GEOLOGICA BALCANICA, 25. 3-4, Sofia, August. 1995, p. 3-26
Upper Cretaceous stratigraphy of the Eastern Sredna Gora Zone
Ivan Nachev, Ekaterina Dimitrova
Geologica/Institute, Bulgarian Academy of Sciences. 1113-Sqfia
Submilled 30. 06. 1994; accepted for publication 24. OJ. 1995
H.. K. H a 'I e B a, E . .[{ H M H T p o B a - CTpaTHrpaljlHR sepxHero Mena B BocTo'IHOM Cpe.llHoropbe. JlHTOCTpaTHrpaljiH'IeCKaR cxeMa BKJJJO'!aeT Kap.llHljiCKYJO (ceHoMaH), I..(epoBCKYJO (ceaoMaH. rypoa), fpa.llHWCKYIO (KOHbRK- KaMnaH), Ky6a.QHHCKYIO (KOHbRK -KaMnaH), CHHeMopeUKYJO (KOHbRK- KaM naH), H.3rpescKyJO (KOHbliK - KaMnaH), fnywHHKCKYIO (KaMnaa), KoHbOBCKYIO (KaMnaH) H .[{pRHKO seuKYJO (MaaCTpHXT) CBHTbl. XpOHOCTpaTHrpaljiHR OCHOBaHa Ha MHKpoljlayHHCTH'IeCKHX (ljlopaMHHH ljlepOBbiX) coo6mecTBax. CeHoMaH npe.QcTaBJJeH JJHMHH'!ecKaMH H yrneHOCHbiMH, TO'IHO He.QaTHpo BaHHbiMH (Kap.QHljiCKaR CBHTa), HJIH MeJJKOBO.IlHbiMH .llaTHpOBaHHbiMH KJJaCTH'IeCKHMH nopO.IlaMH H H3BeCTHRKaMH (I..(epKOBCKall CBHTa). TypoH BKJIIO'IaeT BepXHHe CJIOH MeJJKOBO.IlHbiX nopO.Il (I..(epOBCKaR CBHTa). KoHbRK npe.llcTaBJJeH rny6oKOBO.IlHbiM rpaysaKKO - anespoJJHTOBbiM ljiJJHWeM (fpa.llHillCKaR CBHTa), H3BeCTHRKaMH H fJIHHHCTbiMH H3BeCTHRKaMH (Ky6a.QHHCK8R CBHTa), Teljlporyp6H.IlHTOBbiM ljiJJHWeM (CHHeMOpeUKaR CBHTa) H BYJJKaHH'IeCKHMH ryljlaMH (H.3rpeBCKall CBHTa). CaHTOH BKJIIO'!aeT rny6oKOBO.IlHble nopo.Qbl, KOTOpble aHanorH'IHbl nopo.QaM KOHbRKa. KaMnaH npe.llCTaBJJeH rny6oKo BO.IlHbiMH H3BeCTHRKaMH H fJIHHHCTbiMH H3BeCTHRKaMH (BepXHR11 '!aCTb Ky6a.llHHCKOH CBHTbl), Teljlpo ryp6H.QHTOBbiM ljiJJHWeM (CHHeMOpeUKaR CBHTa), H3BeCTHRKaMH H fJIHHHCTbiMH H3BeCTHRKaMH (fJJyW HHKCKaR CBHTa), BYJJKaHH'IeCKHMH ryljlaMH (J.1.3rpeBCKall CBHTa) H KJJaCTH'IHO- H3BeCTHRKOBbiM ljiJJH WeM (KOHbOBCKaR CBHTa) . MaaCTpHXT xapaKTepH3yeTCll MeJJKOBO.IlHbiMH H3BeCTHRKaMH, neC'IaHHKH MH H aJJeBpOJJHTaMH (.[{pRHKOBeUKaR CBHTa). Ce.QHMeHTaUHOHHble o6cTaHOBKH MeHRJJHCb TeMnopanbHo: JJHMHH'IeCKaR (ceHoMaH?); MeJJKoe JnHKOHTHHeHTaJJbHoe Mope (MaacTpHXT). PaHHHe cy6repUHHCKHe .llBHlKeHHR ocymecTBHJJHCb B OTpe3- Ke MelK.IlY TypOHOM H KOHbRKOM. no3.QHHH cy6repUHHCKHH oporeHe3 npORBHJICll B CKJJa.ll'laTOCTH ITOC· JJe KaMnaHa H .llO MaCTpHXTa. Abstract. The litostratigraphic subdivision includes the Kardif (Cenomanian?), Cerovska (Cenomanian, Turonian), Gradiste (Coniacian, Santonian), Kubadin (Coniacian-Campanian), Sinemorec (Coniacian-Campanian), Izgrev (Coniacian-Campanian), Glusnik (Campanian), Konjovo (Campanian) and Dryankovec (Maastrichtian) Formations. The chronostratigraphy is based on microfaunistic (foraminifers) associations. The Cenomanian consists of limnic and coal-bearing undated rocks (Kardif Formation) or of shallow-marine dated clas tic rocks and limestones (Cerovska Formation). The Turonian includes the upper part of the shallow water rocks (Cerovska Formation). The Coniacian is represented by deep-marine graywacke-silstone flysch (Gradiste Formation), limestones and arillaceous limestones (Kubadin Formation), tephroturbidite flysch (Sinemorec Formation) and volcanic tufTs (lzgrev Formation). The Santonian includes deep marine rocks, which are similar to these of the Coniacian. The Campanian is represented by deep marine limestones and argillaceous limestones (the upper part of Kubadin Formation), tephroturbidite flysch (Sinemorec Formation), limestones and argillaceous limestones (Giusnik Formation), volcanic tufTs (Izgrev Formation) and clastic-limestone flysch (Konjovo Formation). The Maastrichtian is char acterized by shallow-marine limestones, sandstones and siltstones (Dryankovec Formation). The sedimentary environments had changed temporally: limnic (Cenomanian?); shallow epicon tinental sea (Cenomanian, Turonian); deep-marine Sredna Gora intra-arc trough (Coniacian-Campanian); superimposed shallow epicontinental sea (Maastrichtian). The Early Subhercynian orogenic movements had occured between the Turonian and the Coniacian. The Late Subhercynian orogeny have caused a folding after the Campanian, but before the Maastrichtian.
3 Introduction The Upper Cretaceous stratigraphy in the Eastern Sredna Gora zone is based mainly on the results of the systematical field description and sampling of the sections as well as on the laboratory micropaleontological studies of about 600 samples. The sampling, the compilation of the map and the sections as well as most of the manu script belong to I. N a c h e v. The determination of the microfossil associations, as well as the text with the analysis and interpretation of the microfaunistic assem blages belong to E. D i m i t r o v a. The characteristic macrofossils are cited after published evidence. In the article are discussed the problems of the Upper Cretaceous litho- and chronostratigraphy in the Eastern Sredna Gora zone. The Upper Cretaceous stratig raphy after microfaunistic associations is published for the first time in this paper.
Previous studies The evolution of the knowledge on the Upper Cretaceous stratigraphy is a long and successionable process. First data on the Upper Cretaceous rocks have been given in several works (3 JI a T a p c K H, 191 0; E o H q e B, 1917; .SI H H w e B c K H, 1946; K o e H, 1946;UaHKOB, 1946; EoH'IeB, 1971). The Upper Cretaceous stratigraphy is worked out in some regional geological works on Southeast Strandza (K y JI a K c 'h 3 o B and al., 1962, 1964), Aytos Moun tain (U a H K o B, K ex a if o B a, 1963) and Southeast Bulgaria (U a H Ko B, 1968; K 'h H 'I e a, 1971; K y JI a K c 'h 3 o B, 1974; H w K o JI o B, 1979). In these works are described Cenomanian, Turonian, Lower and Upper Senonian, Senonian in general or other single stages (Campanian, Maastrichtian). From lithostratigraphic point of view (Fig. 14), "horizons, formations, series and geological formations" or "Forma tions" are distinguished (K y JI a K c 'h 3 o B and al., 1962, 1964: U a H K o B, Kexail:osa, 1963; UaHKOB, 1968; K'hH'IeB, 1971; KyJiaKCb30B, 1974; H w Ko JI o B, 1979; n JI o T H w Ko B a, H a 'I e B, 1987). The detailed lithostratigraphy is subject of two simultaneous studies, but is based on different principles (TIe T p o B a et al., 1980; n o n o a et al., 1980; n e T p o a a, C w M e o H o a, 1989). In Southeastern Strandza "coal and supra-coal horizon" in the Cenomanian and the Turonian and "flysch-like and volcanogenic horizon" in the Senonian are distinguished (K y JI a K c b 3 o B et al., 1962, 1964). In Southeastern Bulgaria, three "Lower Cenomanian" and three "Upper Turonian" lithostratigraphic units, "Campanian" breccia -conglomerate-sandstone-marls, flysch -like, tuffic, limestone marls and sedimentary-volcanogenic formation as well as Maastrichtian calcareous, flysch-like and flysch formation are indicated. The Papia volcano was assumed in correctly as "Paleogenic" (K y JI a K c b 3 o B, 1974). In the Aytos Stara Planina Mountains (l.J, a H K o B, K ex a if o B a, 1963), the principal lithostratigraphic units are "Maastrichtian" volcanogenic, flysch-like and flysch horizons. In the Sredna Gora tectonic zone, the informal lithostratigraphic units are Cenomanian- conglomerates and sandstones, "coal-bearing geological formation", "marl series", sandstones and limestones, Turonian- "marl series and flysch geo logical formation", Lower Senonian - "calcareous-marly geological formation", Upper Senonian- "volcanogenic-sedimentary geological formation and flysch geo logical formation" (K 'h H 'I e B, 1971 ). In the Eastern Sredna Gora zone there is "Lower Cenomanian conglomerates, calcareous-sandy, siltstone, quartzite-sandstone, and sandy-limestone horizon, Turonian basal conglomerate-sandstone, shale, coal, supra-coal horizons and flysch-
4 like series as well as Maastrichtian basal breccia-conglomerate, tuffic-volcanogenic, marl-limestone with tuffs, volcanogenic and limestone horizons" (U a H K o B and aJ., 1962; Q a H K 0 B, 1968). The coal occurences in Southeastern Bulgaria are Cenomanian in age with basal conglomerate, coal-bearing and supra-coal marly formation (H n K o JI o B, 1979). The cover is from the flysch formation of Turonian age. In the region of Burgas the Upper Cretaceous lithostratigraphy includes "sedi mentary Varsilo Group ~h sandstone, marl, Gradiste and Kukulyat Formations, volcano-sedimentary Grudovo Group, volcanogenic Burgas Group with Dracevo Formation, Kartalkus Formation with Yasna Polyana and Zivislia Members, Zidarovo and Varli Bryag plutons, Ravnogor Formation with Demirkoi, Tiklite, Marinka and Sozopol Members and Rosen pluton, Tankovo, Medovo and Draganovo Forma tion". The cover is from "complex of sedimentary rocks of Campanian and Maastrichtian age (ll e T p o B a et al., 1980). In the Burgas ore region, the Senonian (Senonian-Campanian) volcanic rocks cover flysch -like and olistostrom formations and includes "Kazaldzik Formation with Papia Member of the andesito-basaltic geological formation, Novo Panicerevo Formation with Varli Bryag and Zidarovo Members, Ahtopol, Rosen, Tankovo, Medovo and Draganovo Formations. The cover is built up of the Emine Flysch Formation (ll o n o B et al., 1980). In the coastal part of the Eastern Sredna Gora Zone, the Upper Cretaceous is subdivided to Cerovska Formation (Cenomanian, Turonian), Burgas complex (Coniacian-Campanian) and Dryankovec Formation (Maastrichtian) (ll JI o T H u K o B a, H a 'I e B, 1987). In the Eastern Sredna Gora the Burgas series was renamed to Burgas Group and Micurin Group was introduced with Pismenovo, Dracevo, Tiklitska and Demirkeui Formations", correlating with a volcanogenic complex (ll e T p o B a, C n Me o HoB, 1989). The Upper Cretaceous chronostratigraphy in the Eastern Sredna Gora is still unsufficiently developed. The Cenomanian and the Turonian are relatively well de fined (K y JI a K c b 3 o Bet al., 1962, 1964; U a H K o B, 1968; H n K o JI o B, 1979). The Senonian is described in general (K y JI a K c b 3 o B et al., 1962, 1964), it is subdi vided to Lower and Upper Senonian (K b H 'I e B, 1971) or are indicated only single stages - Campanian and Maastrichtian, with a "lack" of "Lower Senonian" or Coniacian and Santonian (U a H K o B, 1968; K y JI a K c b 3 o B, 1974). The Upper Cretaceous fossils are described mainly in summarizing works (U a H K o B, 1946; 1982; U a H K o B et al., 1981) , The works concerning the Upper Cretaceous have mainly sedimentological, petrological (and volcanological), geotectonical, mineralogical, geochemical, metalogem:tic and paleogeodynamical aspects. They are not subject of this paper.
Stratigraphy The Upper Cretaceous is widespread in the Eastern Sredna Gora Zone (Fig. 1). The Upper Cretaceous rocks are still unsufficiently studied from stratigraphical point of view. The litho- and chronostratigraphy are made on different principles, incom plete and contradictory. It is motivated by the scarcity and incompleteness of the fossil data and the unsystematic study of the microfaunistic associations (U a H K o B, 1946; 1982; U a H K o B et a!., 1981 ). Due to these reasons, the litho- and chronostratigraphy is discussed on the base of relatively few fossils and in single articles (U a H K o a, 1968; K y JI a K c b 3 o a, 1974; neT p o a a et al., 1980; non o a et al., 1980). 5 0\
' I - . SLIVEN ~ ru:\ ~ @tj}J ~~
~ ..
Fig. I Geological map of the Upper Cretaceous in the Eastern Sredna Gora Zone I - Dryankovec Formation (Maastrichtian); 2- intrusive rocks (Coniacian-Campanian); 3- effusive rocks (Coniacian-Campanian); 4- Glusnik Formation (Campanian); 5 - Konjovo Formation (Campanian); 6 - Izgrev Formation (Coniacian-Campanian); 7 - Sinemorec Formation (Coniacian-Campanian); 8 - Kubadin Formation (Coniacian, Santonian); 9- Gradiste Formation (Coniacian, Santonian); I 0- Cerovska For mation (Cenomanian, Turonian); II - Kardif Formation (Cenomanian?). Lithostratigraphy The Upper Cretaceous lithostratigraphy in the Eastern Sredna Gora has been dis cussed on the basis of different principles and in different aspects. The already pro posed lithostratigraphic subdivisions differ essentially. The distinguished informal lithostratigraphic units are "horizons", "formations", "series" and "geological for mations". Recently a tendency has occured to introduce formal lithostratigraphic units groups and formations. On the basis of unmappable petrochemical criteria, "volcanogenic-sedimentary Grudovo Series (Group)" and "Santonian volcanogenic Burgas Series (Group)" are distinguished, the later being into 6 formations and 8 members (IT e T p o B a et a!., 1980). The petrochemical criteria have also been used for the lithostratigraphic subdivision of the Senonian volcanic rocks, with distinction "andesite-basaltic" geological formation with Kazaldzik Formation, "trachyandesite trachybasalt geological formation" with Novo Panicerovo Formation and "K-alka line basaltoid geological formation" with Tankovo, Medovo and Draganovo Forma tions (IT o n o B eta!., 1980). Often these petrochemical "geological formations" and formations consist of intrusive, volcanic and sedimentary rocks, which makes them exclusively complicated and in practice unreal geological bodies. In accordance to the principle classification of the rock types (intrusive, volcanic, and sedimentary) it is advisable to assume and to map the rocks of the different plutons and volcanoes as well as the natural associations of sedimentary rocks as different lithostratigraphic units. The following study represents an attempt to apply a new and motivated lithostratigraphic subdivision (Fig. 2) for the sedimentary rocks of the Upper Creta ceous from the Eastern Sredna Gora Zone. The following units are distinguished and described: Kardif Formation (Cenomanian?), Cerovska Formation (Cenomanian, Turonian), Gradiste Formation (Coniacian, Santonian), Kubadin Formation (Coniacian, Santonian), Sinemorec Formation (Coniacian-Campanian), Izgrev For mation (Coniacian-Campanian), Konjovo Formation (Campanian), Glusnik For mation (Campanian) and Dryankovec Formation (Maastrichtian). The rocks of the Coniacian-Campanian associate with effusive rocks- necks, lava flows and dykes. Toleiitic basalts, calc-alkaline, subalkaline and K-alkaline basalts are dominating. They are connected to central type subaqual volcanoes - Bakadzik, Zidarovo, Varli Bryag, Papia, etc. The intrusive rocks present are gabrro, monzo nites, syenites and granites, forming plutons, sills and dykes. They build up Manastir, Granitovo, Oman, Fakia, Maiko Tarnovo, Gramatikovo, Varsilo, and other plutons in the Strandza linear Zone and the Varli Bryag, Zidarovo, Rosen and Izgrev en. a 6 0 B c KH, 1988) plutons, in the Burgas volcano-plutonic Zone.
Kardif Formation (Kap.D.HQlCKa CBHTa) (new Formation) The name originates from the mine "Strandzanski Kardif', where in 1936 was done an attempt for industrial mining. The other denominations are "coal horizon" in the Cenomanian (K y JI a K c 'h 3 o B, 1962, 1964) or in tQe Turonian (ll. a H Ko s, 1968), "Cenomanian basal conglomerate, coal and supra-coahnarl formation" (H H Ko JI o B, 1979), "Sandstone Formation" (IT e T p o B a et a!., 1980), "coal-bearing geological formation" (K 'h H 'I e B, 1971) and partly Zelenkovska Formation (IT e T p o B a, C H Me o HoB, 1988). In the sedimentologicallitterature, the definition shale-sand stone geocomplex (H a 'I e s, R He B, 1980; H a 'I e B, C y JI T a HoB, 1991) is known. The chracteristic features of the Kardif Formation are related to the cyclic (cyclotems) alternation of conglomerates, sandstones, siltstones and black coals.
7 ~ Cl Lithostra c Column tigraphy m Fossils -VI a TrochaTmJina sp. 0 ~u ~~i§~§~ Dryankovec r-- HaplaphragmoidesCiblcides voltzianus coronata ·r: • • • Formation 'I' Gyroidina globosa - . • ~ Cantusotruncana contusa 1 • • • • • • Globotruncani ta stuarti Cantusotruncana Eomicata j~~-~~~-~~~t~?-rl]tilC: v r 1\ Orbit?ides sp. c v v v v g 'c ..,. ..,. ~ · + o Globotruncana rugosa &. _ ~ 'j" Globotruncanita stuartiformis t v o E .., 1 Globotruncana linneiana c v ~ + ~ Contusotruncana Eornicata u P--r-'-\J-·-"~·r:'::'fri ..... 'lk..._.'"" c: ' ~ ~ o 7vr-~r------~ c: :;: Zg~;+ c v \), \), .~~r g Heterohelicidae ·c e~ v S? 0 v" Hedbergella sp...... v. v. \) & ~ t I ~ v c ""• v. v ~~t ~ VI v 'U )~ + 1-...... oll------t c: II ~~v c ~ ~t ·u . .'\ E)!!+ o Heterohelicidae II V ~ Globotruncana linneiana c c: + I ·c Hedbergella sp. 0 iii ' 7~ ~ u -'\ • o'\ 7~
0 Heterohelicidae 0 M Praeglabotruncana gibba k-i"r-....,"__...,hr-~~r::-:-t C e r o v s k a I Hedbergella sp. ~ ~ • -'!'...., "" Formation
o • o Form at ion 0
lo 0 oh ~2 ~3 b -14 ffis ~6 I! T Jl7 ma I v." ..,.lg 5:5l,o E2:]3,, I+++ 112 Fig. 2. Generalized stratigraphy of the Upper Cretaceous I - Conglomerates, microconglomerates; 2 - graywackes, quartz sandstones; 3 - siltstones; 4 -shales, clays; 5 - sandy limestones; 6 - limestones; 7 - argillaceous limestones; 8 - clastic limestones; 9 - tephraturbidites (tephroid rocks); I 0 - volcanic tuffs; II - effusive rocks; 12 - intrusive rocks.
The coals are found in one up to four beds (H H K o 11 o a, 1979). The uncomplete syclotems consist of sandstones, shales and coals or siltstones and shales. The holostratotype is situated near the mine "Strandzanski Kardir' in the valley of Cerovska River, south of the Krousevec Village (Fig. 1) . Cover: shallow-marine conglomerates, calcareous sandstones and sandy limestones with orbitolines (Cerovska Formation). Transgressive contact.
8 3. Few quartz sandstones and Jots of siltstones and black shales 25m 2. Quartz sandstones, siltstones, black shales and four beds of black coals /0.2, 0.5, 0.7 and 0.3m thick/ 45m I. Polygenic conglomerates, quartz conglomerates, quartzite-like sandstone and thin layers of black shales 30m Basement : flysch from graywackes, siltstones and black shales (fithonianf. The occurence is stripped. The first stripe begins from Kamenec Village and crossing Kamen Vrah reaches up to Stefan Karadzovo Village. The second stripe begins West of the Goliamo Bukovo village. The third stripe begins near Varsilo Village, leaps across Cerovska and Zelenkovska River and reaches up to Vizica Vil lage. The fourth stripe begins near Balgari Village and through Kosti Village goes over the state border (Fig. 1). The thickness varies from 30 up to 50m. The rocks of the Formation lie with a parallel to angular unconformity above Jurassic, Triassic, Paleozoic and Precambrian rocks. Fossils have not been found. Some orbitolins are mentioned, but they probably originate from the above laying Cenomanian rocks. The age of the Formation is considered conditionally as Cenomanian.
Cerovska Formation (U:epoacKa CBHTa) (new Formation) The name originates from Cerovska River, where the stratotype is located. Other denominations are "supra-coal horizon" (K y JI a Kc "h 3 o Bet al., 1962, 1964), "supra coal marl horizon" (U: a H Ko B, 1968), "marl series" (K "h H q e B, 1971), "supra-marl formation" (H H Ko JI o B, 1979) and "Marl Formation" (ll e T p o B a et al., 1980). In the sedimentological literature is described as sandstone-limestone geocomplex (H a 1-le B, j{ H e B, 1980; H a q e B, C y JI T a H 0 B, 1991 ). The chracteristic features of the Cerovska Formation are connected to the pres ence of conglomerates, sandstones, siltstones, shales, argillaceous limestones ("marls") and limestones. Dominating are the calcareous sandstones, the sandy limestones and the biomorphic (hippuritic) limestones. A part of the limestones are recrystal lized or dolomitizited (Fig. 4, 5, 6) The holostratotype is the section Cerovska River (Fig. 3). Cover: flysch consisting of graywackes, siltstones and black shales /Gradiska Formation/. 3. Single beds of calcareous sandstones with glauconite, alternation of calcareous, argillaceous siltstones, black calcareous shales and argillaceous limestones 20m 2. Quartzite-like sandstones in alternation with calcareous sandstones and sandy limestones with orbitolins 70m l. Quartz conglomerates, microconglomerates and quartzite-like sandstones 30m Basement: siltstones in alternation with black shales fK.ardif Formation/. The rocks of the Formation occur in the stripe between the villages ofKamenec, Polyana, Kamen Vrah, Goljamo Bukovo, Varsilo, Vizica, Balgari and Kosti (Fig. 1). The thickness is from 30 up to 300m. The rocks of the Formation lie transgressively over Kardif Formation or over Jurassic, Triassic, Paleozoic and Precambrian rocks. The macrofossils are shallow-water hippurites. The microfossils are mainly ben thonic foraminifers, Orbitolina concava Lamarck, Nezzazata simplex 0 m a r a, Pseudolituonella sp., Miliolidae and Textularidae. The plankcton foraminifers are Rotaliopora cushmani Morrow, Praeglobotruncana sp., Whitheinella sp.,Hedbergella sp., and Heterohelicidae (Fig. 7, 8). The age of the Cerovska Formation is determined as Cenomanian and Turonian, based on microfossil associations.
9 Ill Gl "'Ql C7l Column m Fossils 01 Column Ill Fossils .....t:J 2 Vl Vl
V•
V• v v v v St v 167 v v v v ...,. ...,...... e. o· ~. . "'" V• Cp . U40 v. "' ~ -
0 V• ~ .. _<;: .. v v 360 ..., . Cn .... "'' . "' ..... Heterollel.ic.idoe vHedbeqella "'' "'' •l'.
Heter ohelicidae St 1&0 Globatrvnc&~W. linnei.na 1/ Hedbergella •l'· Cn 60 Heterohelicidae v Hedbergella •P. • 41 Rad.tolaria
Fig. 4. Upper Cretaceous in section Korten Lenticuline sp. Heteroltelicidae Tn 120 Hedbergella sp. ~a
Orb i tol1na canca va Cm 60 Nezzaz:ata simplex Ill Pseudoli tuonelle sp. Fig. 3. Upper Cretaceous in the section Cerovska lfiliolidae River \ 'l'extulariidae I - olistostromes; 2 - conglomerates, microcon glomerates; 3 - graywackes, quartz sandstones· Cm? 100 4- siltstones; 5 -shales, clays; 6 -shales, clays: ...... black coals; 7 - sandy limestones; 8 - argilla - ceous limestones (marls); 9 - limestones; 10 - 1 biodetritic and biomorphic limestones; II - clas tic limestones; 12 - dolomites; 13 - chert rocks; 14 - coarse tephraturbidites; 15 - fine tephraturbidites; 16- volcanic tuffs; 17 - effu sive rocks; 18 - intrusive rocks (same legend for figures 4-13)
GradiSte Formation (rpa.D:HlliKa cBHTa) ( n e T p o s a e t a 1. , 1980) The name originates from Gradisko Kale peak, at 2.5km to the East of Varsilo Vil lage (TIe T p o B a et al., 1980). Other denominations are "flysch-like" horizon (K y n a Kc 'b 3 o B et al., 1962, 1964), "flysch-like series" (U: a H Ko s, 1968), "flysch
10 geological formation" (K 'h H q e B, 1971), "flysch-like formation" (TI on o B et al., 1980) and partly "Zelenkovska Formation" (TI e T p o B a, C u M e o H o B, 1988). The Formation is also described as graywacke-siltstone flysch (H a q e B, 1976a, s; H a q e B, C y J1 Ta H 0 B, 1979, 1991). The characteristic features of Gradiste Formation are connected to the mul tiple and rhythmic alternation (rhythms) of graywackes (or calcareous quartz sand stones), siltstones and shales, marls and limestones. The rhythms are complete (Th e) or base cut out (Tb-e, Te-e) and have a thickness up to 1.20m. Following the composition, this is graywacke-siltstone flysch (H a q e B, 1976a, b). The holostratotype is situated on Gradiste Kale Peak. The section to the North of Kosti Village and the section in the valley of Ve1eka River, near Brodilovo Village could be used for complementary sections and display (Fig. 3, 6, 7).
Cover: flysch of tephroturbidites and argillaceous limestones /Sinemorec Formation/. 3. Flysch with multiple, rhythmic alternation of graywackes for quartz sandstones/, siltstones and marls 30m 2. Thick-rhythmic flysch from graywackes for quartz sandstones/, siltstones and black hydromica shales 80m I. Thin-rhythmic alternation of calcareous, argillaceous siltstones and black hydromica shales jsubflysch/ !Om Basement: black siltstones, shales and argillaceous limestones /Cerovska Formation/. The Formation occurs as a stripe near the village of Aleksandrovo and especialy as a stripe from Varsilo Village through Veleka River to the state border. The thickness of the Gradiska Formation changes from 90 up to 130m. The rocks of the Formation lie with a transition (subflysch) over black shales, calcareous shales and argillaceous limestones of Cerovska Formation. Fossils in Gradiska Formation are extremely rare. Globotruncana linneiana (d'O r big n y),Hedbergella sp., Heterohelicidae andLenticulina sp. are determined. The age of the Formation is considered conditionally as Coniacian-Campanian. A part of the flysch provisionally is referred to the Turonian (I..J; a H Ko s, 1968; K'hH'IeB,l97l;KyJiaKC'h30B,1974).
Kubadin Formation (Ky6a.n;uHcKa CBHTa) (new Formation) The name comes from the village Kubadin, Southwest of the town of Sredec (previ ously Grudovo). The Formation was described as a packet of limestone and argilla ceous limestones into the limestone-tuff-tephroid geocomplex (H a q e s, 1976s, 1986; H a q e B, R He B 1980; H a q e B, C y JI Ta HoB, 1991). The rocks are included into the "Grudovo Series" (TIe T p o B a et al., 1980), but without sufficient grounds. The characteristic features ofKubadin Formation are connected to the alterna tion of grey, greenish to red limestones and argillaceous limestones. Locally and partly the limestones intercalate with layers up to packets of tephraturbidite rocks, bearing a resemblance to tephraturbidite flysch. The limestones are micritic with plankton foraminifers. In the southern outcrops they are poorly to completely silici fied, passing into cherts. The stratotype is along Sredecka River, between the villages Kubadin and Aleksandrovo (Fig. 6). Near the village of Veselinovo, northeastern of the town of Yambol, a convenient supplementary section is located. Cover: tephraturbidite flysch /Sinemorec Formation/. 3. Alternation between grey, greenish or red micritic limestones and argillaceous limestones fmarlsf. Some beds of tephra turbidites are observed. Locally and partly the limestones are silicified and altered into bedded calcareous cherts 60m
11 ~ VI Column Fossils Ql ~"' m C1t VI ...... 0 Column m Fossils Cn Vl vo vo .... o ...,o ... o 45 v. . Tn vo vo vo v. v. vo vo vo Cp v. v • __lo.O ... 0 vo Textul ariidae v...... Orbi t ol ina 'P . vo vo vo Cm Alg-. 55 Bryoza.~ ..... v • Bivalvia - part~ vo vo vo ..... v • 0 0 0 v. v. vo vo 0 v. v. Fig. 5. Upper Cretaceous in section Pitovo Vf> vo vo v. v. vo vo vo
V• ...... Heterohelicidae \,10 vo vo Hedbergella sp. v. V• Radiolaria vo vo vo v. v. 1000 St 0 0 ~· V• vo vo JO v. v. vo vo 0 v. v. vo vo 0 v. v. vo 0 0 v. v. vo vo vo
Cn ...... 420 ~ ...... -......
~ C> 0 .e:, ~ Fig. 6. Upper Cretaceous in section Aleksandrovo Um.. .,... .,.__,... 40
2. Micritic limestones in alternation with argillaceous limestones. The color is grey, greenish or reddish 70m I. Alternation of grey micritic limestones and dark argillaceous limestones 70m/ Basement: dark flysch of graywackes, siltstones and shales /GradiSte Formation/. The Formation occures in stripes and spots. It is well exposed as a stripe be tween the villages of Aleksandrovo and Varsilo (Fig. I). The second stripe is ob served between the town of Yambol and Draganci Village. Some isolated spots exist
12 between the Devetak Village and the town of Karnobat. A spot is observed between the villages of Novo Panicarevo and lzgrev. The thickness of the rocks of Kubadin Formation ranges from 50 up to 500m. The rocks of the Formation lie with a gradual transition over the Cerovska Formation. They follow also above the flysch of Gradiste Formation and probably replace and interfinger laterally with them. The fossils in Kubadin Formation are rare and untypical. The age of the Formation is considered conditionally as Coniacian and Santonian.
S i n em o r e c Form at i on (C H H eM o p c K a c a H T a) (n e w Form at i o n) The name is connected to the village Sinemorec, where numerous informative and spectacular sections occur. The rocks of the Formation are part of a "volcanogenic horizon" (K y JI a K c b 3 o B et al., 1962, 1964) and "sedimentary-volcanogenic for mation" (K y JI a K c b 3 o B, 1974). They are part of the "Grudovo and Burgas series (Groups)" (TIe T p o a a et al., 1980) or of the Kazaldiik, Novo Panicerovo, Tankovo, Medovo and Draganovo Formations" (TI o noB et al., 1980). The Sinemorec For mation includes parts of the rocks of the "Grudovo, Micurin and Burgas Group" (Geological Map, 1989) and of the "Burgas Complex" (TI JI o T H H K o a a, H a q e a, 1987). The characteristic features of the Sinemorec Formation are motivated on the mul tiple and rhythmic (rhythms) alternation of tephraturbidites (tephroid rocks) and limestones (Fig. 3, 4, 5, 6, 7, 8, 9). The tephraturbidites are bouldery, aglomeratic, lapillic, rudaceous, arenaceous, siltic and ashey. They have a litho-, crystallo- or vitroclstic texture. From genetical aspect they are tephraolistostromes, tephrafluxuturbidites, tephraturbidites, tephralaminites and tephracontourites. The limestones are micritic or argillaceous ("marls") and contain planktonic foramini fers. Some beds of chert zeolitic rocks occur, as well as bentonites. The rhythms are complete (Ta-e), base cut out (Tb-e, Te-e), with a thickness from 2 up to 20 em, random more. The rhythms are an element of the tephraturbidite flysch, of proximal or distal type. There is some internal flysch structures, hieroglyphs ang ichnofossils. The stratotype is situated on the cost from the town of Ahtopol to the village of Rezovo. The complementary sections are in the quarries for stones near the towns of Karnobat and Aytos. Cover: not exposed. 4. Tephra turbidite flysch consisting of lots of tephraturbidites and few beds of micritic limestones and argillaceous limestones. It is observed a frequent alternation with lava and pillow-lava flows . There is also some cutting dykes from porphyrites lOOOm 3. Tephraturbidite flysch consisting of lots of tephraturbidites and few micritic limestones. There are some beds of cherts, olistostromes, lava and pillow-lawa flows IOOOm 2. Thick-rhythmic flysch of tephraturbidites, micritic limestones and argillaceous limestones {marls/ 600m l . Thin-rhythmic tephraturbidite flysch of tephraturbidites, micritic limestones and argillaceous lime stones {marls/ 400m Basement: flysch of graywackes, siltstones and argillaceous limestones {Gradiste Formation/. The occurence of Sinemorec Formation is extremely broad. Its rock are wide spread over a big area between the towns ofYambol and Ahtopol and between Aytos and Nesebar. Small outcrops occur near the villages ofKosti, Sarkovo, Razdel, Kamen Vrah, Glousnik, Gorno Aleksandrovo and Venec (Fig. 1). The thickness of the rocks of the Sinemorec Formation is quite variable, reach ing at some localities up to 3000m.
13 Ql"' "'~ .....""d Column m Fossils 0 Column m Fossils Vl Vi V• V• Vo Heterohelix globuloN Glabotruncana tricarinat.t 0 v Globotruncan• linne.Una Contusotrunc.n• fornicat.t Globigerinelloides aspera 0 vo 1000 V o Vo Cp v v v 0
0 vo Cp 960
V o V o vo vo
St 1(11) v v v vo vo
v v v
vo vo v Cn • 700 St 680 rn 100 V Rotalipora cu.sJ.ani Pr•~lobotrunc&na sp. Cm 211) Nhiteinella sp.
Fig. 7. Upper Cretaceous in section Varsilo-Zidarovo
vo vo vo 350 Cn vo v vo
Heterohelic idae v Praaglobotruncana g.ibba Hedbergella sp . Fig. 8. Upper Cretaceous in section Straldia Rl Tn 112 Radiolaro.
The rocks of the Sinemorec Formation lie with a gradual transition over those of Cerovska, Gradiste or Kubadin Formation, replacing them or interfingering with them. The fossils in the Sinemorec Formation are relatively rare. Some typical microfossil associations (foraminefers) are found in the limestones of the Sinemorec Formation. The following microfossils have been determined up to now (Fig. 6, 7, 9): Heterohelicidae, Heterohelix globulosa (Ehrenberg), Globotruncana rugosa Marie, G. tricarinata (Q u ere a u), G. linneiana (d'O r big n y), Globotruncanita stuartiformis (D a I b i e z), Contusotruncanafornicata (P I u m m e r), Rugoglobigerina rugosa (P I u m m e r), Globigerinelloides aspera (E h r en berg), Hedbergella sp. and Radiolaria. The age of the Sinemorec Formation is Lower Senonian - Campanian. The sedimentary rocks of the Coniacian and the Santonian are indicated by foraminifer associations. The presence of the Upper Campanian is proven by the zonal species Globotruncana rugosa M a r i e.
Izgrev Formation (M3rpescKa csnTa) (new Formation) The name is given after the name of the lzgrev Village, northwest of the town of Carevo (previously Micurin). Its rocks are part of a "volcanogenic horizon"
14 (KynaKC'h30B et al., 1962, 1964; U.aHKOB, Kexauoaa, 1963; I..J.aHKOB, 1968), "sedimentary-volcanogenic formation" (K y JI a Kc 'h 3 o a, 1974), "volcano sedimentary geological formation" (K 'h H q e B, 1971). They are a part of "volca nogenic Senonian" (ll on o Bet al., 1980), the "Burgas Series (Group)" (ll e T p o a a et al., 1980) and "Complex of Burgas" (ll JI o T H H Ko B a, H a 'f e B, 1987). They have also been included in the limestone-tuff-tephroid geocomplex or "geological formation" (H a q e B, 1976a, a; 1986; H a q e B, ..H He a, 1980; H a q e a, C y JI T a H o a, 1991 ). as well as in the Burgas and Micurin Groups (ll e T p o B a, C H M e o H o a, 1989). The characteristic features of the Formation are related to the volcanic tuffs, with andesitic, basaltic, trahyandesitic, trachybasaltic and basaltoid composition. Their textures are bouldery to ashey. They associate with effusive rocks of similar composition. The stratotype of lzgrevets Formation is situated between Izgrev Village and the town of Carevo. The supplementary section is around Papia Volcano. Cover: not exposed. 2. Volcanic tuffs of basaltic, trachyandesitic, trachybasaltic and basaltoid composition. There is alter- nation between lavas and dykes 800m I. Volcanic tuffs of andesitic and andesitobasaltic composition 700m Basement: tephraturbidite flysch /Sinemorec Formation/. The volcanic tuffs of Izgrev Formation have little and limited occurence. They are observed in the Spaski, Tamarinski and Voiniski Bakadzik, Pravdino, Varli Bryag, Zidarovo, Rosen, around Papia volcano, etc. (Fig 1.) The thickness of the tuffs is variable and reaches up to 5000m. The volcanic tuffs interfinger laterally with effusive rocks from one side and with tephraturbidite flysch from other side. They lie mainly over the rocks ofSinemorec Formation or over effusive rocks. The tuffs do not contain fossils. The age of the lzgrev Formation is considered conditionally as Coniacian, Santonian and Campanian, based on its relations to Sinemorec Formation.
Glusnik Formation (rnyrnHHKCKa CBHTa) (new Formation) The Formation is named after the village Glusnik Village at 15km East of the town of Sliven. It has been described as part of the limestone-tuff-tephroid geocomplex (H a q e B, 1976a; 1986; H a q e B, ..H He B, 1980; H a q e B, C y JI T a H 0 B, 1991). The characteristic features of the Glusnik Formation are related to the pres ence of grey up to reddish micritic and argillaceous limestones. The limestones are partly ironized. They contain also chert concretions, bedded cherts Gasper) and manganese ores. The stratotype is near the Glusnik Village (Fig. 10, II). Cover: flysch consisting of clastic limestones, micritic limestones and argillaceous limestones fKonjovo Formation/. 2. Red and grey micritic limestones in alternation with argillaceous limestones. There are chert concre- tions and manganese ores 15m I. Red micritic limestone in alternation with grey argillaceous limestones /marls/ 25m Basement: tephratubiditic flysch /Sinemorec Formation/. The occurence of the Glusnik Formation is restricted only in the northenmost outcrops: Bjala, Sliven, Glusnik, Gorno Aleksandrovo and between the town of Aytos and Bata Village (Fig. 1, 10, 11 ).
15 .. "' Ql .. 01 Column m Foss i ls c Column m Fossils ""0 Vi Vi
Haplaphragmoides coron.tt.t cibicides vol t:zianus Gyro1d1na globosa contusotruncaM contusa Globotrunca.ni U stuart.i Globotru.ncana tricarinat.t Siderolites calcitrapoides Cp Orbi toidea INdia 150 Rugoglobigerina rugosa Algae, Bryozoa P•eudotextularia eleg.ns
280 11t v • ..,.
St vo . ' Fig. I 0. Upper Cretaceous in section Gorno Aleksandrovo
Globotrunc~a rugosa Globotruncanit.1 stuartilolliJis V• ~ V • Cootusotruncana fornicata Cp 140
Fig. 9. Upper Cretaceous in section Dryankovec The thickness of the rocks is from I 0 up to 200m. The rocks of the Glusnik Formation lie over Sinemorec Formation with a sharp contact, locally with a submarine erosion. In the rocks of Glusnik Formation mainly planktonic foraminifers and micro fossil associations are found. The following taxa have been determined: Globotruncana tricarinata (Q u ere au), Globotruncana bulloides Vogler, Contusotruncana fornicata (PI u m m e r), Rugoglobigerina rugosa (PI u m m e r) and Pseudotextularia elegans (R z e h a~) . The age of the Glusnik Formation is Campanian.
Konjovo Formation (KOHhOBCKa CBHTa) (new Formation) The name is given after the village Konjovo, 15km to the east of the town of Nova Zagora. The Formation is a part of the limestone horizon (I.( a H K o· B et al., 1962), "Burgas complex" (ll JI o T H H Ko B a, H a 'I e B, 1987), "flysch formation" (Geologi cal Map ..... , 1989). The characteristic features of the Konjovo Formation are related to multiple and rhythmic (rhythms) alternation of clastic limestones, micritic limestones and argillaceous limestones. The clastic limestones contain quartz and go transitionally to calcareceous sandstones. They have rudaceous, arenaceous and silty texture. They are often silicified and go transitionally into diagenetic bedded cherts. Some beds of bentonites occur. The rhythms are complete (Ta-e) and base cut out (Th-e, Te-e) and
16 have a thickness up to 1.20 m. The rocks of the Formation have been determined as clastic-limestone flysch (H a'~ e B, 1976a, a; 1986; H a'~ e B, ..sl He a, 1980; H a'~ e B, CyJITaHos,I991). The holostratotype of the Formation is near the Konjovo Village, at the quar ries for extraction of "Konjovo stone" for the house-construction and the sections are demonstrative. Cover: not exposed. 2. Flysch consisting of white clastic limestones, micritic limestones and grey argillaceous limestones jmarls/. A part of the clastic limestones are silicified and transformed into bedded chert rocks. There are chert concretions and single beds of bentonites 300m I. Grey-white flysch of clastic limestones, micritic limestones and argillaceous, limestones 200m Basement: tephraturbidite flysch jSinemorec Formation/ or micritic limestones and argillaceous lime stones /Giusnik Formation/. The occurence of the Konjovo Formation is restricted between the towns of Nova Zagora and Yambol. To the north, in the sections Glusnik, Garno Aleksandrovo and others, the rocks are replaced by a packet of limestones and argillaceous lime stones. Probably to the east of the town of Yambol, Konjovo Formation had not been deposited. The thickness of the Konjovo Formation changes from 200m up to 1OOOm. The Konjovo Formation lies with a transition over the Sinemorec Formation. The sections end with it, therefore there are no data on the cover. In the rocks of the Konjovo Formation, detritus of undeterminable benthonic fossils is found in the clastic limestones, and planktonic microfossils (foraminifers) in the micritic and argillaceous limestones. The age of the Formation conditionally is Campanian.
Dryankovec Formation (,[(pRHKOBeiua CBHTa) (new Formation) The Formation is named after the village Dryankovec, I Okm to the East of the town of Aytos (ll n o T H H Ko B a, H a q e B, 1987). Other used names are "calcareous ho rizon" (U: a H Ko B et al., 1962; U: a H Ko B, 1968), "flysch geological formation" (K 'b H q e B, 1971) and "Emine Flysch Formation" (Geological Map ..... , 1989). The characteristic features of the Dryankovec Formation are related to the presence of sandy limestones and calcareous quartz sandstones and siltstones. There are also few breccias, conglomerats, argillaceous limestones and calcaraceous clays. The lower part of the Formation is rhythmic with alternation of sandstones and limestones, the upper part consists of limestones-sandstones. In the section Ljulin there are especially sandy and biomorphic limestones with benthonic fauna. The stratotype of the Formation is the section Dryankovec. The supplementary section is that near the Ljulin Village (Fig. 9, 12, 13). Cover: not exposed. 4. Packet of calcareous sandstones and sandy limestones 60m 3. Packet of micritic limestones, argillaceous limestones and calcareous sandstones 70m 2. Rhythmic packet of calcareous sandstones and calcaraceous clays or of sandstones, siltstones, lime- stones and argillaceous limestones /marls/ 160m I. White micritic limestones in alternation with grey argillaceous limestones /marls/ 20m Basement: tephraturbidite flysch with olistostromes /Sinemorec Formation/. The occurence of the Formation is limited only in two outcrops near the vil lages of Dryankovec and Ljulin (Fig. 9, 12). The thickness of the Dryan'kovec Formation is up to 600m.
2 Geologica Balcanica, 25, 3-4 17 "'Ql Column 1 , , Fossils "'d t;
Contusotnmcan.a fornic.J.ta Clabotruncana bulloide• Rugoglobigerina rugosa Ill Ql "' Column m Fossils Vl.e
vo vo 0 Cp v V • 520 v C1bicid• • vol tzianua Praebul i11ina caraey.ae St trn sioina exsculpta V • V • Globotruncana .rea v vo vo Sider ol i t•• calci trapoidea Mt 20 Orbi toi de• 111edi a rextul ari idae ~ V • vo v· V • v V• V • ..... v V · v· v •
vo vo St v 200
v· v • Cp • • • v vo • I
Fig. II . Upper Cretaceous in section Miroljubovo Fig. 12. Upper Cretaceous in section Ljulin
The rocks of the Formation overlie the Sinemorec Formation with an unconformity in section Ljulin. The relations in section Dryankovec are not clear due to the limited exposure, but probably it lies over the Glusnik Formation. Benthonic macrofossils - Inoceramus, and other bivalves, brachiopods, and others (L j u I i n) occur in Dryankovec Formation. The following foraminiferal taxa are determined: Rhabdammina sp., Trochammina sp., Haplaphragmoides coronata B r ad y, Cibicides voltzianus (Reuss), Praebulimina carseyae (P I u m m e r), Stensioina exsculpta (Reus s),Gyroidina globosa (Hagen o w),Globotruncana area (Cushman), Globotruncanita stuarti (Lapp are n t), Contusotruncana contusa (Marie), C. fornicata (PI u m m mer), Siderolites calcitrapoides Lam arc k, Orbitoides media Arch i a k, 0. sp., Textularidae, Algae, Bryozoa. The age of the Dryankovec Formation is proven as Maasrichtian.
Chronostratigraphy The Upper Cretaceous chronostratigraphic volume in the Eastern Sredna Gora Zone includes the stages Cenomanian, Turonian, Coniacian, Santonian, Campanian and Maastrichtian (Fig. 2).
Cenomanian The Cenomanian rocks crop out as stripes near the villages of Gavrailovo, Banja, Padarevo, Pitovo, Boyadzik, Kamenec, Aleksandrovo, Kamen Vn1h, Varsilo, Krusevec, Vizica and Kosti (Fig. 1). To the Cenomanian have been referred conditionally the continental limnic coal-bearing sediments (KardifFormation). Of proven Cenomanian age are the shal low-water rocks - conglomerates, microconglomerates, sandstones, siltstones, shales,
18 sandy limestones, biomorphic limestones and dolomites (lower part of Cerovska Formation) (Fig. 2-8). The Cenomanian rocks lie with a parallel to angular unconformity over Juras sic, Triassic and Paleozoic sedimentary rocks and granites. The thickness changes up to 120m for the limnic rocks and up to 220m for the shallow-marine rocks (tabl. 1). Fossils have not been found in the limnic rock. The shallow-marine ones have been prouven mainly by Orb ito/ina (K y JI a K c 'b 3 o B et al., 1962, 1964; K 'b H 'I e B, 1971; H H K 0 JI 0 B, 1979; TI e T p 0 B a et al., 1980). The macrofossils are shallow-water hippurits. The foraminifers are benthonic and planktonic. The following taxa have been determined: Orbitolina concava La m arc k, Nezzazata simplex 0 m a r a, Pseudolituonella sp., M i 1 i o 1 i d a e, Text u 1 a r i d a ~ Rotaliopora cushmni M o r r o Vt4 Praeglobotruncana sp., Whiteinella sp., Hedbergella sp., and Heterohelicidae. The planktonic foraminifers are characteristic for the Upper Cenomanian.
Turonian The rocks of the Turonian crop out as stripes. The outcrops coincide with these of the Cenomanian (Fig. 1). The Turonian is represented by shallow-marine clastic, calcaraceous and argilla ceous rocks (upper part of the Cerovska Formation). The clastic rocks are conglom erates, microcong1omerates, quartz sandstones and siltstones. The argillaceous rocks are dark to black illite shales. The limestones are sandy, argillaceous, grainy, micritic and biomorphic (hippuritic)) (Fig. 4-8). The Turonian rocks lie with a transition over those of the Cenomanian. The thicknesses of the Turonian rocks are from 15 up to 300m. The fossils in the Turonian are rare and uncharacteristic. The foraminifers are mainly planktonic. The next taxa have been determined: Praeglobotruncana gibba (K 1 au s s), Hedbergella sp., Heterohelicidae and Lenticu/ina sp.
Coniacian The rocks of the Coniacian are relatively widespread. They have been established mainly in the southern and southwestern outcrops (Fig. 1). The rocks of the Coniacian are represented by deep-water diverse in type rocks. A rhythmic alternation of graywackes, siltstones and shales or of argillaceous lime stones (Gradiste Formation) has been established. In other sections there are mainly micritic limestones in alternation with argillaceous limestones (Kubadin Formation). The tephraturbidite flysch (Sinemorec Formation) consists of rhythmic alternation of tephroid rocks with micritic limestones and argillaceous limestones. Probably the volcanic tuffs in the lower parts of single sections are also of Coniacian Age (lzgrev Formation) (Fig. 2-8). The rocks of the Coniacian lie with gradual to fast transitions over the Turonian ones. The thicknesses of the Coniacian rocks change from 60 to 720 m. The fossils in the Coniacian are extremely rare and uncharacteristic. The fora minifers are planktonic. Only Heterohelicidae, Hedbergella sp. and G/obotruncana /inneiana (d '0 r big n y) have been found.
19 N 0 Tab I e I Thickness (m) of the Upper Cretaceous stages
Section Cenomanian? Cenomanian Turonian Coniacian Santonian Campanian Maastrichtian
Pitovo 70 30 270+ Grafitovo 25 25 350 550 100+ Omarcevo R-1 250+ 270+ Konjovo 900 Korten 30 40 60 180 1380 Sadiisko Pole 60 70 450 520 2000 Strupec-Kamenovo 80 30 490 400 700 Kovacite 260+ Belenska River 60 720 820 810 Gavrailovo 30 90 120 300 600 910 Sliven 350+ 650 Sarkovo 15 15 290 450 Kamen Vrah 90 120 180 620 Aleksandrovo-Ljulin 40 40 420 1000 1500 20+ Kubadin 510 510 Glusnik 30+ 240+ Garno Aleksandrovo 77+ 225+ Straldza R-1 112 350 680 968 Venec 300+ 900 Karnobat 200+ Fakiiska River 30 30 440 700 Aytos 220+ Dryankovec 140+ 270 Sadievo 400+ 440 60+ Miroljubovo 300+ 420 Brestnak-Emirsko 700 300 Tankovo 100+ 670 30+ Pomorie R-1 1000+ 1800 Varsilo-Zidarovo 200 100 700 1000 1000 Krusevec 220 80 500 900 320+ Cerovska River 120 80 100 380 180+ Vizica 60 60 150 390 540 1000 Kosti-Balgari 90 300 610+ Brodilovo !50 120 400 850 1080 Rezovo 530 1470 Santonian The rocks of the Santonian crop out as stripes and often over broad areas. They are relatively widespread (Fig. 1). The Santonian is represented by diverse in types deep-water sedimentary rocks. In some individual southern sections there is a rhythmic alternation of graywackes, siltstones and argillaceous limestones (upper part of the Gradiste Formation). In part of the sections, the Santonian consists of micritic limestones in alternation with ~rgillaceous limestones (Kubadin Formation). In most of the sections, the Santonian is represented by multiple and rhythmic alternation oftephroturbidites rocks, micritic and argillaceous limestones or of tephraturbidite flysch (Sinemorec Formation). The volcanic tuffs in the lower part of the sections are probably also of Santonian age (lzgrev Formation)) (Fig. 2, 3, 4, 6, 7, 8, 10, 11). The rocks of the Santonian lie with a gradual transitions over the Coniacian ones. The thicknesses of the Santonian rocks are from 180 to 1000 m. The fossils in the Santonian are also represented by rare and uncharacteristic specimens of Heterohelicidae and Hedbergella sp.
Campanian The rocks of the Campanian crop out as stripes or as relatively broad areas. They occur mainly in the central and northern parts of the Eastern Sredna Gora Zone (Fig. 1). The Campanian is represented by various deep-water rocks. In the southern sections, there are alternation of micritic limestones and argillaceous limestones (Kubadin Formation). In many of the sections and in a broad area the Campanian consists of rhythmic alternation of tephroturbidites, micritic limestones and argilla ceous limestones or tephraturbidite flysch (Sinemorec Formation). In the section of Korten, Konjovo and Kermen, a rhythmic alternation of clastic limestones, micritic limestones and argillaceous limestones to calcareous clays occurs, with concretional and bedded cherts or clastic-limestones flysch (Konjovo Formation). In the north ernmost sections between the town of Sliven and the village of Bata (Fig. 1) there is a packet of micritic limestones in alternation with argillaceous lime "'.. Column m Fossils stones (Glusnik Formation). A big part 2 of the volcanic tuffs (lzgrev Forma Vl Heterohelix sp. tion) are probably also of Campanian · ' · · · · 300 Globotruncana l1nnei4JUI Mt Textulariidae Age (Fig. 2, 4, 6-13). Siderolitea lfp. The rocks of the Campanian lie with gradual transitions over the Santonian ones. The thickne.sses of the Cam panian rocks change from I 00 to 700 Heterohelicidae ...... • Hedbergella sp. 2000 m. Cp The fossils in the Campanian are relatively more frequent and locally ""'" ....,, characteristic. Single representatives of v v inoceramus have been observed. The foraminifers are mainly planktonic. The microfossil associations in the Fig. 13. Upper Cretaceous in section Brestak-Emirsko
21 Ku lakaazov et Tzanlcov, Keha Tsankov et a l., Ianchn, 1971 kulaksazoT, Hikolov ,1 979 al., 1962 ,1964 yova, 196} 1962 • TzankoT, 1974 196}
limestones h. flyocb flysch flysch horiz. Toloanogene - fljachliko tic horizon form•tion !oraation Mt horicon Mt ll&rly-liM - voloanogene - stonea horizo Mt tic horizon tuff-volcano- liii,Y flyoob lgealc horison !ora, lUte 11n1 tial bre- !ora. coia horizon volo-.noge - •l'lj neti o - oodi•oatary- s Toloa.aopne- v olcanogene- sedi t~~en tar;r formf.tion tic tor.ation tic horiZOA cp flyoo~~like t. tuf a conglo•erate- s;, sands-arlr !ormatioll sn
l i mes t ones - •arlY sn, !ormation ("couches roup•")
nrochliko horison
flyschliko flys ch shales ,coal seauence !lyooh form•tion overooal ail ts'tonea • !ormation sandstones overc oal horizon Tn sandstones, boriZOA Tn coaly horizon Tn Tn conglomerate• n shales horiz . marlt T sequence initial horb, - limeetones t overoo&l eand•tonea aarly sandy-caloare- foraatioa oua horizon 11&1'11 seq. tuffs, tuffe- ccalboaring sandston.;a coal quartzized - roraatioa. crr Cm cm c oal bearing cm limestones, Cm boris on sandstone h formJ.tion ail tstone h marla aandatoll. l.aitial sandatooe h. conglomerates sandstones, ooqlo•rate conglomerate h . a and• tone a conglomerate s tor.ation
Fig. 14. Overview of the Upper Cretaceous stratigraphy in the Eastern Sredna Gora zone. Campanian include the following species: Heterohelix globulosa (Ehrenberg), Globotruncana tricarinata (Que rea u),G. linneiana (d' 0 r big n y),G. rugosa Marie, Globotruncanita stuartiformis (D a I b i e z), Contusotruncanafornicata (P 1 u m mer), Rugog/obigerina rugosa (P 1 u m mer), Pseudotextularia elegans (R z e h a k) and Globigerinelloides aspera (Ehrenberg). The speciesGlobotruncana rugosa Marie is zonal and proves the presence of Upper Campanian. Maastrichtian The Maastrichtian has a limited occurence in the Eastern Sredna Gora Zone. It has been determined only in the outcrops near the villages of Ljulin and Dryankovec (Fig. 1). The Maastrichtian is represented by shallow-water sedimentary rocks. In the section ofLjulin (Nedjalsko) there are breccias, breccia-conglomerates, sandy lime- 22 Petrova et al., Popov et al ., Plotnikova, Pe trova, S ime Nac hev, Diait 1980 1980 llac heY, 1987 onov, 1 9f\9 rova, 1992
imine Drjanlcovec Drjankovec Mt flysch Mt Formation Mt F erma t1 on
aedi.. nta:rr Foraation
cover Draganovo Por.
Medovo For•. c Cp p 'l'inltovo Fora.
Demirkeui J § ~··0 tt_ormation 0 llourgae Draganovo P. ~o·...,o~ 61'l'ikl1tska :;! <>,.... ~ .. ~formation ~ gJlodO"
• Tn , marly 0 Tn Tn Cercrt'o ~ !ormation "' Formation 0 .... - .... Cerovo .. Zelookovo Formation c:" •f4 'Poraation Cm ... {.oandatonol ~ardit forll&tion)
stones and biomorphic limestones. In the section of Dryankovec, the lower part consists of alternation of calcareous sandstones and siltstones with micritic or argilla ceous limestones. In the upper part some calcareous sandstones, argillaceous lime stones and sandy limestones (Dryankovec Formation) occur (Fig. 2, 9, 12, 13). The rocks of the Maastrichtian lie with an angular unconformity over a washed out surface of the tephra turbidite flysch (Sinemorec Formation) or over a packet of micritic limestones and argillaceous limestones (Glusnik Formation). The thickness of the Maastrichtian rocks is from 20 to 270m. The fossils in the Maastrichtian are comparatively frequent or occur in a large numbers (L j u I in). In the section of Ljulin there are lots of benthonic fossils repre sented by algae, echinoderms, bivalves, brachiopods, orbitoids, etc. (ll, a H K o B et al., 1962; li, a H K o B 1968). The following taxa have been reported: Lithophyllum sp.; Siderolites calcitrapoides Lam arc k. Simplorbites gensacicus (Ley mer i e),
23 Orbitoides media (d'Arc hi a c), 0 . apiculata S chI umber g e r, 0. tissotu S c h I u m be r g e 1; Crania antiqua De f r a n c e, Rhynchonella rionensis A n t h u I a, Pecten cicatrisatus G o I d f u s s, Pycnodonta vesicularis L a m a r c k, Exogyra decussata Co qua r d,Pyronea sp., Coraster vilanovae Cot tea u,Physaster sp., Hemipneustes striato-radiatus d' 0 r big n y (U: au K o B et al., 1962, 1981; IJ: a H K 0 B, 1968; 1982). The microfossil associations in the Maastrichtian are extremely rich. The fol lowing taxa have been determined: Rhabdammina sp., Haplaphragmoides coronata Brady, Cibicides voltzianus (Reuss), Stensioine exsculpta (Reuss), Gyroidina globosa Hag e n ow, Contusotruncana contusa (C us h m a n~ G. jornicata (P I u m m e r), G/obotruncanita stuarti (L a p p a r e n t), G/obotruncana tricarinata (Q u e rea u), G. area (C us h m an), Siderolites calcitrapoides Lam arc k, Orbitoides media (d'Arc hi a c), Orbitoides sp., Textularidae, Algae and Bryozoa. The mentionned association defines a Maastrichtian (and especially Upper Maastrichtian) Age of the rocks in the sections of Ljulin and Dryankovec.
On the geological evolution Probably at the end of the Early and the beginning of the Late Cretaceous (Cenomanian) alluvial, lake and swamp sediments had been deposited, in a limnic facies environment (KardifFormation). The marine transgression had followed dur ing the Cenomanian Age. In quite shallow-water environments Cenomanian and Turonian clastic, calcareous and argillaceous sediments (Cerovska Formation) had been deposited. In the end of the Turonian and the beginning of the Coniacian times (Early Subhercynian movements), the geodynamics had changed significantly. The Sredna Gora intra-arc Trough (Coniacian-Campanian) had originated through ex tension in the limits of an island-arc system. It has been localized between the Macedono-Rhodope and the Balkanide arcs. The processes of normal sedimenta tion with deposition of hemipelagic micritic limestones. Argillaceous limestones and calcareous shales had been combined rhythmically with processes of diverse in type resedimentation. In this way, have been formed different rocks and associations (Coniacian-Campanian): flysch of graywackes, quartz calcareous sandstones, silt stones and shales or argillaceous limestones (Coniacian-Santonian, Gradiste For mation); micritic limestones in alternation with argillaceous limestones and few tephraturbidites (Coniacian-Campanian, Kubadin Formation); tephraturbidite flysch (Coniacian-Campanian) oftephroid rocks, micritic limestones and argillaceous lime stones (Sinemorec Formation); volcanic tuffs (Coniacian-Campanian, Izgrev For mation); limestones and argillaceous limestones (Campanian, Glusnik Formation); clastic-limestone flysch (Campanian) of clastic limestones, micritic limestones and argillaceous limestones (Konjovo Formation). The Coniacian-Campanian rocks as sociate with effusive rocks - necks, lava flows and dykes - caused by subaquatic volcanism. They associate also with intrusive rocks - plutons, sills and dykes - related to intrusive magmatism. After the Campanian in result of compression, fold ing and uplift (Late Subhercynian orogeny) the Sredna Gora Trough has been closed. During the Maastrichtian, shallow-water limestones or micritic, argillaceous and sandy limestones in alternation with quartz sandstones (Dryankovec Formation) had been deposited. The paleogeodynamic environment represented superimposed relic shallow sea (Fig. 2).
24 References A i e II o, E., Ba r to I i n i, C., B o c c a I e t t i, M .• Co c e v, P., K a r a gj i I eva, J., K o s t a d i n o v, V.. M a n e t t i, P. 1977. Sedimentary Features of the Srednogorie zone (Bulgaria): an Upper Cretaceous intra-arc Basin. - Sedirn. Geol., 19; 39- 68. Go c e v, P.M. 1970. The Senonian Complex in Srednogorie zone. -C.P. Acad. Bulg. Sci., 23, 8; 975- 978. E 0 H 'I e B, r. 1917. CeOUMeHmHume CKa/IU 6DMZapUJI. - C6. 6AH, 7, 3; 162 c. Eo H 'I e B, EK. 197l.llpo611 eMu Ha 6uzapcKama zeomeKmoHuKa . C., TeXHHKa; 204 p. E 0 weB, c .. B au e B, M. 1977. ropHOKpC.!I.HTHHliT ljlnaw B IOJKHa 6MrapHll. - Cn. DMZ. ZC0/1 . 0 -60, 38. 2; 127- 139. Eo ll .a. lK H e B, C. 1979. Cpe.a.HoannHiicKHliT MarMaTH3"bM OT Cpe.a.HoropcKaTa 30Ha B ycJIOBHliTa Ha TenecKonHpaHa pHijiToreHe3a. - Cn. DMZ. zeo11. 0-60., 40, 3; 224- 235. BaCH Jl e B, Jl., Jl H Jl 0 B, n . 1971. ~aHHhle o6 a6COJIJOTHOM B03paCTC HeKOTOphiX .,JiaMHpHHCKHX" HHTPY3HBOB BoCTO'!Horo Cpe.a.Horopbll - l(oKII. DAH, 24, 3; 341 - 343. ~a 6 o B c K H, X. l988. llyKmUHHU uHmpyJuu 6 CpeOHozopuemo. C .• EAH; 184 c. 3 Jl aT a p c K H, r . 1910. ropHOKpe.a.HaTa HJIH HCOKpCTaLtCHCKa cepHll B EMrapHll. -roo. CY .•
25 U. a H K o 8, B., K e x a j.j o 8 a, M. 1963. lieneJICKH 81>pxy CTJ>aTHrpaqmliTa Ha ropHaTa Kpella H naneoreHa 8 AiiTOCKa CTapa nJiaHHHa. -roo. CY., EuoA. -~eOA. -~eo~p. ljjaK., KH . 2 leOA ., 56; 51-59. U. a H K o 8, B., K y n a K c , J o 8, r ., C a 8 o 8, C. 1962. lieneJICKH 81>pxy CTJ>aTHrpaHliTa Ha ceHoHa 8 IOfOHJTOqHHTe qacTH Ha ~M60JICKa o6nacT. - roo. CY. . EuoA. -~eOA . -~eo~p. -ljjaK. . KH. 2. ~eOA., 55; 29 - 43. ~ H Hille 8 c K H, A. 1946. KpaTKO HJJIOJICeHHe 8bpxy reonorHliTa Ha CTpaHllJICa nJiaHHHa. - roo. J1up. ~eOA . MUHHU npoy'l6., A, 4; 380- 388.
26