GEOLOGICA BALCANICA 23. 6, Sofia, Decemb. !993, p. 3-24.
Middle Tithonian to Berriasian praecalpionellid and calpionellid zonation of the Western Balkanides, Bulgaria
Iskra Lako va
Geological Institute, Acad. G. Bonchev Str., 24, 1113 Sofia lReceived 25. 05. 93; accepted 07. 06. 93)
H. JlaKoaa - 3oHupoaaHue 6 uumepaa,1e om cpei>ue
Introduction In the area of the West Balkan Mountains in West Bulgaria the Upper Jurassic and Lower Cretaceous carbonate deposits are of wide occurrence. Several formations composed of diverse limestones of Callovian to Barremian age have been jointed into the so-called Westbal kan Carbonate Group (Sap uno v, 1976, p. 18). The Glozhene Formation of the West balkan Carbonate Group is of particular interest for the calpionellid biostratigraphic study. This formation is characterized by grey micritic pelagic limestones and is of early Titho ~ian to Berriasian age (H H K o n o B, Can y HoB, 1970, p. 1398). The Glozhene micritic hme~tones have yielded rich and diverse calpionellid associations. Representatives of the prae calp10nellid genus Chitinoidel/a Do ben have been found in both the Glozhene and Ginci For m~tions, the latter underlying the former. The Ginci Formation has been introduced by Ntkolov and Sapunov (H H K o n o B, C a 11 y H o B, 1970, p. 1398) and is represented by grey to pink clayey nodular limestones of late Callovian to middle Tithonian age. The Ginci
3 0 5 10km
SVOOE
1@1, 02 tlSOFIA 1-%
Fig. I. Main outcrops of the Westbalkan Carbonate Group (incl. the Glozhene and Gintzi Formations) in the study area and location of the sections studied 1 - outcrops of the West Balkan Carbonate Group (af ter Gelogical Map of Bulgaria, 1989); 2- Komshtit za section; 3 - Barlja section
Formation is similar in its lithological features and the presence of praecalpionellids in its upper part to the "Rosso Ammonitico" sequence of the Venetian Alps as desribed by G ran d e s s o (1977). The calpionellid biostratigraphic investigation of the Tithonian-Berriasian carbonate sequence in Bulgaria has been pioneered by D. Bakalova (E aKa noB a, 1977). In the widely known Jurassic-Cretaceous boundary interval section at the village of Ginci (Wes tern Balkanides) all standard calpionellid zones from Crassicol/aria to Calpionellites have been established (B a k a 1 o v a, 1977). Later, the same author has divided the Calpionel/a Zone into three subzones: C. alpina, Remanie/la and C. e!liptica (B a k a I ova - Ivan o va, 1986).
Calpionellid zonation m the Mediterranean regwn
Remane (1963, 1964, 1971) and Remane in Le Hegarat, Remane (1968) has proposed the first calpionellid zonation of the Upper Tithonian, Berriasian and Valan ginian in SE France. After the Second Planktonic Conference in Rome, 1970, a standard calpionellid zonation has been established of the Western Mediterranean province (A 11 e m ann et al., 1971) which has soon been widely accepted and proved by a number of authors. The Rome standard zones serve now as a basis for the calpionellid zonation and correlation of the whole Mediterranean region. Reman e (1985, 1986) has presented a summari zed correlation of calpionellid zonations (Fig. 2). The present author has completed it with some recent zonal schemes in different countries mainly of the Southern Mediterranean pro vince, e. g. Western Carpathians in Slovakia (B o r z a, 1984; B o r z a, M i c h a 1 i k, 1986), Southern Carpathians in Romania (P o p, 1986; P o p, M e 1 i n t e, 1992), North Western Anatolia in Turkey (A It in e r, 0 z k an, 1991) and Western Balkanides in Bulgaria (B a k a I o v a, 1977; B a k a 1 o v a - I v a n o v a, 1986). Data on the calpionellid occurrence in the two sections studied in WesternBalkanides made it possible to establish praecalpionellid and calpionellid zones from the Chitinoidella
4 T/111/M"'J- .1#/11 (Tint inn~- .1#//11
CI/JI/0 Cl lp lt~- fCI Ipio- Clllp io- 11 ~ 11114$ 11 ~ 1/iUs n1111ruJ 11~ 1/lt~s
A3 , . ~ Cr. ,;,v- Cr1s.11- Cr1u1- i~ t/hil/11 Cressio lf1rl1 ctllllr/11 ~i ~;~; H~ COilN/I ca- ~~- ~ Al t~ a r. "_,., r~m111' 1 "1"11 I - ~~i,, 111f1MH!/I ~~ llon'rl Chi tlntJ- CllltlntJ- ~ ~ C!J. b.1Nti l d,/11 /dillI ~~- ~ ~~~ ~ ... en. do!J4nl i
Fig. 2. Correlation of calpionellid zonations from recent publications (after Reman e, 1986, completed by the present author)
Zone in the Middle Tithonian to the Calpione/lopsis Zone in the upper part of Berriasian and to prove eight subzones.
Description of the sections
Two sections of the Tithonian-Berriasian carbonate succession in the Western Balkanides have been studied. Komshtica section is situated at the northern end of the village of Kom shtica on the right bank of Visochica river. Barlja section is located some 2-3 km north of the village of Barlja. Both sections, together with the earlier investigated Ginci section (B a k a- 1 o v a, 1977), belong to the stripe-like exposure of the We stbalkan Carbonate Group north of the town of Godech (Fig. I). In Komshtica section 48 m of grey micritic limestones (Glozhene Formation) are ex posed whereas in Barlja section the thickness of this formation is 38m. In both sections the Glozhene limestones are underlain by the Ginci Formation and overlain by the Salash Formation (N i k o 1 o v, 1969, p. 60) which represents aphanitic and clayey limestones with intercalations of marls. In Godech area the Salash Formation is of Berriasian to Bar remian age (H K K o JI o B, U a H K o a, 1971). The whole thickness of the Glozhene For mation and the top of the Ginci Formation have been sampled at each I m and thin sections have been prepared. Quantitative study of the calpionellid associations has been carried out. Counts have been made on an area of 1 cm2 of each thin section using 25 x and 12,5 x objectives and lO x eye pieces of Jenaval transmitted light microscope. The number of spe cimens of praecalpionellid and calpionellid species and the total number of specimens have been determined for each thin section. These data on Komshtica and Barlja sections are shown on Figs. 3 and 4 respectively . This study has provided also data on the relative abundance of each species in percentage of calpionellid faunas. The last results are shown on Fig. 5 (Komshtica section) and Fig. 6 (Barlja section) and they have allowed to make biostratigraphic conclusions and to illustrate the taxonomic content of the zones and sub zones. Similar study has been undertaken earlier by Remane (L e H e g a r a t, R e m a n e, 1968).
5 Komshtica section
Sa1ash Formarion (upper part of Berriasian-Barremian) Aphanitic and clayey limestones intercalated by marls sharp lithological boundary Glozhene Formation (samples No No 247-0201) (48 m) (Middle Tithonian, p.p. -upper part of Berriasian, p.p.) Grey micritic pelagic limestones Calpionel/opsis Standard Zone (p. p.) (244-247) (4 m) (upper part of Berriasian, p. p.) Calpionel/opsis simplex Subzone (p. p.)(244-247)(4 m)(upper part of Berriasian, p. p.) Calpionellid association: Tintinnopsel/a carpathica, Ca/pione/la a/pina, Remanie/la cadischiana, Calopionella elliptica, Tintinnopsella tonga, Calpionellopsis simplex. Ca/pionel/a Standard Zone (219-243) (25m) (Upper Tithonian -lower part of Berriasian) Ca/pionel/a el/iptica Subzone (238-243) (6 m) (lower part of Berriasian) Calpionellid association: T. carpathica, C. alpina, C. elliptica. R. cadischiana, T. tonga Remaniel/a Subzone (235-237) (3 m) (lower part of Berriasian) Galpionellid association: C. a/pina, T. carpathica, R. cadischiana, Crassico/laria parvula Calpionel/a alpina Subzone (219-234) (16 m) (Upper Tithonian -lower part of Berria sian) Calpionellid association : C. a/pina, T. carpathica, Cr. parvula, Crassico/laria co/omi Crassico/laria Standard Zone (207-218) (12 m) (Upper Tithonian) Crassicol/aria massutiniana Subzone (213-218) (6 m) (Upper Tithonian) Calpionellid association: T. carpathica, C. a/pina, Crassico/laria massutiniana, Crassicol/aria brevis, Cr. parvula, Crassicollaria intermedia, homeomorph Calpionel/a elliptica. Tintinnopsel/a remanei Subzone (207-212) (6 m) (Upper Tithonian) Calpionellid association: T. carpathica, Cr. intermedia, Cr. massutiniana, Tintinnopse/la remanei, Prae tinnopsel/a andrusovi. Praetintinnopsella Zone (205-206) (2m) (Middle-Upper Tithonian boundary interval) Association: Praetillfinnopsella andrusovi, T. carpathica, T. remanei, Chitinoidella boneti. Chitinoidel/a Zone (p. p.) (0201-204) (6 m) (Miiddle Tithonian) Chitinoidel/a boneti Subzone (200-204) (5 m) (Middle Tithonian) Association: Chitinoidella boneti, Chitinoidella sp., Pr. andrusovi. Chitinoidel!a dobeni Subzone (p. p.) (0201) (1 m) (Middle Tithonian) Chitinoidella sp. rapid lithological transition Ginci Formation (p. p.) (Middle Tithonian) Grey to pink clayey nodular limestones Chitinoidel/a Zone (p. p.) (0206-0202) (5 m) (Middle Tithonian) Chitinoidel/a dobeni Subzone (p.p.) (0206-0202) (5 m) (Middle Tithonian) Association: Chitinoidella dobeni , Ch. tithonica, Ch. s/ovenica, Ch. oolomi, Ch. insueta, Chitinoidella sp. Barlja section Salash Formation (Berriasian-Barremian) Aphanitic and clayey limestones intercalated by marls sharp lithological boundary Glozhene Formation (samples NoNo 0307-331) (38 m) (Middle Tithonian, p.p. -lower part of Berriasian) Grey micritic pelagic limestones. Ca/pione/la Standard Zone (p. p.) (311-331) (21m) (Upper Tithonian-lower part of Berriasian) Calpionel/a elliptica Subzone (p. p.) (326-331) (6 m) (lower part of Berriasian) Calpionellid association: Tintinnopsella carpathica, Cc.lpionella a/pina, Remaniel/a cadischiana, Ca/pionel/a elliptica, Tintinnopsella tonga, Crassicollaria parvula. Remanie/la Subzone (323-325) (3 m) (lower part of Berriasian) Calpionellid association: T. carpathica, C. alpina, Cr. parvula, R. cadischiana. Ca/pionella alp ina Subzone (311-322) (12m) (Upper Tithonian - lower part of Berriasian) Calpionellid association: C. a/pina, T. carpathica, Cr. parvula, Crassicollaria co/omi. Crassicollaria Standard Zone (301-310) (10 m) (Upper Tithonian)
6 Crassicollaria massuflmana Subzone (305-310) (6 m) (Upper Tithonian) Calpionellid association: T. carpathica, C. alpina, Crassicollaria massutiniana, Crassico/laria brevis, Cras sicollaria intermedia, Cr. parvula, homeomorph Calpione/la elliptica. Tintinnopsel/a remanei Subzone (301-304) (4 m) (Upper Tithonian) Calpionellid association : T. carpathica, Cr. intermedia, Cr. massutiniana, T. remanei. Praetintinnopsel!a Zone (0301-300) (2m) (Middle-Upper Tithonian boundary interval) Association: Praetintinnopse/la andrusovi, T. carpathica, Chitinoidella boneti. Chitinoidel/a Zone (p.p.) (0307-0302) (6 m) (Middle Tithonian) Chitinoidel/a boneti Subzone (0306-0302) (5 m) (Middle Tithonian) Association: Chitinoidel/a boneti, Chitinoidella sp. Chitinoidel/a dobeni Subzone (p.p.) (0307) (I m) (Middle Tithonian) Chitinoidella sp. rapid lithological transition Ginci Formation (Middle Tithonian) Grey to pink clayey nodular limestones. Chitinoidella Zone (p.p.) (0308-0310) (3 m) (Middle Tithonian) Chitinoide/la dobeni Subzone (p.p.) (0308-0310) (3 m) (Middle Tithonian) Association: Chitinoidel/a dobeni, Chitinoidella slovenica.
Praecalpionellid and calpionellid biostratigraphy of the Middle Tithonian to Berriasian in W. Balkanides
The calpionellid zonation of the Tithonian - Beriasian interval in the study area is based on the Rome Standard Zones (A II em ann et al., 197l).From the bottom to the top the Chit inoide!a, Praet innopsel/a, Crassicollaria and Ca/pionel/a Zones have been estab lished in both sections and the lower part of the Ca/pionel/opsis Zone has been proved in Komshtica section (Figs. 3, 4). The Chitinoidel/a, Cras sicol/aria and Ca!pione/la Zones have been divided into subzones. The lowest Ca!pionel!opsis simplex Subzone of the Ca/pionel/opsis Zone has also been proved. The praecalpionellid Chitinoidel!a Zone comprises about 10 m thick interval of the ra pid lithological transition between the nodular limestones of Ginci Formarion and the mic ritic limestones of Glozhene Formation. In both sections the boundary between these for mations coincides with the middle-upper part of the Chitinoidella dobeni Subzone, Middle Tithonian. The Crassicollaria Zone has been divided into two subzones according to the subdivi sion proposed at Siimeg Meeting (Rem a n e et al., 1986). A new name, Crassicollaria massutiniana, is here introduced for the upper subzone. The constant although not frequent occurrence of the first representatives of the ge nus Remanie/la Cat a 1an o, 1965 in the middle part of the Ca!pionel/a Zone in the study area of the Western Balkanides has corroborated the triple subdivision of thi s zone into Calpio ne/la a/pina, Remaniel/a and Calpionella elliptica Subzones. The lower boundary of the Re manie/la Subzone is accepted to be very close (a little higher) to the classical Tithonian-Ber riasian boundary at the base of the ammonite Grandis Zone. Thus, the presence of Rema niel!a Subzone in the Southern Mediterranean province (P o p, 1974, 1986; B a k a l o v a -I v a n o v a, 1986; R e m a n e et al., 1986) provides particular biostratigraphic potential in the redefinition of the Jurassic-Cretaceous boundary. The present author fol lows the classical definition to place the Tithonian-Berriasian boundary within the Ca/ pionella Zone at a level a little lower than the base of the Remaniella Subzone. The description of the zones and subzones includes data on the original definition or indication of each unit by previous authors, as well as comments on the type of the bio stratigraphic subdivisions. The zonal (subzonal) association is composed of characteristic species together with species that appear and disappear within and range through the zone (subzone). The chronostratigraphic equivalent of the zones and subzones has been deter mined based on comparison with the same biostratigraphic units which were well-dated and
7 NUMBER OF SPECIMENS: w w w + I - 3 (SINGLE) Fig. 3. Range chart and frequency of the praecalpionellid and calpionellid species in Komshtitza section. The graph on the rightest part shows the total number of specimens in 1 em! of each thin section 8 NUMBER OF SPECIMENS: .... z -~ (!) .... 0 z + I - 3 (SINGLE) ... z oC( .... - .... ~ (!) 0 1- -' I 4 - 10 (RARE) 1- z oC( ll.. ci. oC( N (I) ~ Ul :1:: 0 CD :1:: oC( -~ ~ f.J 'tl I 1 I - 40 (FREQUENT) 1- CD II) -~ .... N :::1 0( ~ ~ ~ .c II) :::1 ~ ~~ - ~ 'tl II) 0 ~ .... ~ .... I 41 - I 00 (COMMON) Ul -~ ~ ~~ ~ ·!:: ... i "S ·"':.: -~'tl .ti, :§ .!:: ~~ ~ a I > 100 (ABUNDANT) :I: ... ~ -~ ~ ~ i~ Ul !i ~I ~~ a l.l~ oC( II ~ 0 100 200 300 400 500 -' G G ~ G~ cc Cf.J c~ c ~f.J 1...; oC( Ul 41 m "" f-- I I I I z ~. «< I I I I oC( ....-~ ...... I I + I I - ~ ...... I + I II) :::: I 'to ..... + + I oC( ...,., f.J + + + l - 1--- ...,., + + 0( ~ .... I 0( ~ .,.,., I I Ul I I ~ ~ ...... I CD ' I I .<::~ ...,, + 1--r--- I ~ 30 ...... I I ~ "''" I I 'tl ..... I I - ~ ..... ~ I I 'tl ..... f.J I I Ul ·~ I I z .... I I Ul ..... :I: I I I N ... ., + 0 0( 1--- "''1 I + UJ ~ -' z ll.. ~ (!) 20 I I I I ll...... oC( + I :::1 ....~ I I + - -~ ~ ...... - I I z .!:! ~ + + I I 0 ' ~ ..... I I I :I: ....a > ... c + I I > ... ~ 1- -...... + I + ~ ~ - I.J ...... + 1- ~ ..,., I ~..-: + I ..... + I I ~~ 10 ...... + tfnnQp I I - ...... I I • ~'/L...... ~ ~ Ul ~ ~ ...... -' ~ ~ .....,.._ 0 "IS ~ +I ' 0 I.J ~ ...tniY. + - .... ~ ...... :1:: ::::: ~ f-- + ~ ~ -00011 + "IS ~ ,...... ~ (.;) I I i 0 I I Fig. 4. Range chart and frequency of the praecalpionellid and calpionellid species in Barlja section. The graph on the rightest part shows the total number of specimens in 1 cm2 of each thin section 9 correlated to ammonite zones in SE France (L e He gar at, Reman e, 1968) and Hungary (H o r vat h, K n au e r, 1986). The Chit inoidella Zone Nomen cIa t u r e. G rand e s so (I 977) introduced and defined "the total-range Chitinoidel/a Zone". It was first mentioned without definition by R e m a n e (I 974, p. 46, fig. 21). B aka l ova (1977) and later A It in e r, 0 z k an (1991) established and des cribed this zone but did not define it. B o r z a (1984) was the first to desribe the Chi tinoidel/a Zone and its microfossil association. De f i n i t i o n and b o u n d a r i e s. This zone represents a total-range zone of the praecalpionellid genus Chitinoidel!a Do ben, 1963. The lower boundary is placed by the appearance of the first small species with microgranular wall of the Chitinoidel/a dobeni group, e. g. Chitinoidel/a dobeni B o r z a, 1966, Ch . colomi B o r z a, 1966, Ch . slo venica B o r z a, 1969 and Ch . tithonica B o r z a, 1969. The upper boundary is placed by the gradual but rapid phylogenie transition from Chitinoidella boneti D o b e n, 1963 to Praetintinnopsel/a andrusovi B o r z a, 1969 with an inner hyaline and outer microgranu Iar wall (see B o r z a, 1969). The Chitinoidel!a Zone is divided into two subzones: a low er, Chitinoidel!a dobeni Subzone, and an upper, Chitinoide!la boneti Subzone (B o r z a, 1984). Z o n a l as s oc i at i o n. It is totally composed of the species of genus Chitinoide/ /a. In the lower part of the zone only small-sized species occur, e. g. Chitinoidel/a dobeni, Ch. colomi, Ch. s/ovenica, Ch. tithonica. Ch. dobeni is the most abundant species. Ch. in sueta R e han e k, 1986 is represented by single specimens (Fig. 3). The middle portion of this zone is characterized by very scarce occurrence of praecalpionellids. In the upper third of the zone only the la rge-sized species Chitinoidel!a boneti occurs which is frequent to rare (Figs. 3, 4). C h r o no s t rat i g rap h i c e q u iva I en t. The Chitinoidel/a Zone corresponds to the Middle Tithonian Substage except the Middle-Upper Tithonian boundary interval. 0 c c u r r en c e. The zone has been established in Komshtica section where it com prises the lowest 5 m of the Glozhene Formation and the highest 5 m of the Ginci For mation (from sample No 0206 to sample No 204) and in Barlja section- the lowest 5 m of the Glozhene Formation and the highest 3 m of the Ginci Formation (from sample No 0310 to sample No 0302). The lower boundary of the zone has not been established in this study. Co r r e I a t i o n s. The same zone was earlier proved in the Middle Tithonian of the Venetian Alps, Italy (G rand e s s o, 1977), NW Anatolia, Turkey (A I t i n e r, Ozkan, 1991 ), W. Carpathians, Slovakia (Borza, 1984; Borz a, Michalik, I 986) and at Ginci section some I 0 km west of the studied region in W Balkanides, Bul garia (B aka I ova, 1977). The Chit inoidella dobeni S u b z o n e Nomen c I at u r e. The subzone was introduced and defined as "dobeni subzone" by Borza (1984). In Bulgaria it has been found for the first time. D e f i n i t i o n a n d b o u n d a r i e s. The Chitinoidel/a dobeni Subzone repre sents a total-range subzone of the index-species which appears at its lower boundary. The upper boundary is characterized by scarcity of Chitinoide/la in a n intermediate level to the overlayi ng Chitinoidel/a boneti Subzone. Sub z o n a I a s soc i at i o n. Chitinoidel/a dobeni, Ch. co/omi, Ch. s/o venica, Ch. ti thonica, Ch . in sueta. Ch. dobeni is frequent to rare whereas all other species are rare to single. 10 C h ron o stratigraphic e qui valent. The lower part of the Middle Ti thonian (see Borza, M i c h a I i k, I986, fig. 6). 0 c cur r en c e. Komshtica section, the highest 5 m of the Ginci Formation and the lowest I m of the Glozhene Formation (0206-020I); Barlja section- the highest 3 m of the Ginci Formation and the first I m of the Giozhene Formation (0310-0307). Co r reI at ion s. The lower part of the Chitinoidel/a Zone in the Venetian Alps with the species of Ch. dobeni group (Grande s so, I977) and 'Dobeni Subzone' in W Carpathians (Borza, 1984; Borza, M i c h a I i k, 1986). The Chit inoidel/a bonet i Sub z one No me n c I at u r e. The subzone was introduced and defined as "boneti subzone" by B o r z a (1984). In Bulgaria it is described for the first time. De f i n i t ion and bound a r i e s. The Chitinoidella boneti Subzone represen ts the acme-zone of the index-species. Its lower boundary is marked by the appearance of Ch. boneti. The upper boundary is defined by the sudden decline of Ch. boneti and the appearance of Praetintinnopsella andrusovi. Sub z o n a I association. The index-species is abundant throughout the subzone. Other large-sized species of Chitinoidel!a have been recorded from this subzone, e. g. Ch. cu bensis (F u r r a z o I a Be r mud e z, 1965) and Ch. bermudezi (F u r r a z o I a Be r m u de z, 1965), in W Carpathians (B o r z a, M i c h a I i k, I986) but in Western Bal kanides only Ch . boneti has been found. In the top of the subzone first single Praetin tinnopsel/a andrusovi may occur as well as transitional forms between Ch. boneti and Pr. an drusovi (Komshtica section, Fig. 3). C h r o n o s t r a t i g r a p h i c e q u i v a I en t. 1 he subzone corresponds to the upper part of the Middle Tithonian and its upper boundary is close to the Middle-Upper Tithonian transition. 0 c c u r r en c e. Komshtica section, the base of the Glozhene Formation, 5 m thick ness (200-204); Barlja section, the base of the G1ozhene Formation, 5 m thickness (0306- 0302). C o r r e I a t i o n s. The "Boneti subzone" in W Carpathians (B o r z a, 1984; B o r z a, M i c hal i k, 1986), the upper portion of the the Chitinoidella Zone in the Venetian Alps (G ran de s so, 1977) and the Chitinoidel/a Zone in N W Anatolia (A I t i n e r, Ozkan, 1991). The Praetintinnopse/la Zone Nomen cIa t u r e. The zone has been introduced as "Praetintinnopsel/a total-range zone" by Grande s so (1977). It is established and described in Bulgaria for the firste time. De f i n i t i on and b o u n d a r i e s. The zone covers the total vertical range of the index-genus. The lower boundary is marked by the transition from Ch. boneti to Pr. an drusovi and the upper boundary is characterized by the next step in the evolution of prae calpionellids and calpionellids, i.e. the transition from Pr. andrusovi to the small forms of Tintinnopsel/a carpathica (M u r g e an u, F i I i p e s c u, 1933) with fully hyaline cal citic wall (see Borza, 1984; Grandesso. 1977 ; Borza, Michalik, 1986). Z on a I a s soc i at ion. Praetintinnopsel/a andrusovi which is usually frequent is the dominant species. In the lower part the last Ch. boneti occur rarely and in the upper part representatives of T. carpathica appear. Thus, sporadic specimens of Ch. boneti may coexist with the first T. carpathica within the Praetintinnopsella Zone as mentioned by B o r z a ( 1984). C h ron o s t rat i graphic e q u i v a I en t. The zone corresponds to the Middle Upper Tithonian boundary interval (Borza, M i c h a I i k, 1986). 0 c c u r r en c e. The zone comprises about 2 m thick interval in the basal part of the Glozhene Formation in both sections (Komshtica- 205-206; Barlja- 0301-300). II Co r r e l at i on s. The Praetintinnopse/la Zone in the Venetian Alps (G rand e s s o, 1977) and in W Carpathians (Borza, 1984; B o r z a, Michalik, 1986). The Crassico/laria Standard Zone Nome n c l at u r e. The zone was introduced as "Zone A" in SE France by Reman e (1963, 1964, 1971). The Crassicol/aria Standard Zone has been defined for the whole W Mediterranean province by A II em ann eta!. (1971). In Bulgaria B aka I ova (1977) proved it for the first time. De f i nit i on and bound a r i e s. According to the original definition "the Crassico/laria zone" is characterized by the obvious predominance of the genus Crassi col/aria R e mane, 1962. The characteristic genus appears immediately above the first occurrence of calpionellids with hyaline calcitic test represented by a small variety of Tin tinnopsel/a carpathica at the very base. Ca/pionel/a alpina appears within this zone and although it may be frequent in the uppermost part of the zone, never predominates over Crassicol/aria (A II e m a n n et al., 1971, p. 1338). The zone is divided into two subzones: a lower, Remanei Subzone, and an upper, lntermedia Subzone (Reman e et al., 1986). In this paper, a new name, Crassicol/aria massutiniana, is proposed for the upper subzone. Zonal as soc i at ion. It is composed of the following species: Tintinnopsel/a carpathica (rare to single throughout the zone); Tintinnopsella remanei (rare to single and restricted to the very base of the zone); Crassico/laria intermedia (D u ran d Del g a, 1958) (frequent in the lower part, frequent to rare in the middle part and absent from the upper part of the zone); Crassicol/aria massutiniana (Colo m, 1948) (usually restric ted to the upper part, frequent to common in the highest part); Crassico/laria brevis R e m an e, 1962 (definitely restricted to the upper part, rare to common); Calpione/la alpina Lorenz, 1902 (the large variety which is restricted to the upper part, common to abun dant); Crassicol/aria parvula R e mane, 1962 (single to frequent at the top of the zone) and a homeomorph of Ca/pionel/a el/iptica C a d i s c h, 1962 (single to frequent at the top of the zone) (see Figs. 3, 4). On the base of its taxonimic content and relative abundance of species the zone can be clearly divided into two parts: a lower one, with predominance of Cr. intermedia (the "Remanei Subzone"), and an upper one, with diversity of genus Cras sico/laria and usually predominance of the large variety of C. a/pina and frequent presence of Cr. massutiniana and Cr. brevis (the "lntermedia Subzone" sensu R e m a n e et al., 1986. At the top of the zone Cr. massutiniana, Cr. brevis and the homeomorph of C. el liptica disappear. This event is sinchronous with the rapid transition from large elonga ted to medium-sized sphaerical variety of C. alpina and a decrease in the total number of specimens. This study has not confirmed a number of the originally defined and wide ly accepted features of the Crassicol!aria Zone. For example, Cr. intermedia attains its maximum development in the lower part of the zone whereas in the upper part it is rare to absent. C. a/pina usually predominates over Crassicol/aria in the upper part of the zone. Once appeared, C. a/pina becomes frequent to abundant and represents more than 50% of the total fauna (Figs. 5, 6). C h ron o stratigraphic e qui valent. The Crassicol/aria Standard Zone corresponds to the Upper Tithonian but not to its highest part (L e He gar at, R e m an e, 1968, p. 58). 0 c cur r en c e. Komshtica, lower part of the Glozhene Formation, 12 m (207- 218); Barlja, lower part of the Glozhene Formation, 10 m (301-310). Co r relation s. The Crassicol/aria Zone in S Carpathians, Romania (Pop, 1974; 1986), Mexico (T r e j o, 1980), Cuba (P o p, 1976), W Carpathians (B o r z a, 1984; Borza, Michalik, 1986); NW Anatolia (Altiner, Ozkan, 1991) and W Balkanides (B aka I ova, 1977) ; the Zone A in SE France (Reman e, 1971); the "Crassicol/aria intermedia Zone" in Spain sensu A II em ann et al. (1975) and in Si cily sensu Catalano, Liguori (1971). 12 T h e Tint innopse//a remanei S u b z o n e Nomen cIa t u r e. This subzone was introduced as "Subzone A I" by Reman e (1971). It was defined a s standard "Remanei Subzone" for the Mediterranean region by Reman e et al. (1986). In Bulgaria it is established for the first time. De f i n it i o n a n d b o u n d a r i e s. The lower boundary is marked by the appea rance of Crassico/laria intermedia, Tintinnopsella remanei and of typical T. carpathica. The upper boundary which is the lower boundary of the overlying subzone is defined by the first occurrence of C. a/pina. Thus, it is the interval-subzone between the appearance of the first calpionellids with hyaline wall and the appearance of C. alpina. Tintinnopsel/a remanei B o r z a, 1969 is the index-species. Sub z on a 1 a s soc i at i on. T. remanei is restricted to the base of the subzone and is single to rare. T. carpathica is single to rare throughout the subzone. The first single specimens of T. carpathica which are not typical and represent a transition from Pr. andrusovi occur in the underlying Praetintinnopsel/a Zone. Crassicollaria intermedia is the dominant species and is usually frequent. Crassicol/aria massutiana appears at the top of the subzone and is rare. Similarly to the preceding praecalpionellid Chitinoidella and Praetintinnopsel/a Zones the total number of the specimens counted in I cm2 of each thin section is usually less than 50 within the T. remanei Subzone. C h ron o s t rat i g rap hi c e qui v a I en t. The lower part of the Upper Ti thonian. 0 c cur r en c e. Komshtica section, 6 m of the lower part of the Giozhene For mation (207-212); Barlja section, 4 m of the lower part of the Glozhene Formation (301- 304). Co r r e 1 at ions. According to Reman e et al. (1986) this subzone equals per fectly to A I Subzone in SE France (Reman e, 1963, 1964). On the basis of definition of its boundaries the 'Subzone A I' of the Crassicol/aria Zone in NW Anatolia (A It i n e r, 0 z k an, 1991) also correlates with the T. remanei subzone. Pop, Me 1 in t e (1992) have mentioned "the Remanei subzone" of the Crassicollaria Zone in S Carpathians. The Crassiol/aria massutiniana Subzone N o m e n c 1 a t u r e. The subzone is introduced in the present paper. The index-species is Crassicol/aria massutiniana (Co I om, 1948). De f i n i t i o n a 11 d b o u 11 d a r i e s. The lower boundary is marked by the appea rance of the large variety of Ca!pionel/a a/pina and the upper boundary is the same as the lower boundary of the Ca!pionella Standard Zone. The subzone is characterized by diversity of the genus Crassicol!aria. By intent of its definition the newly proposed Cras sico!/aria massutiniana Subzone is equal to the "Jntermedia Subzone" sensu Reman e et al. (1986). The new name is here proposed for two reasons: 1) Crassicol/aria massuti niana is frequent to common and usually restricted to this subzone whereas Crassicol!a ria intermedia occurs rarely only at the base of the subzone and is much more charac teristic of the underlying T. remanei Subzone. 2) Pop (1974) has established the Crassicol /aria intermedia Subzone in S Carpathians which represents the lower half of the Crassi col!aria Standard Zone (Fig. 2). Consequently, the "Jntermedia Subzone" in the upper part of the Crassicollaria Zone sensu Reman e et al. (1986) represents a different biostra tigraphic unit and it is a junior homonym which should be abandoned in order to avoid confusions. Sub z o n a 1 a s soc i at i on. T. carpathica (single to rare), Cr. intermedia (fre quent to rare, at the base of the subzone only), Crassicol!aria brevis (restricted to this subzone, usually common in the middle part). Cr. massutiniana appears a little lower than the base of the subzone and disappears at the upper boundary. This species is usually frequent and in one case it is dominant (Komshtica section, Fig. 5, sample 216). Calpio ne!la alpina (large variety) appears at the base of the subzone and is the predominant 13 species (Figs. 5, 6). In the upper part of the subzone the large variety of C. alpina is quickly replaced by the medium-sized sphaerical variety. Crassico/laria parvu/a appears at the upper part and is of rare occurrence. At the top of the subzone a homeomorph of Calpionel/a elliptica exists at a short time interval. There is an obvious increase in the total number of the calpionellid specimens at the lower boundary of the subzone. C h ron o stratigraphic e qui v a 1 en t. Upper Tithonian. 0 c c u r r en c e. Komshtica section, 6 m of the lower part of the Glozhene For mation (213-218); Barlja section, 6 m of the lower part of the Glozhene Formation (305- 310). Co r r e l at i on s. The "Intermedia Subzone" in Reman e et al. (1986) is per fectly equal to this subzone. The Crassicollaria massutiniana Subzone corresponds to the subzones A2 + A3 of Remane (1963, 1964), A2 + A3 of Altiner, Ozk an (1991) and correlates with the Crassicol/aria brevis- Crassicol/aria parvula Subzone in S Carpa thians (Po p, 1974). T h e Calpionella Standard Z o n e No me n c l a t u r e. The Ca/pionel/a Standard Zone has been introduced and defined for theW Mediterranean province by Allemann et al. (1971). Bakalova (l977)pro ved it for the first time in Bulgaria. The genus Calpionel/a L o r en z, 1901 is the index taxon. D e f i n i t i o n a n d b o u n d a r i e s. In the original definition the Ca/pionella Zone has been characterized by the predominance of genus Calpionel/a. A 11 e m a n n et al. (1971), however, have noticed that it is valid for the lower part only. This study has con firmed that at the top of the zone T. carpathica predominates over C. alpina (Figs. 5, 6). It is widely accepted that the lower boundary of the Calpionel/a Zone is defined by the rapid morphological change from the large elongated to medium-sized sphaerical variety of C. a/pina and by the increase in relative abundance of this species which may attain over 90% of the total fauna (B o r z a, 1984; Reman e, 1986; R e mane et al., 1986). The upper boundary of the Calpionel!a Zone which is the lower boundary of the Ca/ pionel!opsis Zone is placed at the first occurrence of Calpione/lopsis simplex (Colo m, 1939). Thus, the Ca!pionel/a Zone represents an interval-zone restricted between these two biostratigraphic markers. Following the subdivision proposed by Pop (1974) three sub zones have been defined in the Calpionella Zone: the Calpionel/a a/pina, Remanie/la and Calpionel/a elliptica Subzones. Z o n a l a s s o c i a t i o n. Ca/pionel/a alpina and Tintinnopsella carpathica occur throughout the zone. C. a/pina is usually abundant except in the upper third whereas T. carpathica is frequent to rare (Figs. 3, 4). Crassicollaria parvu/a is the only represen tative of the genus Crassicollaria which ranges from the underlying zone. This species is frequent to rare in the lower and middle part and di sappears in the upper part. Cras sicol/aria co/omi Do ben, 1963 is restricted within a level a little higher than the base of the zone. In the upper part Remaniel!a cadischiana (Colo m, 1948), Ca!pione/la ellip tica and Tintinnopsel/a /onga (Co I o m, 1939) appear one after another. C. el/iptica is frequent to rare, R. cadischiana and T. tonga are rare to single (Figs. 3, 4). C. alpina is obviously the predominant species throughout the zone in exception of its uppermost part where both the absolute frequency and relative abundance of this species decrease abrupt ly. The total number of the calpionellid specimens increases significantly in the lower part of the zone to attain its maximum for the whole Middle Tithonian-Berriasian interval and decreases gradually to the top. C h ron o s tratigr aph ic e qui v a I en t. Upper part of the Upper Tithonian -lower part of Berriasian. The classical Jurassic-Cretaceous boundary between the ammo nite ''jacobi" and "grandis" Zones is placed within the Calpionella Zone (the zone B in L e H e g a r a t, R e m a n e, 1968). 14 "T'' ~ - T IT H O NIAN l B E R R I ASIAN I ST A G E !-" MIDDLE j _____ UPPER j ! SUB S TAGE ::0 (> Clllpianelle Z 0 N E E C./I. dtJbilnl C. 11/pine s u B z o N E I <'(> G!NCI GLOZHENE OR M ATION ~ a 0 c t:l 0.. ~ t:l n0 0.., ;. (> "0 "'(> ;;·0 "'5 ' "0 (> "'1 0 (> ::l j;; OQ "'0...., 0 E t.i' c ::l ~ 0 0 5' M ~ 111 0 FSJ&WTi nmmnnRD~II 111 D 3 LdfJBmJLJ ~ illillJLJ . ~ R . . . "TlC) "TlCl -,U1 0 .. ~ ::r , '1 '1 ~ ~ ~ ::?:"' 0 - 0 - ~ ,., ~ ~ ~ 0 :;> . .., .... 3 ~ 3 ~ ~ .. '::. 3 "' ·~ ;::; .. ::r 3 ~ ~ il ,.. "' :;) .. "' .. -· ;~ ~ ~ ~ ~ 5' ,. ~ !;> s ~ ~~ .. ~ ;-:; c;· ~ ·~ · ~ 0 .. 0 "' ·~ ~ "".. :1: ~ ~ ~ ;g ~ ~ ·~ · ~ ~ ~ ~ "' "' "' "' " ~ - ' · ~ ~ ~ ~ ~ :1:. l ,. ~ · a(5 ' .. ... ~- ~ .. 'C"' ~ - ::l '? ~ Vl- z ...... 0 (:1 ...... : ... z - (:1 z 0 1- 1- N ...: U) ...: 0 a:l I: a:l 1- N :::1 a.: :::1 U) U) 0 U) ... :J: U) ...: ...J z ...: (f) 41m ...: 1-- - ..._a •II) ...... : · ~ - ~ (.,$ ~ a.: ... ~ a:l ~ ~ mJ Cr col omi ~ - Ci: f.-- - ~ ~ hom. c elltPii o ~ 30 ~ · ~ ~.. (.,$ c::IJ C 4/pin4 ..... z ..... :J: EJ Cr. /lrtwis N a.: 0 ~ ... ~ ...J z Q. ~ (!I Q. ~~ ...: :::1 .... - · ~ ~ .... ~ Cr. intermP.di6 ~ ...... z ~ ~ 0 ~ .... ~ :J: a.... _g_ 1- .... - ~ ·~ 1- ~ ' 10 1--figJJ ;1-1~ Pr. tmdrusovi ~M_ ...... 'l; .fu~:11 H ChitinOidel/4 spp. ...J ~ ~ 0 0 ~ G - · ~ - Selesh I: ....· ~ .ir- Formetion ;s ~u 'iiZ Glozhene ,.,; G Formation 0 0 10 20 _30 40 ~0 60 70 60 90 1001 W::J Ginci Forme lion Fig. 6. Relative abundance of the species in percentage of the fauna in Barlja section 16 0 c c u r r e n c e. The Ca/pionel/a Zone corresponds to the upper half of the Glozhe ne Formation. Its thickness is 25 m in Komshtica section (219-243) and 21 m in Bar lja section (311-331). Co r r e 1 at i o n s. The Calpionel/a Standard Zone has been proved in S Carpathians (Pop, 1974, 1986), W Carpathians (Borza, 1984; Borza, Micka I i k, 1986), NW Anatolia (A 1 tine r, 0 z k an, 1991), Cuba (Pop, 1976) and W Balkanides (B a ka 1 ova, 1977). It is equal to the zones B+ C in SE France (L e He gar at, Rem a n e, 1968) and B+ C (Ca/pionel/a a/pina+ Ca/pionel/a el/iptica Zones) in Central Hungary (Horvath, Knauer, 1986),Sicily (Catalano, Liguori, 1971)andSpain (Al leman n et al., 1975). The Ca/pionel/a Zone and Ca/pionel/a e/liptica Subzone (p. p.) in Mexico (T r e j o, 1980) also correlate with the Calpionel/a Standard Zone (Fig. 2). The Ca/pionel/a a/pina Sub z o n e No men c I a t u r e. It was introduced and defined as "Ca/pionel/a alpina Subzone" by Pop (1974). Earlier, Cat a 1 an o, Liguori (1971) established the "Calpionel/a a/ pina Zone" but it comprises both the Ca/pionel/a a/pina and Remaniel/a Subzones as defi ned by Pop (1974) andRe mane et al. (1986). In Bulgaria this subzone was proved by B aka 1 ova-Ivan ova (1986). The index-species is Ca/pione/la alpina Lorenz, 1902. De f i n i t i o n a n d b o u n d a r i e s. According to its original definition the Cal pionel/a alpina Subzone is an interval-subzone between the "explosion" of C. a/pina and the first appearance of representatives of the genus Remaniella (P o p, 1974, p. 118). The index-species attains its maximum development within this subzone. The lower boundary of this subzone is the same as the lower boundary of the Calpionel/a Standard Zone and the upper boundary represents the lower boundary of the overlying Remaniella Subzone (Reman e et al., 1986). This subzone should not be confused to the "Ca/pionella a/pina Zone" in Sicily sensu Cat a Ian o, Liguori (1971) and the "Calpionel/a a/pina Zone" in Spain sensu Alleman n et al. (1975). The Ca/pione/la a/pina Subzone as defined by Pop (1974) has the same lower boundary with the Sicilian and Spanish zones (i.e. the Crassicol!aria-Calpionel/a boundary) but covers much more restricted stratigraphical in terval (Fig. 2). Sub zona I a s soc i at ion. Calpionel/a a/pina, Tintinnopsel/a carpathica and Cras sicol!aria parvula occur throughout the subzone whereas Crassicol/aria co/omi is confined to its lower part. C. a!pina is usually abundant (Fig. 3, 4) and represents 73 to 95 % of the total fauna in Komshtica section (Fig. 5) and 67 to 94% of the fauna in Barlja sec tion (Fig. 6). T. carpathica is rare to frequent, Cr. parvu/a is frequent to rare, someti mes common, and Cr. colomi is frequent to single. The latter species has not been re corded from the Crassicollaria Zone in this study. As it has been established earlier by Borza (1984, table l), Cr. co/omi may occur together with Cr. parvu/a but it appears after the disappearance of Cr. massutiniana and Cr. brevis and after the morphological change in C. a/pina. The total number of the calpionellids increases considerably and at tains its maximum within this subzone. C h ron o s t rat i graphic e qui v a lent. The uppermost part of the Upper Tithonian and the very base of the Berriasian based on parallel finds of calpionellids and ammonites (see Le Hegarat, Remane, 1968; Horvath, Knauer, 1986). In SE France and Hungary the first representatives of Remaniel/a appear a little higher than the boundary between the ammonite ''jacobi" and "grandis" Zones. 0 c cur r en c e. Middle part of the Glozhene Formation: Komshtica, 16 m (219- 234); Barlja, 12 m (311-322). Co r r e 1 at ion s. The C. alpina Subzone in this study is equal with the same sub zone established by Pop (1974, 1986) in S Carpathians, Pop (1976) in Cuba and B aka 1 ova-Ivan ova (1986) in W Bulgaria. The lower parts of the "Ca/pionel/a al pina Zone" in Sicily (Cat a Ian o, Liguori, 1971) and Spain (A II em ann et al., 2 Geologica Balcanica, 23. 6 17 1975) correlate with the C. a/pina Subzone. The lower parts of the Zone B in SE France (Reman e, 1971), Zone Bin Hungary (Horvath, Knauer, 1986), Zone Bin NW Anatolia (Altiner, Ozkan, 1991) and "Calpionel/a Zone" inMexico(Trejo, 1980) are also correlatives (Fig. 2) T h e Remaniella S u b z o n e No men cIa t u r e. The Remaniel/a Subzone was originally defined by Pop (1974) and proved for the first time in this country by B aka I ova-Ivan ova (1986). De fin it ion and boundarie s. It is an interval-zone between the first appea rance of representatives of the genus Remaniel/a (the lower boundary) and the sudden increase in the relative abundance of typical specimens of Calpionel/a e/liptica (the upper boundary) according to Pop (1974). Later, Reman e et al. (1986) redefined the up per boundary and placed it at the first appearance of typical C. el/iptica. The last crite rion has been accepted in this study. Sub zona I association. C. a/pina (abundant to frequent), T. ca rpathica (frequent to single), Cr. parvu!a (usually frequent) and Remaniella cadischiana (single to rare). The total number of the calpionellids is much lower than in the C. a/pina Subzone. C h r o n o s t rat i g rap h i c e qui v a I e n t. The base of the Berriasian (R e m an e et al., 1986, p. 9). 0 c cur r en c e. This subzone covers 3 m thick interval in the upper part of the G!ozhene Formation in both Komshtica section (235-237) and Barlja section (323-325). CorreIa t ions. The Remaniel/a Subzone in S Carpathians (Pop, 1974, 1986), Cuba (Po p, 1976) and W Bulgaria (B a k a I o v a-Ivan o v a, 1986); the upper part of the Zone Bin SE France (Reman e, 1971), Central Hungary (Horvath, Knauer, 1986) and NW Anatolia (A It in e r, 0 z k an, 1991); the upper part of the "Ca/pionel/a alp ina Zone" in Spain sensu A II e m a n n et al. (1975). T h e Calpionel/a el/iptica S u b z o n e Nomenclature. Catalano, Liguori (1971) introduced it as "Calpionel!a e/ liptica Zone". Later, Pop (1974) redefined it as "Ca/pionel/a el/iptica Subzone" which is equal to the Catalano and Liguori's unit and represents the upper (third) subzone of the Calpionel/a Standard Zone. In Bulgaria it was proved by B aka I ova-Ivan ova (I 986). Ca!pionel/a elliptica Cadi s c h, 1932 is the index-species. De f i n i t i o n and b o u n d a r i e s. The lower boundary is defined by the ap pearance of typic<~l Calpionel!a e/liptica and the upper boundary is marked by the appea rance of Calpionel!opsis simplex. It is an interval-subzone which is above theRemaniel/a Subzone and below the Calpionel!opsis Standard Zone. Sub zona I association. C. a/pina (abundant to rare), T. carpathica (single to frequent) and Remaniel!a cadischiana (single to rare) occur throughout this subzone. C. el/iptica (frequent to single) appears and Cr. parvula (frequent to single) disappears at the base. In the middle part Tintinnopse/la /onga appears (single to rare). The relative abundance of C. alpina decreases suddenly in the upper half of the subzone where T. car pathica (the large form), C. e/iptica and T. /onga represent greater part of the calpionel lids. The significant decrease in the total number of specimens within the C. elliptica Sub zone reflects the decline of C. alpina. C h r o n o s t r a t i g r a ph i c e q u i v a 1 en t. Lower part of the Berriasian (P o p, 1974). 0 c c u r r e n c e. The subzone covers 6 m thick interval in the top of the Glozhene Formation in Barlja section (326-331) and 6 m thick interval of the upper part of the Glozhene Formation in Komshtica section (238-243). Co r reI at i on s. The C. el/iptica Subzone in this study is equal to the " Ca!pione/ /a el!iptica Zone" in Sicily (Catalano, Liguori, 1971), the "Ca/pionel/a el/iptica Zone" in Spain (A II em ann et al., 1975) and the C. elliptica Subzone inS Carpathians (Pop, 18 1974, 1986), Cuba (Pop, 1976) and W Bulgaria (Bakalova-Ivanova, 1986) The Zone C (Tintinnopsella) in SE France (L e He gar at, Reman e, 1968) and Zone C in NW Anatolia (A It in e r, 0 z k an, 1991) also correlate with this subzone. T h e Ca/pionellopsis S tan d a r d Z o n e No me n cIa t u r e. It was introduced as Zone D in SE France by Reman e (L e He gar at, Reman e, 1968). The Ca/pione/lopsis Standard Zone was established and defined by A II em ann et al. (1971). In Bulgaria it was proved by B aka I ova (1977). The genus Ca/pionel/opsis Co I om (sensu Reman e, 1965) is the index-taxon. De f i n i t i o n a n d bound a r i e s. The Ca/pione/lopsis Standard Zone is origi nally defined by A II em ann et al. (1971) as an interval-zone between the first occur rence of Calpione//opsis simplex and the first occurrence of Calpionel/ites darderi (Colo m, 1934). The zone is divided into two standard Mediterranean subzones: a lower, Calpionel /opsis simplex, and an upper, Calpionel/opsis ob/onga (R e m an e et al., 1986). Only the lower part of this zone has been established in this study. Z o n a I a s soc i at i o n. C. a/pina (frequent to rare), T. carpathica (frequent), C. e!liptica, T. tonga and C. simplex (single to rare) and R. cadischiana (single). T. car pathica is the dominant species. C h ron o stratigraphic e qui v a 1 en t. Upper part of Berriasian and the basal part of the Valanginian (L e He g a rat, R e mane, 1968; Pop, 1974). 0 c c u r r en c e. The highest 4 m of the Glozhene Formation in Komshtica section (244-247) represent only the base of the zone. Cor relations. The Zone D in SE France (L e He gar at, Reman e, 1968) and the Zone D (Calpione//opsis) in NW Anatolia (A l tine r, 0 z k an, 1991); the Cal pione//opsis Zone in S Carpathians (Pop, 1974, 1986), W Carpathians (Borza, 1984), Spain (A II em ann et al., 1975), Cuba (Pop, 1976) and W Balkanides (B aka 1 ova, 1977); the Ca/pionel/opsis simp/ex-Calpione//opsis oblonga Zone in Sicily (Cat a Ian o, Liguori, 1971). T h e Calpionellopsis simplex Subzone No me n c l at u r e. It was introduced as the Subzone D l by Remane (L e He g a r a t, R e m a n e, 1968). The Ca/pionellopsis simplex Subzone was established and defi ned by Po p ( 1976). Calpione!lopsis simplex (Co I o m, 1939) is the index-species. In Bulgaria the subzone is found for the first time. De f i n it i o n and bound a r i e s. According to Remane (L c He g a rat, Reman e, 1968) the Subzone D I is characterized by the maximum development of C. sim plex. The C. simplex Subzone is an interval-subzone between two biostratigraphic markers -the lower boundary is defined by the first occurrence of the genus Calpionellopsis Co- 1 o m, 1948 (the species C. simplex) and the upper boundary represents a level of the sudden increase in the abundance of Calpione/lopsis oblonga (see Pop, 1976). Later, Rem an e et al. (1986) and Pop (1986) redefined the upper boundary of the C. sim plex Subzone (i.e. the lower boundary of the C. ob!onga Subzone) and placed it at the first appearance of C. oblonga. In W Balkanides (this study) only the lower boundary of the subzone has been found. S u b z o n a I a s s o c i at i o n. T. carpathica (frequent), C. alpina (frequent to ra re), C. e/liptica, T. tonga and C. simplex (rare to single) and R. cadischiana (single). T. car pathica and C. a/pina are the most abundant species, T. carpathica predominating over C. a/pina. The total number of the calpionellids is lower than in the C. el/iptica Subzone (Fig. 3). C h ron o stratigraphic e qui v a I en t. Upper part of the Berriasian (L e Hegarat, Remane, 1968 ; Zeiss, 1986). 0 c c u r r en c e. The highest 4 m of the Glozhene Formation in Komshtica section (244-247) which represent the lower part of the subzone. 19 N 0 TITHONIAN I BERRIASIAN S T A G !: I MIDDLE I UPPER I SUBSTAGE Chitinoidella Praetin- Crassicollaria Calpionella Calpiopnellopsis Z 0 N E tinnop- SUBZONE Ch. dobeni Ch. boneti <•II; T.remanei 'r.massut. C. aloina emaniella C. elliotica C. simolex - Chitinoidella insueta -- Chitinoidella colomi --- Chitinoidella slovenica -- Chitinoidella tithonica Chitinoidella dobeni Chitinoidella boneti Praetintinnopsella andrusovi - Tmtinnopsel/a remanet - Tintinnopsella carpathica Crassicollaria intermedia Crassicollaria massutiniana Crassicollaria brevis Calpionella alpina Qasstcol_laria _l)arvula - homeomorph Calpionella elliptica -- Crassicollaria colomi Remaniella cadischiana Caloionella elljp_tica Tintinnopsella longa Calpionellopsis simplex Fig. 7. Praecalpionellid and calpionellid zones and subzones and summarized range chart of the species in W. Balkanides, Bulgaria C o r r e 1 a t i o n s. The Subzone D I in SE France (L e H e g a r a t, R c m a n e, 1968), Central Hungary (H o r vat h, K n au e r, 1986) and NW Anatolia (A It in e r, 0 z k an, 1991); the Calpionel/opsis simplex Subzone in Cuba (Pop, 1976) and S Car pathians (Pop, 1986); the Simplex Subzone (Reman e et al. , 1986); the lower part of the Ca/pionellopsis Standard Zone in W Carpathians (B o r z a, 1984) and W Balka nides (B a k a I ova, I 977); the lower part of the C. simplex-C. oblonga Zone in Sicily (Cat a Ian o, L i guo r i, 1971); the lower part of the C. simplex Subzone in Spain sensu A II em ann et al. (1975) (Fig. 2). Conclusions This study has proved that the praecalpionellid Chitinoidella and Praetintinnopsella Zones and the Crassicollaria, Calpionella and Calpione!lopsis Standard Zones in Western Balka nides are very similar or equal to the well-known zones of the same name in the Me diterranean region. The subzonal units of the Crassico!laria, Calpionel/a and Calpione/lop sis Zones proposed at Siimeg Meeting and considered to be standard for the Mediterra nean region have also been established in the study area. The T. remanei, Cr. massuti niana, C. alpina, Remaniella, C. el!iptica and C. simplex Subzones have been recognized, the Cr. massutiniana Subzone being a new name proposed by the present author instead of"Jntermedia Subzone" sensu Reman e et al. (1986) for the upper subzone of the Cras sicol/aria Standard Zone. The Chitinoidella Zone is divided into two subzones, the lower Ch. dobeni and the upper Ch . boneti. Although the definitions and boundaries of all the zones and subzones here descri bed are equal to those of the same biostratigraphic units earlier established in the Me diterranean region, the stratigraphic range and abundance of some species in W Balkani des have shown their specific features. The boundary interval between the Chitinoidel!a dobeni and Chitinoidella boneti Sub zones is characterized by scarcity of praecalpionellids. Single specimens of Ch. boneti may occur in the overlying Praetintinnopsel/a Zone. First rare representatives of the cal pionellids with hyaline calcitic wall (the sm:tll variety of T. carpathica) appear in the Prae tintinnopse/la Zone (Fig. 7). The base of both the Crassicol/aria Zone and T. remanei Subzone is characterized by an association composed of T. carpathica, T. remanei and Cr. intermedia. Cr. interme dia is cha racteristic and usually predominant in the T. remanei Subzone. C. alpina is frequent to abundant throughout the Cr. massutiniana Subzone and usual ly predominates over Crassicol/aria. Cr. brevis is restricted within the Cr. massutiniana Subzone. Cr. intermedia is almost absent from this subzone except its base. Together with the morphological transition from the large elongated to medium-sized sphaerical variety of C. alpina, the disappearances at the same level of Cr. massutiniana and the homeomorph of C. elliptica are additional criteria to establish the boundary bet ween the Crassico/laria and Calpionella Standard Zones. The so-called "explosion" of C. alpina at the same boundary is relatively not clearly demonstrated in the study area. In Komshtica section the relative abundance of C. alpina increases from 68 to 91 % (Fig. 5) and in Barlja section it increases from 80 to 92 % across the Crassico/laria-Calpionella boun dary (Fig. 6). Cr. colomi is restricted to the lower part of the C. alpina Subzone at some 2-3 m above its base. Cr. parvula disappears in the lower part of the C. e/liptica Subzone. The total number of the specimens is low (le ss than 50 in I cm2 of a thin section) within the Chitinoidella and Praetintinnopse/la Zones and T. remanei Subzone (Figs. 3, 4). The appearance and abundant presence of C. a/pina is reflected in a considerable increase of the calpionellids in the Cr. massutiniana Subzone. The boundary between the Crassi col/aria and Calpionella Zones is characterized by a significant quantitative decreasing of the calpionellids. The total number of specimens, however, raises suddenly and attains its 21 maximum within the C. alpina Subzone. Two successive decreasings of the calpionellids have been established higher in the sections, the first one, below the base of the Rema niel/a Subzone, and the second one, in the lower part of the C. el/iptica Subzone. The biostratigraphic data on calpionellids have proved that the Glozhene Formation is of Middle Tithonian to Berriasian age in the study area. The boundary between the Ginci and Glozhene Formations is within the Ch. dobeni Subzone, Middle Tithonian. Further investigation of the calpionellid occurrence in the Berriasian and Valanginian is needed to specify the spatial-temporal relationships between the different carbonate for mations of the Upper Jurassic and Lower Cretaceous in the Western Balkanides. Acknowledgements. I am grateful to Dr I. Sapunov and Dr P. Tchoumatchenco, Geological Institute, Sofia, for introducing me in the Upper Jurassic lithostratigraphy of West Bulgaria, for the joint field work and for cri tically reading the manuscript. I should like to thank Dr D . Bakalova for providing me with literature on cal pionellids. Dr V. Mladenova is thanked for consulting me in computer drawing and Mrs L. Panova is than ked for printing the photographs. This report was supported by the Federal Ministry of Science and Research, contract GZ. 45. 134 under the auspices of the Austrian Academy of Science. References A 11 em ann, F., Cat a Ian o, R., Fares, F., Reman e, J. 1971. Standard calpionellid zonation (Upper Tithonian - Valanginian) of the Western Mediterranean province. - Proc. II Plankt. Conf, Roma I970, 2; 1337-1340. A 11 e m a n n, F., G r ii n, W., W i e d m a n n, L. 1975. The Berriasian of Caravaca (Prov. of Murcia) in the subbetic zone of Spain and its importance for defining this stage and the Jurassic-Cre taceous boundary. - Coil. limite Jurassique-Cretace, Lyon, Neuchlitel I973. Mem. Bur. Rech. Geol. Min. , 86; 14-22. A It in e r, D., 6 z k an, S. 1991. Calpionellid zonation in North-Western Anatolia (Turkey) and ca libration of the stratigraphic ranges of some benthic foraminifers at the Jurassic-Cretaceous boundary. - Geologica Romana, 27; 215-235. B a k a I ova, D . I 977. La succession a Calpionelles de Ia coupe pres du village de Ginci, Bulgarie du Nord-Ouest. - C. R. Acad. bulg. Sci. , 30, 3; 423-426. B aka I ova-Ivan ova, D. 1986. Peculiarities of the Calpionella Zone in Bulgaria. - Acta Geol, Hungarica, 29 (1-2); 89-92. Borza, K. 1966. Neue Arten der Gattung Chitinoidel/a Do ben, 1962 in den Westkarpaten. - Geo/. sbornik, 17, 2; 259-263. B o r z a, K. 1969. Die Mikrofazies und Mikrofossi/ien des Oberjuras und der Unterkreide der Klippenzone der Westkarpaten. Vydav. S1ov. Akad. Vied., Bratislava, 301 p. B o r z a, K. 1984. The Upper Jurassic - Lower Cretaceous parabiostratigraphic scale on the basis of Tintinninae, Cadosinidae, Stomiosphaeridae, Calcisphaerulidae and other microfossils from the West Carpathians. - Geol. Zborn. Geol. Carp., 35, 5; 539-550. Borza, K., M i c h a I i k, J. 1986. Problems with delimitation of the Jurassic I Cretaceous boundary in the Western Carpathians. - Acta Ceo/. Hungarica, 29 (1-2); 133-149. C a t a I a n o, R., L i g u o r i, V. I 971. Facies a calpionelle della Sicilia occidentale. - Proc. II Plankt. Conf, Roma I970, 1, 167-210. Geological Map of Bulgaria M I :500 000. 1989. Cheshitev, G., Kancev, I. (Eds.). Committee of Geology, Department of Geophysical Prospecting and Geological Mapping, Sofia. G rand e s so, P. 1977. Gli strati a precalpionellidi del Titoniano e i !oro rapporti con il Rosso Am monitico Veneto.- Memoire di Scienze Geologiche, 32; 1-14. Horvath, A., Knauer, J. 1986. Biostratigraphy of the Jurassic-Cretaceous boundary beds in the pro file Kozokut Ravine II at Harskut. - Acta Geo/. Hungarica, 29 (1-2); 65-87. L e He g a rat, G., Reman e, J. 1968. Tithonique superieur et Berriasien de Ia bordure cevenole. Cor relation des Ammonites at des Calpionelles. - Geobios, 1, I; 7-70. N i k o I o v, T. 1969. Le Cretace inferieur en Bulgarie.- Bull. Soc. geol. France, (7). 11; 1; 56-68. Pop, G . 1974. Les zones des Calpionellides tithonique-valanginiens du silon de Resita (Carpates meridiona les). - Rev. romaine Geol .. Geophys. et Geogr., Geologie, 18; 109-125. Pop, G. 1976. Tithonian-Valanginian calpionellid zones from Cuba. - Dari seama Sedint. Ins/. Geol. Geo fiz., 62 (3, 4), 237-266. Pop, G. 1986. Calpionellids and correlation of the Tithonian-Valanginian Formations.- Acta Geol. Hun garica, 29 (1-2); 93-102. Pop, G., Me I in t e, M. 1992. Correlation of calpionellid and nannofosil biozones in Tithonian-Neocomian deposits of the South Carpathians.- UNESCO Sixth Annual Meeting. Cretaceous facies in Oro genic Belts, 22-26 May 1992 (Greece). Sixth Congr. Geol. Soc. Greece, Abstracts, pp. 17-18, Athens. R e han e k, J. 1986. Chitinoidella insueta, n. sp. (Protozoa incertae sedis) from the Tithonian of Southern Moravia. - Cas. miner. geol., 31, 3; 287-292. 22 Reman e. J . 1962. Zur Calpionellen-Systematik. - N. Jb. Geol. Paliiont., Mh. I, 8-24. R e m a n e, J. I 963. Les calpionelles dans les couches de passage Jurassique-Cretace de Ia fosse vocontienne. Trav. Lab. Geol. Fac. Sci., Univ. Grenoble, 39; 25-82. Reman e, J. 1964. Untersuchungen zur Systematik und Stratigraphie der Calpionellen in den Jura-Kreide Grenzschichten des Vocontischen Troges. - Palaeontographica A , 123, 1-57. Rem a n e, J. 1969. Les possibilites actuelles pour une utilisation stratigraphique des calpionelles (Protozoa incertae sedis, Ciliata?). - Proc. I Plankt. Conf, Geneva 1967, 2, 559-573. Brill, Leiden. Reman e, J. 1971 . Les Calpionelles, Protozoaires planctonique, des mers mesogeennes de l'epoque secon daire. - Annates Gueblzard, 47; 369-432. Reman e, 1974. Cours de III cycle en Sciences de Ia Terre, Paleonto/ogie, Universite de Geneve. Partie II, Les Calpionelles, 58 p. Reman e, 1985. Calpionellids. In: Plankton Stratigraphy (Bolli, H . M . et al., Eds.), Cambridge Univ. Press, 555-572. Cambridge. R e m a n e, J. 1986. Calpionellids and the Jurassic-Cretaceous boundary. - Acta Geo/. Hungarica, 29 (1-2); 15-26. Reman e, J. , B aka I ova -I van ova, D., B o r z a, K ., Knauer, J., Nagy, I, Pop, G., Tare d i - F i I a c z, E. 1986. Agreement on the subdivision of the standard calpionellid zones defined at the II Planktonic Conference, Roma 1970. - Acta Geol. Hungarica, 29 (1-2); 5-14. Sap uno v, I. G. 1976. Ammonite Stratigraphy of the Upper Jurassic in Bulgaria. I. Rock and ammonite successions. - Geol. Balcanica, 6, 3, 17-42. T r e j o, M. 1980. Distribucion estratigrafica de los Tintinidos mesozoicos mexicanos.- Rev. In st. mex. Petroleo, 12, 4-13 . Zeiss, A. 1986. Comments on a tentative correlation chart for the most important marine provinces at the Jurassic-Cretaceous boundary.- Acta Geo/. Hungarica, 29 (1-2), 27-30. E aKa JI o B a, LJ:. 1977. KamrnoHeJIHAH OT l.(eHTpaJIHHll H 3anaAHHll fipeA6aJIKaH.- IIaAeoHmoA., cmpamuzp. u .11/111011., 6; 65-80. H H K 0 JI 0 B, T. r., C a n y H 0 B, l.f. f'. 1970. 0 perHOHaJibHOK CTpaTHrpa 23 PLATE I All figures x 400 1. Chitinoidella insueta R e han e k. Chitihoidella Zone, Ch. dobeni Subzone, Komshtica section, sample 0205 2. Chitinoidel/a slovenica B o r z a. Chitinoidel/a Zone, Ch. dobeni Subzone, Komshtica section, sample 0204 3. Chitinoidella tithonica B o r z a. Chitinoidella Zone, Ch. dobeni Subzone, Komshtica section, sample 0204 4. Chitinoidella dobeni B o r z a (a} and Chitinoidella tithonica B o r z a (b). Chitinoidella Zone, Ch. dobeni Subzone, Komshtica section, sample 0203 5,6. Chitinoidella dobeni B o r z a. Chitinoidel/a Zone, Ch. dobeni Subzone; 5 - Komshtica section, sample 0203, 6 - Barlja section, sample 0310 7,8. Cltitinoidella boneti D o be n. Chitinoidel/a Zone, Ch. boneti Subzone, Komshtica section, sample 203 9. Praetintinnopsella andrusovi B o r z a. Praetintinnopsel/a Zone, Komshtica section, sample 205 10. Tintinnopsella remanei B o r z a. Crassicollaria Zone, T. remanei Subzone, Komshtica section, sample 207 11,12. Tintinnopsella carpathica (M u r g e an u & F i I i pes c u). 11 - Crassicollaria Zone, Cr. massuti niana Subzone, Barlja section, 306, 12 - Calpionella Zone. C. alpina Subzone, Barlja section, sample 222 13, 14. Crassicollaria intermedia (D u ran d De I g a). Crassicollaria Zone, Cr. massutiniana Subzone; 13 - Komshtica section, sample 214, 14 - Barlja section, sample 305 15,16. Crassico/laria massutiniana (Co I om). Crassicol/aria Zone, Cr. massutiniana Subzone; 15 - Barlja section, sample 305, 16 - Komshtica section, sample 217 PLATE II All figures x 400 1.2. Crassicollaria brevis Reman e. Crassicollaria Zone, Cr. massutiniana Subzone, Barlja section; 1 - sample 307, 2 - sample 309 3,4. Ca1pionella alpina L o r e n z (large form). Crassicol/aria Zone, Cr. massutiniana Subzone, Barlja section• 3 - sample 307, 4 - sample 309 5,6. Calpionella alpina L o r en z (medium-sized form). Calpionella Zone, C. alpina Subzone, Barlja section; 5 - sample 314, 6 - sample 322 7,8. Homeomorph 'Calpionella elliptica C a d i s c h. Crassicollaria Zone, Cr. massllliniana Subzone, Barlja section, sample 310 9. Crassicollaria parvula R e m a n e. Crassicollaria Zone, Cr. mas: utiniana Subzone, Barlja section, sample 310 10,1J. Crassicol/aria colomi Do ben. Calpionella Zone, C. alpina Subzone; 10- Barlj~ section, sample 313, ll - Komshtica section, sample 222 12. Remaniella cadischiana (Co I om). Ca1pione/la Zone, Remaniella Subzone, Barlja section, sample 323 13, 14. - Calpionella elliptica C a d i s c )l. Calpionella Zone, C. elliprica Subzone; 13- Barlja section, sam ple 328, 14 - Komshtica section, sample 243 15. Tintinnopsella carpathica (M urge an u & F iIi pes c u) - T. tonga (Co I om). Calpionella Zone, C. el/iptica Subzone, Barlja section, sample 328 16. Calpionellopsis simplex (Co I o m). Calpionellopsis Zone, C. simplex Subzone, Komshtica secticn, sarr.ple 246 24 PLATE I 1 2 3 4 6 7 10 11 12 13 15 16 I. La k o v a - Middle Tithonian to Berriasian. CEOLOGICA BALCANICA, 23 . 6 PLATE II 6 13