No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Conodont and foraminiferal successions from the Triasic of Bulgaria
Abstract
The Triassic sediments of Bulgaria refers to two different types: Balkanide and Tethyan. One of them - Balkanide is deposited in situ and occupy the larger part of the territory of the country. It is characterized by ammonites and other megafossils, with predominance of Alpine-Tethyan species. These often rich in dark coloured clayey rocks, Pelsonian-Longobardian in age, comprise typical conodont fauna. During the rest of the Triassic period there were unfavourable environments for conodonts. The foraminifers (U. Smithian-Norian) are represented by various Tethyan benthonic species. The foraminiferal assemblages are characterized by a lower diversity of benthonic species and by the permanent presence and prevalence in some places of the typical Tethyan representatives of Oberhausereliidae and Duostominidae. A biostratigraphic subdivision and correlation of these two types of shallow Triassic in Bulgaria has been made, and conodont and foraminiferal zonal standards have been accepted. -from Authors
... Macro and microfossil associations confidently indicate the Balatonites balatonicus Zone based on ammonoids (Ogg et al. 2020) and the Pilammina densa Zone, based on foraminifers. The forminiferal Zone in the Spomen Dom section corresponds to the Pilammina densa Range-Zone in Bulgaria (e.g., Trifonova 1978;Budurov & Trifonova 1995). Both zones belong to the middle Pelsonian (Middle Anisian). ...
... Pilammina densa was first introduced from the Anisian limestones of the Crmnica area in Montenegro (Pantić 1965), and was subsequently documented in many other areas in the Dinarides of ex-Yugoslavia. Very rich similar foraminiferal associations containing this species were documented from the Middle Triassic of the West Carpathians (e.g., Salaj et al. 1967;Borza 1970;Salaj et al. 1983 with references therein), Bulgaria (e.g., Trifonova 1978;Budurov & Trifonova 1995), and other regions of the Tethys (Rettori 1995 and references therein;Martini et al. 1996). However, and this is important to note, specimen rich monospecific assemblage of Pilammina densa were until now reported only in the Pelsonian of the Inner Belt (i.e., in Kučaj or Getic Zone) of the Carpatho-Balkanides (Urošević 1988, p. 372) in Eastern Serbia. ...
... The establishment of a zonal scheme for this age based on benthic foraminifers was very successfully introduced for the Bulgarian and West Carpathian (Slovakia) territories. A biostratigraphic subdivision of the Anisian in Bulgaria is characterized by the Meandrospira deformata IntervalZone, Pilammina densa Range-Zone and lower part of Turiglomina mesotriasica Interval-Zone (Trifonova 1978;Budurov & Trifonova 1995 with references therein) and by the Meandrospira insolita IntervalRange Zone, Meandrospira deformata Interval Range Zone, Meandrospira dinarica IntervalRange Zone, Pilammina densa Acme Zone and Permodiscus pragsoides Interval-Range Zone (in stratigraphic order) in the West Carpathians (Salaj et al. 1983). The stratigraphical range of Pilammina densa in the framework of the eponymous rangezone in Bulgaria has previously been broadly introduced for the upper half of "Hydaspian" (=Bithynian), Pelsonian and entire Illyrian (Trifonova 1978) with its first acme limited to the Pelsonian ( fig. 2, op. ...
Biostratigraphy and sedimentology of the Pelsonian (Middle Anisian) carbonate Jelovica Fm sequence have been documented in detail in the Spomen Dom section (Jelovica-Visočka Ržana region of the Stara Planina Mts, Eastern Serbia). Abundant ammonoids and foraminifers, together with rare brachiopods, nautiloids, bivalves and crinoids characterize faunal associations of the ammonoid Balatonites balatonicus Zone and the foraminiferal Pilammina densa Zone. This is the first report based on ammonoid and foraminiferal faunas, which allowed initial biostratigraphic subdivision of the Middle Anisian strata from the whole Eastern Serbia region.
... They form a base for zonal schemes useful in chronostratigraphic correlations (Kozur, 1972;Trammer, 1975;Zawidzka, 1975;Kovács and Kozur, 1980;Trifonova, 1994, 1995;Kozur, 1999;Brack et al., 1999). However, no standard conodont zonation exists so far for the Tethys Triassic, and the published schemes differ considerably with each other (see Budurov and Trifonova, 1995;Kozur, 1999). This creates some difficulties in correlation of the Germanic and Tethyan successions. ...
... Determination of detailed stratigraphic ranges of particular taxa was based mostly on the reports by Trammer (1971Trammer ( , 1972Trammer ( , 1975, Zawidzka (1975), Kozur (1968Kozur ( , 1972Kozur ( , 1980Kozur ( , 1999, Kovács and Kozur (1980), Kozur et al. (1994), Vrielynck (1987), , Steuber (1992), Budurov and Trifonova (1995), and Budurov and Petrunova (2000). ...
... Tethyan conodonts and materials from other oceanic domains were extensively reported and described in many contributions cited throughout the text. The most important papers are those by: Mosher (1970), Kozur (1974Kozur ( , 1980, Gedik (1975), Nicora (1977), Sudar (1986), Vrielynck (1987), Steuber (1992), Kozur et al. (1994), Budurov and Trifonova (1995), Kovács et al. (1996), Buryi (1997), Orchard and Tozer (1997), Farabegoli and Perri (1998), Budurov and Petrunova (2000). ...
Middle Triassic conodont assemblages in the semi-closed Peri-Tethyan Germanic Basin comprise endemic forms, which evolved within the basin, and immigrants from the Tethys Ocean. Migration from the Tethys proceeded diachronously through three tectonically predisposed pathways (gates) and was controlled by relative sealevel changes recorded in depositional sequences of the Muschelkalk. In the Early and Middle Anisian predominant were the forms that originated in the Eastern Tethys and in southern basins of the Western Tethys. They migrated through the East Carpathian Gate and Silesian-Moravian Gate. In the late Anisian and early Ladinian forms from the Western Tethyan basins prevailed; their migration pathway led through the Western and East Carpathian Gates. The latter gate was active only at the turn of Illyrian and Fassanian. Episodes of migration of the Tethyan forms and dispersal of conodont fauna throughout the German Basin coincide with the transgressive or highstand phases of a particular depositional sequence (as defined by Szulc, 1999). The most significant proportion of the Tethyan species appears to correlate with the maximum flooding surface of the A3 sequence, (Lower Muschelkalk) later they decrease in diversity. In the Upper Muschelkalk the most numerous Tethyan species correspond to the transgressive phase of the L1 sequence. Above the mfs of the L1 sequence only the Germanic forms remain.
... (Budurov & Trifonova, 1994). When stated that gondolelloides and timorensis are distinct conodont species, Budurov & Sudar (1995) and Budurov & Trifonova (1995) have split the former K. gondolelloides R.-Z. and introduced a new zonation with the K. timorensis R.-Z. at the top of the Spathian, and the K. gondolelloides R.-Z. at the base of the Anisian. One may observe that this new proposed conodont zonation is opposite to that promoted by Kozur (1999Kozur ( , 2003a and Kozur & Bachmann (2005), with the two zones placed in a reversed chronostratigraphic order. ...
... timorensis in the lower Botneheia Formation in the Milne Edwardsfjellet section in central Svalbard (Fig. 3/35), the authors implying an early Anisian age by reference to Kçira, Albania and Deşli Caira, Romania sections. As may be seen, the FO of the occurrences conodont species timoresis have been dated either as late Spathian (e.g., Nogami, 1968;Sweet et al., 1971;Kozur, 1972Kozur, , 1974Kozur, , 1975Kozur & Mostler, 1974;McTavish, 1973McTavish, , 1975Goel, 1977;Collinson & Hasenmueller, 1979;Tian, 1982;Wang & Wang, 1983;Matsuda, 1983Matsuda, , 1985Paull, 1988;Budurov & Sudar, 1995;Budurov & Trifonova, 1995), either as early Anisian (e.g., Sweet, 1970a;Koike, 1973;Budurov, 1976a-b;Nicora, 1977;Kozur, 1980Kozur, a-b, 1989Kozur, a, 1999Kozur, , 2003aGupta & Budurov, 1981;Chhabra, 1981;Gupta, 1983;Sweet, 1988;Mietto et al., 1991;Orchard, 1994aOrchard, , 1995Orchard & Bucher, 1992;Orchard & Tozer, 1997a;Garzanti et al., 1995;Kozur et al., 1995;Krystyn et al., 2004;Wu G-C et al., 2007;Grădinaru et al., 2007;Orchard et al., 2007a-b;Nicoll et al., 2007;Horacek et al., 2009;Gorter et al., 2019;Yao et al., 2011;Yan et al., 2015;Liang et al., 2016;Bai et al., 2017;Li M et al., 2018b;Zhang L et al., 2019a;Muto et al., 2020;Muto, 2021;Sue et al., 2021;Song et al., 2021;Kiliç, 2021;Ha et al., 2021;Chen A-F et al., 2021), or straddling the late Spathian-early Anisian boundary interval (e.g., Kemper et al., 1976;Koike, 1981;Igo & Koike, 1983;Sweet & Bergström, 1986;Lozovsky et al., 1989;Buryi, 1989;Budurov et al., 1989;Nakazawa et al., 1994;Klets, 1995). Also, one may observe that many conodont workers have changed through time their options with regard to the stratigraphic range of the conodont species timorensis. ...
The conodont Chiosella timorensis (Nogami, 1968) has for a long time been considered to be a suitable biotic proxy for the Olenekian-Anisian/Early-Middle Triassic boundary. The recently acquired ammonoid record around that boundary clearly shows that the FAD of this conodont is located well below the boundary, i.e., in the late Spathian. In the present paper, it is underlined that the conodont Chiosella timorensis was promoted as a proxy for the nominated boundary in the early 1980s when the ammonoid record around the boundary was not yet well established. On the other side, until the mid 1990s the taxonomic definition and the lineage of the conodont Chiosella timorensis were not well stated, and even now there are still controversial interpretations of the taxonomic content of this conodont species. The new data achieved from the ammonoid/conodont record around the nominated boundary, especially in the western USA, and also in the Deşli Caira section in Romania, firmly demonstrate that the conodont Chiosella timorensis is a defunct proxy for the Olenekian-Anisian/Early-Middle Triassic boundary. As a consequence, the present data on the ammonoid-documented Olenekian-Anisian/Early-Middle Triassic boundary requires the recalibration of all physical events that have been tied to the FAD of the conodont Chiosella timorensis. The case of the Albanian Kçira-section, for which the chronostratigraphic interpretation of the ammonoid record is proved incorrect, definitely makes the conodont Chiosella timorensis a defunct proxy for the nominated boundary. Also, the case of the two Chinese sections recently proposed as being "exceptional" GSSP candidates for the Early-Middle Triassic boundary, which is based on an inconsistent ammonoid/conodont biochronology, fully strengthens this conclusion. The history of the controversial usage of the conodont species Chiosella timorensis in defining the Olenekian-Anisian boundary justifies a discussion about the usefulness of conodonts in the chronostratigraphic calibration of the standard Triassic timescale. One may conclude that the conodonts are not qualified, and have not a reasonable potential, to be used to define or to redefine the boundaries of chronostratigraphic units in the standard Triassic timescale, which have been basically defined on ammonoid biochronology.
... In this paper we follow the biozonation proposed by Budurov and Trifonova (1995; p. 17) with only one modification. This change concerns the position of the Anisian/Ladinian boundary. ...
... Correlation of ammonoid and conodont zones (modificated from Budurov and Trifonova, 1995), with indication of stratigraphic ranges of sections L'Ametlla (LA) and Riera de Sant Jaume (SJ); numbers on columns indicate sections sample levels. in bed 16 and N. excentrica in bed 18. We, tentatively, correlate beds 14±17 with N. cornuta Zone, they would correspond to the P. trinodosus and A. avisianum ammonoid zones; and we, also, correlate beds 18±19 with N. excentrica Zone ( = `C.' reitzi ammonoid Zone). ...
The facies development of the Spanish Triassic corresponds to the typical three-fold subdivision of the Germanic Facies: Buntsandstein, Muschelkalk and Keuper. Two intervals interpreted as epeiric carbonate platforms: lower Muschelkalk (Anisian) and upper Muschelkalk (Ladinian) are recognized during the Middle Triassic of northeastern Spain. These carbonate intervals are separated by one siliciclastic/evaporitic interval interpreted as sabbkha and saline deposits: middle Muschelkalk facies (Lower Ladinian). In northeastern Spain (Catalonian Coastal Ranges), two Middle Triassic sections comprising lower Muschelkalk facies have yielded the following conodont taxa: Paragondolella bulgarica, P. hanbulogi, P. bifurcata, Neogondolella constricta, N. cornuta, N. excentrica and N. basisymmetrica. The conodont sequence allows recognition of the P. bulgarica and N. constricta zones. These results indicate a middle–upper Pelsonian to upper Illyrian age (middle–upper Anisian), and represent the first conodont-chronostratigraphic approximation for the lower Muschelkalk facies of the western part of the Sephardic Province of the Triassic Tethys Realm.
... The Triassic sediments in the Struma Unit belong to the so-called Balkanide epicontinental facies province, which also appears in the other parts of the Balkan orogen. They contain a predominantly Alpine-Tethyan fauna (Budurov and Trifonova, 1995). ...
In the Kraishte area, straddling the borders of Bulgaria, Serbia and North Macedonia, two major Alpine tectonic units are exposed – Vlasina-Morava and Struma. They exhibit quite differing geological evolution until the late Early Cretaceous compressional phase during which the Vlasina-Morava (Supragetic) was thrust onto the Struma (Getic) unit. The Vlasina-Morava Unit consists of Ediacaran-early Cambrian volcano-sedimentary sequence intruded by Cadomian age granites and covered by early Paleozoic marine sediments. The Struma Unit is built of tectonically imbricated Ediacaran–early Cambrian calc-alkaline magmatic rocks and ophiolites covered by Permian to Early Cretaceous sedimentary sequences. Part of the Ograzhden complex, consisting of high-grade ortho- and para-sequences of Ediacaran to Silurian age, is also considered as belonging to Struma autochthon. Post late Early Cretaceous orogenic extension was related to formation of low-angle normal faults associated with partial cooling and denudation in the area and volcanic-free sedimentation. The following Late Cretaceous to Paleogene compressional phase did not affect significantly the Kraishte area. Since the middle Eocene the area was affected by important crustal scale extension related to the formation of detachment faults and sedimentary basins characterised by continental to marine deposits and accompanied by magmatic activity. The following extensional phases, in the late Oligocene–earliest Miocene and middle Miocene–Quaternary time, were also related to faulting and formation of sets of sedimentary basins. These two phases were separated by a late early to middle Miocene strike-slip to transpressional phase characterised by formation of some minor thrust faults associated with major strike-slip fault zones.
... Neogondolella constricta Mosher et Clark is also widespread in southern Tethys. It was used as a diagnostic species to establish the Pridaella constricta (= Neogondolella constricta) range-zone defined in eastern and southeastern Bulgaria, where the Middle Triassic is developed in deeper-water facies (K. Budurov, E. Trifonova, 1995). The stratigraphic range of this species spans entire IIIyrian and earliest Fassanian. According to H. Kozur et at. (1994), however, the upper range-limit of N. constricta Mosher et Clark does not overstep the IIIyrianlFassanian boundary. N. balcanica Budurov et Stefanov -a very rare species in northern Tethys -is characteristic for the ...
Conodonts have been found in the Muschelkalk intervals in seven deep wells located in the central part of the Polish Middle Triassic basin. Total number of 80 specimens has been ascribed to 18 form-species. The presence of Paragondolellahanbulogi and Neogondolellabalcanica IS reported for the first time III Polish sectIons. Germamca and kockeli Zones of the late early Anisian, Pelsonian and ?earliest Illyrian have been found III the Lower Muschelkalk deposits. The Middle Muschelkalk corresponds to the Illyrian without its latest part, and to ?latest Pelson~an. Presenc~ of the Zones .1, 2 and 4, found in the Upper Muschelkalk, allowed to correlate these deposits with the late Illyrian, Fassanmn and ea:lIest Longobardmn. Analysis of geographical distribution of the investigated species revealed that only cosmopolitan conodonts occur III the Lower Muschelkalk whereas its upper part contains also forms endemic for the German Province.
... P. bulgarica is originally reported from Bulgaria (Budurov and Stefanov, 1975). Since then it has long been used as a guide fossil of the P. bulgarica Zone widely adopted in the pelagic facies of the world that is considered initially to characterize the lower Pelsonian (Budurov, 1975;Budurov and Stefanov, 1975) and latterly to embrace almost the whole the Bithynian and Pelsonian (Budurov and Trifonova, 1995;Kozur, 2003). In Spain and South Alps of Italy, this species is found to range into the lower Illyrian (Pisa et al., 1980;Márquez-Aliaga et al., 2000). ...
Detailed conodont analysis on the Yangjuan-Chupiwa section, Xinmin, Panxian County, Guizhou Province, revealed a conodont sequence including four Anisian conodont zones, viz. Nicoraella germanica Zone, Nc. kockeli Zone, Paragondolella bifurcata Zone and Neogondolella constricta Zone. These zones indicate that the upper Guanling Formation consists of strata from the Bithynian to the Illyrian of the Anisian. Appearance of Neogondolella constricta suggests that the Anisian/Ladinian boundary might be in the overlying Yangliujing Formation. The Panxian Fauna with well-preserved marine reptile and fish fossils is proved to belong to the lower part of the conodont Nc. kockeli Zone in the studied area. Thus, the age of the Panxian Fauna could be the early Pelsonian of the Anisian.
Neogondolella constricta (Mosher and Clark, 1965) from the Prida Formation at Fossil Hill in central Nevada was the first conodont described from Middle Triassic strata in North America. The species has since been widely reported from elsewhere despite uncertainties about its taxonomic scope and that of similar related taxa. Poor definition of these taxa has spawned a diverse nomenclature and inhibited use of the group in biozonation. Starting with a growth series of topotype N . constricta , we reassess allied contemporaneous taxa from North America. In Nevada, 11 conodont taxa are identified: N . constricta , N . aldae Kozur, Krainer, and Mostler, 1994b, N . cornuta Budurov and Stefanov, 1972, N. ex gr. mesotriassica (Kozur and Mostler, 1982), N . postcornuta (Kovács, 1994), N . posterolonga Kozur, Krainer, and Mostler, 1994b, N . quasiconstricta n. sp., N . quasicornuta n. sp., and three subspecies of N . excentrica Budurov and Stefanov, 1972. Successive associations of taxa display symmetry transition in posterior platform configuration. Subdivision of the upper Anisian–lower Ladinian is provided by dominant N . constricta plus relatively uncommon N . quasiconstricta n. sp. and N . excentrica primitiva n. subsp. in the Rotelliformis ammonoid zone. This is followed in the Meeki through the Subasperum zones by dominant N . cornuta , associated N . posterolonga , plus relatively uncommon N . quasicornuta n. sp., and a variety of asymmetric elements: the Meeki Zone includes N . aff. N . cornuta ; the Occidentalis Zone adds N . e . excentrica ; and finally, N . e . sigmoidalis n. subsp. appears in the Subasperum Zone. In British Columbia, the three subspecies of N . excentrica are recognized in, respectively, the Deleeni, Chischa, and Matutinum (and younger) ammonoid zones.
UUID: http://zoobank.org/7d58c8c8-cd68-498f-bb84-5d43de47f779
Two types of Triassic sediments could be distinguished on the territory of Bulgaria: Tethyan and Peri-Tethyan. The Tethyan Triassic is allochthonous in its origin. It forms olistolites or rock fragments in breccia-conglomerates within olistostromes in East Stam Planina as well as thrust sheets in Strandzha Mountain. As a rule the Tethyan Triassic rests upon the autochthonous Peri-Tethyan Triassic - coastal shallow - marine sediments of diverse lithology. We summarized the data about foraminiferal contents and foraminifera sequences from Peri-Tethyan Triassic: Northeast Bulgaria (Dobrogea region), Moesian Platform, Central Forebalkan, Northwest Bulgaria, Southwest Bulgaria and St. Ilija Ridge of Sakar Mts. in Southeast Bulgaria. The analysis of the benthic foraminifers occurrence within the Dienerian ? - lowermost part of Pelsonian interval resulted in recognition of three interval biozones: Meandrospira cheni Interval Biozone, Meandrospira pusilla Interval Biozone and Meandrospira deformata Interval Biozone. The foraminifers of the Tethyan Triassic in East Balkan Mts. have always been of special interest because of the typical Tethyan character of the micro- and macrofossils in this region of Bulgaria. In this region were found foraminifers characterizing Meandrospira pllsilla Zone. Due to the absence of the index species Meandrospira deformata, the Zone of the same name in the Tethyan Triassic cannot be recognized.
The conodonts biostratigraphy from the Upper Member of the Guanling Formation to the basal Yangliujing Formation in Yangjuan-Chupiwa Section was re-analysed and the conodont Neogondolella constricta cornuta, Neogondolella constricta longa, Neogondolella constricta balkanica, Neogondolella alpina alpina, Neogondolella cf. Neogondolella acuta, Paragondolella excelsa, Paragondolella torna?sis were described. Based on the stratigraphical distribution and morphological variations of these conodonts, five conodont zones were re-established and the relevant biostratigraphic comparisons were made. The results reveal that: 1) From the Upper Member of the Guanling Formation to the basal Yangliujing Formation, five conodont zones can be investigated. In ascending stratigraphical order, they are Nicoraella germanica Zone (the bottom undefined), Nicoraella kockeli Zone, Neogondolella bifurcata Zone, Neogondolella constricta Zone, and Neogondolella constricta cornuta Zone (the top undefined); 2) These conodont zones are comparable to the same-named conodont zones of the Upper Longtou Formation at Qingyan Section (platform-margin slope) and of the Guandao wedge at Guandao (2) Section (basin-margin facies) in Guizhou Province, and these conodonts are also present in the ammonoid binodosus Zone, trinodosus Zone, and reitizi Zone in the West Tethys; 3) It further proves that the studied strata can be considered as the Pelsonian-Illyrian substages of the Anisian stage (Middle Triassic), not going into the Ladinian of the Middle Triassic.
Conodontenchronologie und Korrelation der Triassischen Niveaus im Strandza-Gebirge (Siidost-Bulgarien)
- K J Bud U R O V
Bud u r o v, K. J., C at a I o v, G. A. Conodontenchronologie und Korrelation der Triassischen Niveaus im
Strandza-Gebirge (Siidost-Bulgarien).-C. R. Acad. bulg. Sci., 31, 8; 1035-1038.
Late Triassic conodonts stratigraphy
- K Bud U R O V
- M Sud A R
Bud u r o v, K., Sud a r, M., 1990. Late Triassic conodonts stratigraphy. -Cour. Forsch. Inst. Senkenberg., 118;
203-239.
Die Conodonten-und Foraminiferen-Zonen in der Trias des Ostbalkans
- K Bud U R O V
- E On Ova
Bud u r o v, K., T r if on ova, E. 1974. Die Conodonten-und Foraminiferen-Zonen in der Trias des Ostbalkans.
-In: "Stratigraphie der alpin-mediterranen Trias ". Symposium Wien, Mai 1973. -Schriftenreihe Erdwiss.
Komm. Osterr. Akad. Wiss., 2; 57-62.
Correlation of Triassic conodont and foraminiferal zonal standards in Bulgaria
- K B U D U R O V
- E T R I F O N Ova
B u d u r o v, K., T r i f o n ova, E. 1984. Correlation of Triassic conodont and foraminiferal zonal standards in
Bulgaria. -C. R. Acad. Bulg. Sci., 37, 5; 625-627.
Stratigraphy of the Triassic in Strandza -Sakar area, SE Bulgaria: conodont and foraminiferal evidences
- K B U D U R O V
- E T R I F O N O V A
B u d u r o v, K., T r i f o n o v a, E. 1991. Stratigraphy of the Triassic in Strandza -Sakar area, SE Bulgaria:
conodont and foraminiferal evidences. -Rev. Bulg. Geol. Soc., 52, 3; 3-18.