Budurov (Sa v o vet al., 1971; Cat a I o v et al., 1972; Cat a I o v, Bud u r o v, 1975, 1978, 1985; B u d u r o v, C a t a I o v, 1978) determined the age of the lithostratigraphic units on the basis of conodonts identified by Budurov. Later, Budurov (in B u d u r o v, T r i f o n ova, 1991) supplemented and systematized these data. All these studies form n9w a soun.d basis for correlations and reconstructions of Triassic sequences. Catalov (C a t a I o v et al., 1972) was the first author to recognise the allochthonous position of the low-grade metamorphic Triassic in Strandzha. He pointed out some differences with respect to the Triassic in Mts and proposed, in our opinion not quite successfully, the name Strandzha type Triassic. There is no doubt that this type is lithologically very similar to the Alpine, in principle Tethyan Triassic. Catalov (C a t a I o v, 1980; q a T a JJ o 8, I990, p. 35) adopted five criteria to define his three facial types of Triassic - Balkanide, Strandzha and Sakar type. In· our opinion only two of them - facies composition and presence or absence of magmatic rocks - are definitive. The other three criteria - content of fossil fauna and flora, thickness and grade of regional metamorphism, can not be used to divide facial types. In this paper we distinguish two types of Triassic. The allochthonous low­ grade metamorphic Triassic in Strandzha is described as Tethyan type Triassic on the basis of the rock facies. The authochthonous Balkanide Triassic (G an e v, 1974) is referred to as Peri-Tethyan Triassic. The lithostratigraphic units of the Tethyan type Triassic in Strandzha are com­ ponents of the Group. qaT a JJ o 8 (1990) subdivided this group into two subgroups: Grahilov (lower parts) and Bosna (upper parts), and defined nine lithostratigraphic units in them. However, the relations between the two subgroups ~ shown by q a T a JJ o 8 ( 1990, figs . I 0, II) as formational transitions from one subgroup to the other, make the use of the two names inconsistent. In this paper only Veleka Group is assumed to be a valid name. The revised lithostratigraphic units described in this paper are an integral part of a complex thrust belt. This is the reason for a "varied" geological pattern in which the units occur as inpersistent layers and lenses, commonly with obscure geological interrelations. The notions "top" and "bottom" based only on lithostratigraphic rela­ tions are in most cases arbitrary. A more reliable age identification of the formations by means of conodont-dated stratigraphic horizons can resolve some of these problems.

Revised lithostratigraphic units Veleka Group Stravnitsa Formation. Created by Catalov (1983), later described in more detail by qaTaJJ08 (I985, I990). Exposed in the basal parts of the Triassic section (Fig. I). Comprises grey, whitish or 34 greenish metagravellites and metapsammites with coarse cross-bedding and rare interbeds of fine conglomerates, locally quartz-sericite schists, phyllitoid argillites and keratophyres. The rocks rest transgressively on granitoid basement. They are overlain with indistinct contacts by the rocks of Zaberska Formation. The age of the Stravnitsa Formation is older than that of Zaberska Formation, parts of which were dated as upper parts of the Spathian Stage. Thickness - several tens of meters to 150m.

Zaberska Formation Introduced by Catalov (1983). Further details in llaTaJI08 (1985, 1990). Its full synonim is Fomation, an idea sugge.sted by llaTaJI08 (1 990, p. 123). The rocks of Gerovo Formation, described by Catalov (1983) and llaTaJI08 (1985, 1990) are understood here as a repetition of the upper parts of the section of Zaberska Formation. This concept is based on conodont finds of Neospathodus triangularis-Neospathodus homeri A.-z which prove Upper Spathian age (Budurov in Sa v o v et al., 1971; Bud u r o v in Bud u r o v, Cat a I o v, 1978; Budurov in C a t a I o v, B u d u r o v, 1985) . Additional characteristics. Zaberska Formation forms the lower parts of the Tri­ assic section in Strandzha Mountain. It is an interbedding of metaargillites, phyllites, calcareous phyllites, metasiltstones, metaarenites, lenses of marbles and marbleised limestones, rare basic and acid volcanics (diabases and keratophyres). The initial rocks prior to th.e tectonic .and metamorphic events were evidently a flysch-like interbedding of snales, siltstones and sandstones with limestones beds of different thickness. Two members may be divided in the ~berska Formation. The first one is the Gramatikovo Member, defined formerly by Cat a I o v (1 983; qaT a JI o 8, 1985) as Gramatikovo Formation. It occurs in the upper parts of the Zaberska Formation and comprises calcite phyllites and marbles intersected by diabase bodies. The age of this member is Upper Spath ian- Lower Anisian (Aegean) based on finds of Kashmirella gondolelloides R.-Z. The thickness in the type area is about 600 m. The second member, Kaziyskidol Member (Ka:3HHCKHAOJICKH •men), is intro­ duced here for the first time. It was identified in the course of field work on the geological map of Bulgaria on the scale 1:100 000. The member comprises mainly grey-black, weakly marbleised limestones interbedded locally with slates, calcareous phyllites and metasiltstones. No data on synchronous basic or acid volcanism are available. A detailed description of this member is given later in this paper. The rocks of Zaberska Formation overlie with indistinct contact the rocks of Stravnitsa Formation. Its upper boundary is tectonic. The thickness is below 2000 m. Notes. In the past Budurov (in S a v o v et al., 1971) defined Griesbach ian age on the basis of Jsarcicella iserica (Huckriede) in some rocks of this formation. The find was not confirmed by later studies (Budurov in B u d u r o v, T r i f o n ova, 1991) and thus we accept this determination as inconsistent. ·

Kondolovo Formation

Introduced by Cat a I o v, (1983; qaT a JI o 8 1985) as indicated in 4 a-r a JI o 8 (1990, p. 135). Kondolovo Formation comprises grey-white, grey to dark grey thick­ bedded to massive limestones, marbled and re-crystallized limestones which in places alternate with packets of fine to medium-bedded silty-clayey nodular microgranular and biodetrital limestones. Conodont fauna determined by Budurov (Budurov in

35 ~ LITHOLOGY MEMBER CONODONT ZONES < ~

- z I I I ------< I I II Epigondolella pastera R.-Z. -~ 0 I Jl _l z u l _l Metapolygnathus abneptis A.-z. Jl _l _l I I u _l l l J Paragondo/ella nodosa R.-Z. ~ l JL l z u l l ~ < :3 z- I _l _l Paragondolella ~ u I II < polygnathiformis A.-Z. u I u I I l _l ll l _l l Jl _l I Paragondole//a foliata R.-Z. z l l l < I I 1 I _l _l Sephardie/la mungoensis A.-Z. -z I I _l -0 I _l _l < I I I ...:I I I I §2 Pridaella constricta A.-Z. I I I 0 I l l ..:I 1--- I I J 8 I I I a Pridaella cornuta R.-z. I I _l ~ z I I I < I I I Paragondolella bifurcata 1-Z. en I I I - I I I z- I I I Paragondolella bulgarica R.-Z. < I I I '""I I N'"'"' I"' Kashmirel/a gondolelloides R.-Z. "- """ Gram a- "' ~ "' p:fT Kaziyski {/}~ ..... t= ~ tikovo Neaspathodus triangularis - z """" ""' "" 1:<1 < al dol Neospathodus homeri A.-Z. ;:s -:z:: '"'" "' ------f-o f' < "" ll.. - en >< r-?- ~~ +++ + + ++ ~

36 Cat a 1 o v, Bud u r o v, 1975, 1978; Budurov in B u d u r o v, C a t a 1 o v, 1978) prove the following conodont zones: Paragondolella bulgarica R.-Z.,Paragondolella bifurcata 1.-Z., Pridaella cornuta R.-Z., Pridaella constricta A.-Z., Sephardiella mungoensis A.-Z.,Paragondolellafoliata R.-Z. On this basis Budurov defined Anisian (Pelsonian and Illyrian Substages) and Ladinian (Fassanian Substage and lower and middle parts of Longobardian Substage) Age. The lower boundary is tectonic, and the upper one is placed at the base of thin-bedded clayey limestones that rapidly pass upwards by gradual transition into the flysch-like section of Lipacka Formation. The thickness is 350 to 800 m.

LipaCka Formation Introduced by Catalov (Cat a 1o v, Bud u r o v, 1975) and revised later by Catalov (1980; q a T a n o B, 1985). Comprises dark-blue limestones, slates and sandstones that alternate locally to form flys9h-like packets. On the basis of conodon~ deter­ mined by Budurov (Buduroy in C a t a 1 o v et al., 1972; Budurov in C a t a- 1 o v, 1978; Budurov in Catalov, Budurov, 1978, 1985) the conodont zones Paragondolella foliata R.-Z., Paragondolella polygnathiformis A.-Z., Paragondolella nodosa R.-Z., Metapolygnathus abneptis A.-Z. and Epigondolella postera R.-Z. have been determined. Thus, the rocks of the Lipacka formation include the whole unin­ terrupted stratigraphic range from Upper Ladinian (upper parts of the Longobardian Substage) to parts of the Norian (Lacian and Alaunian Substage).

Kaziyskidol Member (KaJHiiCKHAOJICKH 'fJieH), new member of the Zaberska Formation

Nomenclature. The name of the unit is derived from the name of the area ofKaziyski dol, left tributary of the Lopushnitsa River, located south of the village of Kosti, District.

~ schists

marbles metasandstones

diabases and ' ' \ keratophyres , ' metasandstones & .metagravelites

fimestones conglomerates

mramorized limestones granites

F'13. 1. Generalized section of the Tethyan Triassic in the Strandzba Mountains

37 Defining features. The pri ncipal components of the unit are black clayey or phyllitoid slates, calcareous and silty-clayey argillites and dark-grey to black, mainly fine-bedded limestones, re-crystallized to different extent, which form packets or individual bodies. Locally (Kaziyski dol), flysch-like alternation of large packets of clayey and phyllitoid slates with fine-bedded limestones occur. The limestones are commonly intersected by a network of calcite veins. Two main types of metamorphosed clayey and silty-clayey rocks may be dis­ tinguished. The first are with massive schistose texture and the second - banded. The massive clayey rocks are slightly lustrous and show distinct schistose texture. They contain hydromica and small quantity of chlorite, quartz, py[ite, organic mat­ ter and sagenite (these descriptions and those cited below are by Catalov, Explana­ tory note to the Geological Map of Bulgaria, 1:100000, Field sheets , Silistar, Maiko Tarnovo and , in press). The banded texture of the silty-clayey schists is defined by alternating white siltstone bands 2-4 mm thick and dark grey to black hydromica bands 2-3 mm thick. The silty laminae contain mainly quartz, rarely al­ bite. The structure is granoblastic. The hydromica laminae comprise mainly hydromica and few chlorite, organic matter and pyrite. The limestones are fine to medium-bedded, the beds being 1-2 mm to 1-5 em thick. Sometimes they are accumulated in packets 0.5 to 5 m thick or form larger bodies (the area of Uzunbudzhak, Sarpiite). Usually they are re-crystallized to vari­ ous extent. The primary micritic structures contain 10 to 50% pseudospar (0.2-0.1 mm). In rare cases they are strongly re-crystallized with pseudospar up to 60-70% or grade into marbles (pseudospar 90%). Previous usage. Initially the rocks of this member were assumed to be Upper Archean (r. 6 o n 1.1 e B, 1923), Lower Palaeozoic- Diabase-Phyllitoid Formation (D i m i t r o v, 1939, 1946), Upper Jurassic-Tithonian (.SI H HIlle B c K H, 1946; D i m i t r o v, 1958). More recently they have been described as Palaeozoic (H a 1.1 e B, 1972, C e p r e e B a et al., 1979; M a I j a k o v et al., 1982) and Lower Triassic - part of the Stoilovo Formation (ll a T a JI o B, 1985); Gramatikovo Formation (ll a T a JI o B, 1986) and Zaberska Formation (ll aT a JI o B, 1990). In the Explana­ tory note to the field sheets Tsarevo, Silistar, Maiko Tarnovo and Rezovo of the Geological Map of Bulgaria on the scale I: I 00 000 (in press), the rocks in question were divided as an informal lithostratigraphic unit - "formation of silicate schists and marbleised limestones". · Distribution. The unit is exposed only in SE Bulgarian Strandzha Mts. It forms an irregular body which occupies a small area along the left bank of the Rezovo River, parallel to the Bulgarian-Turkish border. It is exposed in the sites ofYankova barchina - Y ankov dol, and Golyam and Malak Keratarski dol. The rocks probably extend to the south of the Resovo River and pass into Turkish territory. Thickness. Due to tectonic reasons, the thickness of the unit can not be accu­ rately defined. It varies from 60 m to several hundreds of meters. Age. Finds of the conodont species Neospathodus triangularis (Bender) and Neospathodus homeri (Bender) prove the Neospathodus triangularis - Nesopathodus homeri A.-Z. that indicates the upper parts of the Spathian stage of the Lower Triassic. Relations. The Kaziyskidol Member overlies with a sharp contact the calcite phyllites of the Gramatikovo Member and most probably is in allochthonous posi­ tion. It is covered transgressively and unconformably by the rocks of the Zelenkovska formation (Cenomanian) along the line Kosti Village, Hodzhanski dol and Sarpiite at the Resovska River. The rocks of the unit are intersected by a small Upper Creta­ ceous pluton in the area of Karieto which forms a narrow contact zone. Relics of a

38 Pliocene alluvial cover occur along the slopes of the Resovo River. A complete sec­ tion, wh ere basement and cover are exposed, has not been observed. The lowermost parts of the member are probably exposed on Turkish territory while the cover, as already mentioned, is transgressive and unconformable. Correlation links. The Kaziyskidol Member has no correlates in Bulgarian Strandzha. There are some similarities to the so- called "Marble formation" in the area of Dervent Heights. The parts of the two lithostratigraphic units that contain fossils indicate analogous age (Lower Triassic). However, the sections show certain lithological differences .:..... carbonate rocks in the Dervent Heights, as compared to those in Strandzha, predominate over silicate phyllites. Eventual links may be searched with parts of the "Kapakli Formation" (A y d i 11, 1974) on the territory of . No faunistic age data for this unit are available.

Description of the type section of the Kaziyskidol Member The section is located in the area ofKaziyski dol, along the stream of the same name which is a northern (left) tributary of the Lopushnitsa River. The length of the sec­ tion is 900 m. Cover - Quaternary alluvial sediments 4-5 m Kaziyskidol Member, exposed at a distance of 60 m. Grey marblized limestones interbedded wit,-. ash·grey calcareous slates 4m Grey marbled limestones, forming a stone ridge 0.4m Calcareous slates 0.6 m Grey marbled limestones, alternating with calcareous slates 2m Grey-black tine-bedded limestones with a network of calcite veinlets lm Sample K-1 in the base Interbedding of grey-black tine-bedded limestones, intersected by calcite veinlets, with phyllitoid rocks, grey-black to ash-grey on weathered surface 3.5 m Grey-black tine-bedded limestones in packets up to 20-30 em. interbedded by calcareous-clayey slates and silty-clayey slates; the latter occur also between the packets 2.5 m Grey-black tine-bedded limestones 3.5 m Sample K-2 0.5 m. from the base Sample K-3 from the top Grey-black tine-bedded limestones, forming a packet 2m Sample K-4 in the base Limestones, grey-black, apparently more marblized, tine-bedded, interbedded by thin (2 mm to 3 em) layers of argillites, in the upper part form a stone ridge 0.3 m thick 14m Sample K-5 from the middle of the stone ridge Interbedding of grey limestones with grey-black tine-bedded limestones 4.5 m Sample K-6 at 30 em. from the base, from the grey limestones Limestones, grey-black, intersected by a network of calcite veinlets, forming a stone ridge 4m Fine-bedded grey-black limestones with a network of calcite veins 5.5 m Dark-grey limestones, fine-bedded, strongly re-crystallised 3m Sample K-7 from the top Limestones, tine-bedded, grey-black, forming in the base a 4 m stone ridge 6m Sample K-8 in the bas Limestones, grey-black, fine-bedded, forming packets, cut .by a diorite-porphyrite dike 4m Sample K-9 at 2 m. from the base A stone ridge of dark-grey to black tine-bedded limestones

39 forming packets 6m Sample K-10 at 5 m from the base Basement not observed since the rocks are covered by the terrace of Lopushnitsa River

Additional section of Kaziyskidol Member in the area of Yankov dol The section is located in the area of Yankov dol along the stream which is a northern tributary of Rezovska River. Cover- Quaternary alluvial sediments Kaziyskidol Member (new member) exposed at 83 m without top and bottom observed Limestones, thin-bedded, grey-black with calcite network, forming packets 4m Sample K-11 at I m. from base Limestones, fine-bedded, grey-black, forming packets, with thin 1-2 mm silty-clayey slates between the beds 5m Limestones, grey-black, fine-bedded, intersected by a chaotic network of calcite vein lets commonly with silty-clayey slates between the beds forming packets 0.5-0_8 m 6m Sample K-12 from the base Interbedding of grey-black limestones forming packets, with grey-black argillites and calcareous-clayey slates; argillites and slates I ,2 mm thick occur also between limestone beds 12m Interbedding of grey-black fine-bedded limestones, intersected by calcite vein lets, with beds and layers of phyllitoid slates up to I m. thick; general increase of phyllitoid slates 6m Limestones, fine-bedded, grey-black, forming a stone ridge, intersected by calcite veinlets 3m No exposures 20m Grey to silver-grey clayey phyllitoid and phyllitoid slates 3m No exposures 20m Phyllitoid slates, grey, interbedded by fine-bedded grey-black limestones 4m Sample K-13 at I m from base Soil, no base exposed

Additional section of Kaziyskidol Member in the area of Uzunbudzhak The section is exposed in the southernmost parts of the area of Uzunbudzhak, south of Kosti Village, Burgas District, in close proximity to Rezovo River along its the steep slope. Cover - Quaternary alluvial sediments Kaziyskidol Member (new member)- exposed at a distance of 41 m. The lowermost parts most prob­ ably crop out on Turkish territory. The upper parts are also not exposed. Limestones, fine-bedded, considerably marbleised, cut by numerous calcite veinlets. They occur in solid packets which form stone ridges 0.5-1.2 m thick 32 m Marbled limestones and marbles, light grey to grey, thick bedded. 9 m

40 Conclusions

The following conclusions may be drawn on the basis of t~e so far conducted studies. I. The Triassic in the Strandzha Mts is of Tethyan (Alpine) type. 2.The section of the Tethyan Triassic in Strandzha comprises four lithostratigraphic units, and namely: · Basal unit (Stravnitsa Formation), formed of metagravellites and metapsammites with cross-stratification, interbeds of fine conglomerates and rare keratophyre bodies. This indicates that the initial rocks in the base of the Triassic section were arcose sandstones and conglomerates. · Lower unit (Zaberska Formation), comprising an interbedding of slates, phyllites, metasiltstones, metaarenites with beds of marbles and marbleised limestones as well as basic and acid volcanics. The initial rocks were clayey, calcareous-clayey, sandy and limestone rocks. In many locations the rocks form flysch-like interbedding (lower flysch-like unit in the Triassic section of Strandzha). Two members may be divided locally: Gramatikovo Member with predominating calcite phyllites and marbles, and Kaziyskidol Member (new member) -a flysch-like sequence but comprising large limestone bodies in the top parts. The age of some parts of the unit ranges over the upper parts of the Spathian- lowermost parts of the Aegean Substage of the Anisian. · Limestone unit in the middle of the section (Kondolovo Formation).The age is Anisiao (Pelsonian and Illyrian Substage) - Ladinian (Fassanian and Longobardi an Substage). · Flysch-like unit in the upper part of the Triassic section (Lipacka Formation) comprising limestones, slates and sandstones. The age of this unit ranges from the lower parts of Ladinian (Upper Longobardian Substage) to the Norian (Lacian and parts of the Allaunian Substage) Stage. 3. Of the so far interpreted fossil remains of bivalves, brachiopods, crinoids, echinides, green algae, foraminifers and conodonts, only conodonts may be used to create a reliable zonal stratigraphy as a basis for dating, reconstructions and corre­ lations of the Triassic in the Strandzha Mts. 4. The complex geological structure of the Triassic sequences in Strandzha is a result of thrust tectonics. Future studies will show whether the Triassic in East Stara Planina which occurs as olistolites and likewise exhibits a complex geological structure, could be in a similar allochthonous position as the Triassic in Strandzha. 5. The Griesbach ian Stage of the Triassic, adopted for some horizons on the basis of a single conodont find in the past, was not confirmed by later studies. Most probably these conodonts were introduced as a mechanical contamination during the processing of the samples.

References

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