GEOLOGICA BALCANICA, 30. 1-2, Sofia, Jun. 2000, p. 59-67
New data on the Middle and Upper Jurassic stratigraphy in the Konyava Mountain, SW Bulgaria
1 1 1 Ivan Zagorchev , Ekaterina Trifonova , Daria lvanova , 1 2 2 Kristalina Stoykova , Emil Goranov , Petko Pemov
1Geologicallnstitute, Bulgarian Academy of Sciences, 1113 Sofia; E-mail za&or@&eoloc bas b& 1"Sojgeoproouchvane" Ltd. (Submitted: June 23, 2000; accepted for publication: June 23, 2000)
3ai!op'leB, He .. TpurftoHOBa , E .. HeaHoea, ~. . CmouKOBa, Abstract. A transition from the classical Jurassic Balkanide Kp .. ropaHOB, E .. fleMOB, n. HOBble c>aHHble 0 cpec>He- u development towards the predominantly terrigenous eepxHeiOpCKOU cmpamui!parftuu i!Opbl KoHRBbl, 103 EoAi!a sedimentation pattern of the Treklyano zone is observed in the pUR. B npe.11enax ropbl KOHliBbl OC)'llleCTBJJlleTCll nepexo.ll OT Konyava Mountain. Most of the sections begin with the JUlaccH'fecKoro IOpcKoro pa3peJa lianKaHH.Il K npeKM)'llleCT sandstones of the Gradets Formation (Toarcian - Aalenian aeKHO TepHreHHOMY pa:1pe3y TpeiUlliHCKOH JOHbl. lioJJbWHH Stage) followed by the Polaten Formation (shallow marine CTBO pa3pe30B Ha'fHHaiOTCll neC'faHHKaMH fpa.lleUKOH CBHTbl limestones; Aalenian - middle parts of the Bathonian Stage), (ryapCKHH - aaneHCKHH llpycb), CJJeD,)'IOT 00JJaTeHCK3ll CBH Momchil Formation (shales and marls with limestone Ta (MeJJKOBO.IlHble MOpCKHe HJBeCTHliKH; aaneHCKHH- cpe.ll interbeds; upper parts of the Bathonian Stage - Oxfordian HHe 'faCTH 6aTcKoro llpyca), MoM'fHJJCKall CBHTa (aprHJJJJHTbl Stage), and the flysch Kostel Formation (Upper Jurassic). H MeprenH nepecJJaHBaiOlllHeCll nec'faHHK8MH; BepXHHe 'faCTH Some parts of the Kostel Formation are characterized here by 6aTcKoro llpyca -oKc
Zagorchev, 1., Trifonova, E., Ivanova, D., Stoykova, K.., Goranov, E., Pemov, P. 2000. New data on the Middle and Upper Jurassic stratigraphy in the Konyava Mountain, SW Bulgaria- Geologica Bale., 30, 1-2; 59-67. Key words: Middle and Upper Jurassic; lateral variations; SW Bulgaria
Introduction ping or extensive revisions bring forth new evidence that throws new light on palaeogeodynamic issues. The Jurassic stratigraphy, palaeogeography and The new geological mapping on the scale pa1aeogeodynamics of Bulgaria has marked con 1:25000 by Sofgeoproouchvane Ltd. in 1997-1999 siderable achievements and progress (s. Sapunov, gave opportunities for new revisions. Partially Tchoumatchenco, 1994). In Southwest Bulgaria, im published (Zagorchev et al., 1998) data about new portant evidence and conclusions (Ha'leB, 1969, Jurassic formations are here enlarged with new 1973, 1985) have found partial confmnation and biostratigraphic data on the Jurassic pre-flysch considerable improvement by ,[{o,aeKOBa et al. (1984), and flysch of the Nish-Troyan trough. The authors CanyHoB et al. (1983, 1985) and 3arop'leB, are grateful to Sofgeoproouchvane Ltd. for logistic THXOMHpooa (1986). However, the geology of the and financial support, and to Prof. I. Sapunov, for Krayshte region is so complex that every new map- field and laboratory consultations.
59 The present paper is a contribution to the (see Fig. 1). and namely (from west to east, and project 603 "Stratigraphic and tectonic correlations from bottom to top): of SW Bulgaria with the adjacent countries" of the (1) Treklyano sedimentation zone, western part: National Fund "Scientific Research". Metohiya Formation (lower Middle Jurassic) - Sredorek Formation (Middle- Upper Jurassic) Kostel Formation (Tithonian - Berriasian) The Middle - Upper Jurassic Treklyano sedimentation zone, central part: basin in Southwest Bulgaria Dobridol Formation (Toarcian? - Aalenian) - Rayantsi Formation (Aalenian? - Oxfordian - The Jurassic evolution of SW Bulgaria has first Kimmeridgian?) - Kostel Formation (Tithonian been thoroughly studied by Nachev (1970, 1974; Berriasian) Ha'feB, 1969, 1973, 1985). In his interpretation, the Treklyano sedimentation zone, eastern part: Po sedimentation proceeded in the consequent for laten Formation (Aalenian?- Bathonian) - Mom mation of the following geocomplexes: 1) conti chi! Formation (Bathonian? - Callovian - Kim nental terrigenous (Hettangian); 2) marine trans meridgian?)- Kostel Formation (Tithonian - Ber gressive terrigenous-carbonate (Upper Hettangian riasian) to Aalenian); 3) terrigenous (Aalenian - Bajo (2) Svetlya sedimentation zone (Jurassic gra cian); 4) terrigenous-carbonate (Bajocian- Batho ben): continental Zhablyano Formation (Lower nian); hiatus; 5) carbonate; 6) flysch (beginning Pliensbachian) - Ozirovo Formation (Upper with a preflysch in Kimmeridgian - Lower Titho Pliensbachian) - Gradets Formation (Toarcian - nian, continuing with a flysch in Tithonian to Ear Lower Aalenian?) - Polaten Formation (Aalenian ly Berriasian, and ending with carbonate post - Bathonian), hardground and hiatus - Lobosh flysch in Middle - Late Berriasian). The sedimen Formation (Callovian - Oxfordian) - Neshkovtsi tological features of the flysch have been also thor Formation (Kimmeridgian) - Kostel Formation oughly studied (e.g .• Nachev, 1970, 1974; Dimitr (Tithonian- Berriasian) ijevic, Dimitrijevic, eds .• 1987). Locally, the Juras (3) "Classical" Balkanide sedimentation with sic sedimentation has begun directly with a trans Upper Jurassic flysch: Gradets Formation (Toar gression of the terrigenous-carbonate (Bajocian - cian - Lower Aalenian) - Polaten Formation Bathonian) geocomplex. Several internal Jurassic (Aalenian- Bathonian), hardground, hiatus - Ya discontinuities have been referred to tectonic in vorets Formation (Callovian) - Gintsi Formation tra-Jurassic phases. (Oxfordian- Kimmeridgian)- Neshkovtsi Forma Although corresponding to the real evolution tion (Kimmeridgian) - Kostel Formation (Titho (with some age corrections) in large parts of the nian- Berriasian) Jurassic basin, this very generalized idea had to be (4) Sedimentation with Upper Jurassic carbon changed by later studies (CanyHoB H .ap., 1983, ate platform (e.g., Lyubash unit): Polaten Forma 1985; .l{o,aeKOBa H ,ap., 1984; JarOplfeB, THXOMH tion (Aalenian- Bathonian)- Yavorets Forma pooa, 1986; Zagorchev, 1986; 3aropqea, .l{HHKOBa, tion (Callovian) - Gintsi Formation (Oxfordian - 1991; 3arop'feo, 1993; Zagorchev et at., 1998). Sed Kimmeridgian) - Slivnitsa Formation (Kimmerid imentation areas with substantially different devel gian -Hauterivian) opment have been outlined on the basis of detailed Remark. In view of the diachronous boundaries lithostratigraphy completed with new biostrati of the lithostratigraphic units, their range quoted graphic evidence, including new fossil groups for above is only indicative one. the region: brachiopods, miospores, foraminifers, Konyava Mountain (Fig. 2) is the border area radiolarians, calcareous nannofossils. One of the between three principal sedimentation zones. crucial problems concerns the transition from the Based on several important fossil findings, it has gradually deepening Middle - Late Jurassic basin been regarded as an area of the "classical" Bal to the flysch sedimentation of the Nish-Troyan kanide sequence. Field and laboratory studies trough. Several type sections have been outlined pointed at the broad occurrence of the Momchil
Fig. I . Comparative columnar sections for the Jurassic in the Konyava Mountain and some adjacent areas. Abbreviations for the names of the formations: dd - Dobridol Formation; g - Gintsi Formation; gr - Gradets Formation; zh - Zhablyano Forma tion; j - Yavorets Formation; lcs - Kostel Formation; lo - Lobosh Formation; mm - Momchil Formation; mt - Metohiya Formation; n - Neshlcovtsi Formation; po - Polaten Formation; ra - Rayantsi Formation; sl - Slivnitsa Formation; sr - Sre dorek Formation cliKr. I. CpaaHKTenHK JConoHJCOBK pa3pC3K Ja 10pan a KoHna nnaHKHa K HROK CDce.llHK o6n'llcTK. CaKpatUeHKll 3a KMeHaTa Ha CBKTKTe: dd - Jlo6piUlOnCICa; 8 - rKHCJCa; gr - rpueun; zh - >Ka6niHCJCa; j - jfaopeun; ks - KocrencJCa; lo - Jlo6owu; mm - MOM'fKncJCa; mt - MeToxKiicxa; n - Hewxoacn; po - nonaTeHcxa; ra - PuHcJCa; sl - CnKBHKWJCa; sr - Cpe.llopeJCcxa
60 Strouma superunit Lyubash time, Sredorek Rayantsi Rayantsi Klapar Tsurv Lobosb - unit Ma West East ovtsi enyano Chepino
lu.cretaceous Turonian I- 100
Albian
I- 110
Ill Aptian =Q ~ u 1- 120 ~• Hauterivian u
BUTemlan r- 130
Beniaslan :::----:::: ks :-::: ks ••-:: ~:~::::.::.-:::.::. f..::: -••--- • ••••••--- ••••- •••••••••••.•• ------:.:.- k; ::::.- ::.-~ ks • :~: •••••••••••••• .!::.:.:::··.: ::;· .:::.: ks .:::.: :·;:____ :·.:: ~!.!..:'..:!~~!.!: 1------4 ? ? ::.::.:::.:.::.:.::. ::::. .••••::::·. n ·:.... :.. .. :.: n :.:·:.:·:.:·· Kbnmerldg. ? ::::::::::::::-. ::-;:-:::-.-:::-.-:: hiatus ? I I I _l ? : g~ --....·-- ...... ·- - .... .----...... ·----.....·-- . Oxfordian -- J ~ ? 160 ~Imm-:.-:. u CaDovtan ra -;; ;;-.:.:::::•;- I& hiatus hiatus hiatus c: Bathonian · ~ · - sr mm ~-= po po po 170 Bajocian - ...... Aalenian ...... ~~~~0~ O:.{dd_l~:c;: - 180 ~gr~····~····..... Toardan ..······...... ·········...... - 190 PUensbach. ~oz~ O~·~lll_Zb
Stnemurlan r- 200 Hettangian
Rhaetian ~kbT3~ u r- 210 -;; ::panT3 ~ ::i kmTJ E:: I& Gl Norlan -- -- :- ~~l~~~~~~ 1: E-1 l_ _l _[ 1-L trT trT3~ P=*1 3J:r cqtrT3~ f-. 220 _]f -11 ~trT~tc =.t trT t c:::r:::::l ~_I I 1 3 r2~
61 Kostel Formation (Upper Jurassic) Momcbll Formation (Middle -Upper Jurassic) Y avorets, Gintsi & Nesbkovtsi Formations (Callovian - Kimmeridgian) Polaten +/- Gradets Form ations (Middle Jurassic) pre-Jurassic basement 20 ~ ---- Khp~~/'------1 ~------~~ ------__, ~------40~------~
0
Fig. 2. Simplified map for the distribution of the Jurassic formations in the Konyava Mountain, and the position of the principal sections studied c!>Kr. 2. OnpocTeHa KapTa Ja paJnpocTPaHeHKeTO Ha K>pCKKTe CBKTH BKoHIBa nnaHKHa K nonoJKeHKeTO Ha KJy'leHKTe pa3pe3K
Formation in the whole western and southern rims lenticular bodies (very similar to these of the Lo of exposure of the flysch sediments from Zemen bosh Formation) of breccia and breccia-conglo and Blateshnitsa (in the north) to Gorna Koznitsa, merate built up of pebbles from Triassic and Ju with the exception of the outcrops in the locality rassic limestones KJisourata at the village of Tsurvenyano. The best sample 2586 (near KJaparovtsi) - bed of marls exposed section is situated along the road from the and calcareous marls about 1.5 m thick; fragment hamlet of KJaparovtsi towards the peak Viden, and of ammonite, aptychus; Colomisphaera fibrata it has been extensively studied for foraminifers, (Nagy), Colomisphaera carpathica (Borza), Globo calcareous nannofossils, Algae and other micro chaete alpina Lombard, Saccocoma sp. Agassiz - fossils. Another similar section is situated north of Upper Jurassic Series the village of Gorna Koznitsa. Single samples have sample 2587 (in the northern bank of the big been collected SW of the village of Blateshnitsa. brook valley) - about 2 m of marls and marly limestone; Lombardia arachnoidea Bronnimann - Upper Jurassic (Kimmeridgian?) Description of the sections sample 2588 (middle parts of the section) - siltstones with occasional thin limestone beds Section KJaparovtsi lower parts of the section of the Kostel Formation: (in the road cut on the road from KJaparovtsi to sample 2621 (at the turn of the road, about 40 m the peak Viden) above the top of the Polaten Formation) - about 2 cove~ Palaeogene (not exposed along the m of sandy biodetrital limestone rich of various section) fragments from algae and megafossils; microfo Kostel Formation (Bobovo Member?) (Upper ssils determined: Nubecularia sp., Verneuillina sp., Oxfordian? Substage - Tithonian Stage) - about Pseudocyclammina lituus Yokoyama, Tubiphytes 400 m (s. also CanyHoB et aL, 1985): alternation of morronensis Crescenti, Paalzovella feifeli elevata sandstones, polymictic conglomerates and bre (Paalzow)- Upper Jurassic • ccia-conglomerates, marls to calcareous marls; sample 2589 (25 m above the top of the PoIaten
62 Formation) - sandy limestone (4) 8 em marl; sample 2580: Discorbis scutilifor sample KLll - marl, about 10m above the base mis E. & I. Seibold, Ophthalmidium ex gr. carina the limestone bed of sample 2590: Watznaueria tum Kubler & Zwingli, Vemeuilinoides mauritii nnT"PID«ae (Black) Perch-Nielsen, w. biporta Buk (Terquem),Eoguttulina liassica (Strickland), Eogu Cyclagelosphaera margerelii Noel (Upper ttulina sp., Haplophragmoides sp., Reophax sp., Jurassic) crinoids; Middle Jurassic sample KLIO - marl, about 8 m above sample (3) 2.2 m marl KL7: Ellipsagellosphaera britannica (Stradner) sample KL3 in the upper part: Colomisphaera Perch-Nielsen, E. fossacincta Black (Upper Ju fibrata (Nagy), Colomisphaera carpathica (Borza), rassic) abundant calcareous nannofossils Watznaueria sample KL9 - marl, 6.5 m above sample KL7: biporta Bukry, Cyclagelosphaera margerelii Noel, Nannoconus compressus Bralower & Thierstein - Cyclagellosphaera dejlandrei (Manivit), Ellipsage- Middle Tithonian (!); Parhabdolithus embergeri 1/osphaera britannica (Stradner) Perch-Nielsen: (Noel) Perch-Nielsen (first occurrence in Late Middle Jurassic Kimmeridgian); Cyclagelosphaera margerellii (2) 8 - 10 em limestone; sample KL2: E/lipsage- (Noel) 1/osphaera sp. indet.; Ophthalmidium strumosum sample KL8 - marl, 2 m above the base of the (Guembel), Ammobaculites sp., Nubecularia sp., marl interval, and 3.8 m above sample KL7: Dobrogelina sp. - Middle Jurassic Colomisphaera jibrata (Nagy~ Colomisphaera (I) I m marl and shale carpathica (Borza) - Upper Jurassic; strongly Polaten Formation (parts of the Aalenian Stage recrystallized Watznaueria biporta Bukry and W. - Middle Bathonian Substage) - about 15-18 m barnesae (Black) Perch-Nielsen; Ellipsagellospha in the uppermost part - 20 em aphanitic lime era britannica (Stradner) Perch-Nielsen, stone, slightly nodular; sample KLI: Globuligerina sample 2590 (about I 0 m above the top of the oxjordiana (Grigelis), Lenticulina sp., Nodosaria Polaten Formation) - sandy limestone to calca sp., Globochaete alpina Lombard, Saccocoma sp. reous sandstone, about 1.8 m thick; sample KL7 Agassiz; Middle Jurassic about 30 em above the base of the bed: Watzna gray limestone, biodetritic limestone, oolithic ueria barnesae (Black) Perch-Nielsen; Pseudo limestone, calcareous sandstone cyclammina lituus Yokoyama, Everticyclammina sample 2579 (gray biodetritic limestone from the sp., Koskinobullina socialis Cherchi & Schroeder, uppermost part of the Polaten Formation): Opht Tubiphytes morronensis Crescenti - Upper Jura halmidium ex gr. carinatum Kubler & Zwingli ssic; this assemblage is indicative of a very shallow Gradets Formation (upper part of the Toarcian sedimentation environment Stage?- parts of the Aalenian Stage)- about 8 - 15 lithological transition from the Momchil For m: calcareous sandstones, locally with single qu mation: artz and quartzite pebbles (9) 2,4 m shale and marl with thin (3 - 4 em) transgressive unconformable boundary over wa sandstone beds; sample KL6: Ellipsagellosphaera shed-out irregular surface fossacincta Black (Upper Jurassic) basement: Komshtitsa Formation (Upper Car (8) 2-5 em interbed of sandy limestone; sample nian - Norian): red shale and marl interbedded KL5 with quartz oligomictic sandstone (7)1 m marl; sample KIA: Watznaueria biporta Bukry, abundant big specimens of Cyclagellospha Section Gorna Koznitsa era dejlandrei (Manivit), Ellipsagellosphaera bri tannica (Stradner) Perch-Nielsen; Ophthalmidium (the section is situated along the local road North strumosum (Guembel), Colomisphaera carpathica of the village; data by CanyHOB et al., 1985 have (Borza) - Upper Jurassic been also incorporated in the description) Momchil Formation (Bathonian? Stage or lower cover: conglomerates and sandstones (Palaeo part of the Callovian Stage - Oxfordian Stage) - gene) about 7 m shales and marls with interbeds of sandy depositional unconformity li mestone and calcareous sandstone, with Kostel Formation (Bobovo Member?) (Upper abundant fossil debris, ooids and foraminifers Kimmeridgian Substage - Lower Tithonian Sub (6) 17 em sandy limestone; sample 2581: Discor stage) - more than 200 m bis cf. paraspis Schwager, Trocholina cf. palastin The section begins with packet 3 of CanyHoB et ensis Henson, Archaeosepta platierensis Wernli, al. ( 1985) (here packet 12) Bolivina cf. liassica (Terquem), Ophthalmidium ex (12) 6.5 m sandstone to fine-pebble conglo gr. carinatum Kubler & Zwingli, Ophthalmidium merate with calcareous cement sp., Algae, crinoids, bryozoans etc. - Middle Juras (11) 4 - 5 m medium-pebble (but with occasional sic (Bathonian? -Callovian Stage) pebbles up to 0.5 - 1.5 m) conglomerate to breccia (5) 12 em marl conglomerate built up of pebbles from limestone
63 and marl, silicitic and siderite concretions, san the formation as parts of the Middle Jurassic Se dstone, phyllite and quartz; some of the pebbles ries (Bathonian? -Callovian) and possibly, parts from Jurassic limestones contain corals and am of the Upper Jurassic Series (Oxfordian). In con monites; in one such pebble, the Late Oxfordian siderable parts of the Konyava Mountain (from Perisphinctes (Dichotomoceras) crassus Enay has Gorna Koznitsa to Blateshnitsa), both the compo been determined. sition of the formation and its position (fast litho sample 2609 logical transition from the Polaten Formation, and (10) 2m limestone transition to the flysch sediments of the Kostel sample 2615 - limestone from the base of the bed Formation), and its age correspond to the type sec (9) 10 - 12 m alternation of thin-bedded marl, tion. The thickness varies here between I 0 and 40 sandstone and limestone, with irregular bedding m, too. Limestones from the lower parts of the and convolutions Momchil Formation contain the typical Middle (8/ about 3 - 5 m massive limestone Jurassic (Aalenian to Bathonian, possibly also up sample 2614- limestone to Callovian) foraminifers Ophthalmidium carina (7) 5 - 6 m marls with sandstone interbeds tum (Kubler & Zwingli), Discorbis cf. paraspis sample 2613 - marl: Cyclagelosphaera margerelii Schwager, Archaeosepta platierensis Wernli, Boliv Noel, Watznauereia barnesae (Black) Perch ina cf. liassica (ferquem), Ophthalmidium sp., Nielsen (Upper Jurassic) Discorbis scutiliformis (E. & I. Seibold), Trocholi (6) 2 - 3 m limestone conglomerate with na palastinensis Henson, Lenticulina quenstedti interbeds of marly limestone (Gumbel),Bolivina liassica (Terquem),Protopener sample 2612 oplis striata Weinschenk, Verneuilinoides mauritii (5) 10 - 12m (without good outcrops) sandstone (ferquem), Eoguttulina liassica (Strickland), and limestone Eoguttulina sp., Haplaphragmoides sp., Reophax (4) about 0.5 m limestone sp., that are present also in the underlying Polaten sample 2611: Everticyclammina sp., Koskino Formation. The marls yielded the calcareous nan bullina socialis Cherchi & Schroeder, Tubiphytes nofossils Watznaueria barnesae, Ellipsagello moronensis Crescenti - Upper Jurassic (Kimme sphaera brittanica, Cyclagellosphaera margereli, ridgian? Stage) etc. In the upper parts the fossils Ophthalmidium (3) 8 m sandstone, marl and siltstone in inter strumosum (Guembel), Colomisphaera carpathica bedding (Borza), indicate a Late Jurassic age (parts of the Momchil Formation (Middle- Upper Jurassic) Oxfordian Stage). (2) 4.5 m dominant gray and greenish fine-bed The upper formation boundary with the flysch ded silty marls interbedded with calcareous lime Kastel Formation is set on at the occurrence and stone gradual dominance of turbidite beds. Thus, the Polaten Formation (Aalenian - Bathonian) boundary has a transitional character, and is ( 1) biodetritic, oolithic and sandy limestones lo situated somewhere within the Oxfordian Stage. cally interbedded with calcareous sandstones with Probably the Momchil Formation has lateral remains of belemnites and brachiopodes interfingering boundaries with the Yavorets and sample 2610 Gintsi Formation of the Balkanide Jurassic as well basement: dark-gray to blackish nodular lime as with the Lobosh Formation from the Svetlya stones of the Radomir Formation (Ladinian Stage Jurassic graben. A lateral transition towards the of the Middle Triassic) deeper facies of the Neshkovtsi Formation is also deduced. However, although the background of Momchil Formation both formations consists of marls, the presence of in the Konyava Mountain limestone beds with typical shallow-marine fossils in the Momchil Formation shows that this Momchil Formation has been introduced (Zagor formation is bound to a shallower environment chev et al., 1998) for an alternation of shales, marls possibly closely related to a palaeo-delta. and siltstones with a few thin beds of sandy lime stones and calcareous sandstones. The limestones Kostel Formation contain abundant fossil debris and ooids, and are in the Konyava Mountain lithologically very similar to the limestones of the Polaten Formation. The Momchil Formation cov The Kostel Formation is widespread in the ers usually with a fast lithological transition the Konyava Mountain (CanyHoB H ,np., 1985). It is Polaten Formation (e.g. in the Zemen borehole - characterized by a coarse flysch, with rhythmic 3arop'ieB et al., 1990), or covers directly with an interbedding of thick packets of thick-bedded unconformable contact Upper Triassic rocks coarse- to fine-grained sandstone, shaly siltstone (Trun or Komshtitsa Formation). The foraminifers and shale, and packets of limestone breccia and calcareous nannofossils indicate the range of conglomerate, polymictic conglomerate and marls
64 with limestone intervals. It has a gradual tran lituus Yokoyama, Tubiphytes morronensis sitional contact above the Momchil Formation, Crescenti, Paalzovella feifeli elevata (Paalzow), that is marked with the dominance of turbiditic Lombardia arachnoidea Bronnimann, beds. Some of the lenses and layers of breccia and Everticyclammina ~ Koskinobullina socialis conglomerate have an olistostrome character, and Cherchi & Schroeder. The Kastel Formation most are very similar in some sections (Gorna Koznitsa) probably should be referred in the Konyava to the breccia-conglomerate of the Lobosh For Mountain to uppermost parts of the Oxfordian mation. Within the beds referred to the Oxfordian? Stage (or lowermost parts of the Kimmeridgian or lowermost parts of the Kimmeridgian Stage the Stage) - parts of the Tithonian Stage. The na following fossils have been determined: Colo nnofossil species Nannoconus compressus Bralo misphaera fibrata (Nagy), Colomisphaera carpa wer & Thierstein in the middle parts of the section thica (Borza), Globochaete alpina Lombard, Sacco Klaparovtsi is regarded as indicative of the Titho coma sp. Agassiz. The beds referred to the Kim nian Stage. The presence of fossils as Tubiphytes meridgian and Tithonian Stage contain Nube morronensis indicates, at least for a part of the cularia sp., Verneuillina sp., Pseudocyclammina formation in the Konyava Mountain, again a
( . I
. ~
:- ......
I ·' i I / 0 2 4 6 8 10 12 km Central Balkan "'-e Flysch Group b• Oj CBFG over CBFG over (CBFG) over I o o Lobosh Formation Treklyano Group Gintsi Formation
Fig. 3. Sketch map for the distribution of the different Jurassic section types in a part of SW Bulgaria; arrows- palaeocurrent directions (after Nachev) in nysch Hr. 3. CxeMaTH'fHa Kapra Ja pa3npocrpaHeHHero Ha paJJJH'fHHTe IOpCJCH THnoeH pa3peJH a 'fSCT or 103 lil>nrapH.A; nocoKa Ha naneorpaHcnopra 81>8
9 Geologica Balcanica, 1-2/2000 65 shallower environment possibly linked to a near new palaeogeodynamic analysis for the evolution palaeo-delta. of the Jurassic basins, and especially of the Nish Troyan flysch trough, would be facilitated by the new evidence published here but will need addi Conclusions tional studies as provenance analysis and more detailed biostratigraphy. Most of the Jurassic sections and outcrops in the Konyava Mountain display a continuous sequence that consists of the Gradets Formation (Toarcian References - Aalenian), Polaten Formation (Aalenian - Bathonian), Momchil Formation (Bathonian? - Dimitrijevic, M .N ., Dimitrijevic, M .D . (eds.) 1987. The lurbi Callovian - Oxfordian) and Kostel Formation ditic basins of Serbia. Serb. Acad. Sci. Arts, Monograph (Oxfordian? - Kimmeridgian - Tithonian - 576, Dept. nat. math. Sci., 61, Belgrade. Berriasian?). The age of the Momchil and Kostel Nachev,l. 1970. Palaeogeography of the Krayshtc Region (SW Formation is determined on the basis of several Bulgaria) in the Tithonian. - Cnuc. 5blli!. i!eOA. o-60, 31, I ; microfossil groups. It should be noted that the ages 51 -62. N achev, I. 1974. The Tithonian nysch in Bulgaria. - H 36. determined after foraminifers, algae and calca reo11. uncm.. cep. Cmpamtup. u AumoA .. 23; 191 -204. reous nannofossils exhibit some discrepancies. Sapunov, 1., Tchoumatchenco, P. 1994. Introduction a Thus, the age of the Momchil Formation deter !'evolution tectonique et paleogeographique de Ia Bulgarie mined by foraminifers is mostly focused on the au cours du Jurassique. - Geobios, MS 17; 723-732. Zagorchev, I. 1986. Jurassic palaeogeography of a part of Middle Jurassic (Bathonian? - Callovian) with South· West Bulgaria in the light of new stratigraphic data. - continuation in the lower parts of the Oxfordian Geologica Bale., 16, 5; 3-20. Stage. Algae and cadosinids in the same formation Zagorchev, 1., Trifonova, E., Budurov, K.., Stoykova, K. 1998. are usually considered as Callovian to Upper Newly recognized Upper Triassic and Jurassic formations Jurassic (mostly Oxfordian). The first appearance in Southwest Bulgaria: palaeogeographic and palaeogeody cf Nannoconus in sample KL9 of section Kla namic implications. - Geologica Balcanica. 28, 1-2; 35-43. .[lHMHTp08, U . 1931 . flpHHOC XDM reonOfHliTa H ne-rporpa 66 noJKeHHH JOro·3ana.nHoH IionrapHH. ·Geologica Bale., 15, MoM'IHJICKa CBHTa - KocTencKa CBHTa (Eo6ooc 2; 3·62. KH 'IJieH). Y CTaHOBJIB3T ce JiaTepaJIHH npeXO.llH TeH'IOB, R. (pe.n.) l993.Pe'IHUK Ha 6uzapcKume o¢uquaAHU Me)l(.llY TOJH pa3pe3 H HJBeCTHHTe OT npe.UHWHH Aumocmpamuzpa¢cKu eduHuqu ( 1882-1992). C., MJ.n. HJCJie.UBaHH.!I llOCJie.UOBaTeJIHOCTH rpa.neuKa CBH IiAH; 397 c. Ta - TioJiaTeHCKa CBHTa - ~BopeuKa CBHTa - rHHCKa CBHTa - HelllKOBCKa CBHTa - KocTeJICKa HosM ,naHHH Ja cpe,nHo- coHra (,KJiaCH'IeCKH" EanKaHH.lleH paJpeJ) H )l(a6- H ropHOIOpCKaTa CTpaTHrpa«!>HR JIJIHCKa CBHTa - 03HpOBCKa CBHTa - rpa.neuKa CBHTa - lloJiaTeHCKa CBHTa - Jlo6owKa CBHTa - B KoHRBa nJiaHHHa, HewKoBcKa coHra - KocTencKa CBHTa (CoeTJIJIH IOroJana,nHa nbJiraplHI CKH IOpCKH rpa6eH). MOM'IHJICKaTa CBHTa H .llOJI HaTa qacT ua KocTencKaTa CBHTa 6JIXa onpo6oaHH 11. 3aropqeo, E. TpH 67