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New evidence on the Upper Barremian-Lower Aptian ammonite succession in the north of the town of Popovo (North-East Bulgaria)
... C.S. Nicolăescu-Plopşor et alii (1956, p. 225) described this flint as being a "bluish-grey colour -more or less darker -coarse granulated, low quality raw material", many of the flakes preserving the "limestone crust, without the slightest trace of rolling". Subsequent archaeological investigations from 1958-1960and 1992(Al. Păunescu et alii 19621964, p. 109;Al. ...
The Southern Carpathians and the Balkan Mountains define a broad physiographic area, placed at the centre of current debates on the emergence of the earliest Upper Palaeolithic and the Aurignacian technocomplex, the migration and dispersal routes of Anatomically Modern Humans in Europe, and the pre-Neolithic and the neolithization of the Balkan area. In this archaeological context and state of research, the Upper Palaeolithic sites from the Lower Danube Valley represent a relevant piece in the jigsaw puzzle of past human land use and mobility patterns. The aim of this article is to investigate the similarity between intraclastic-bioclastic cherts from Giurgiu-Călăraşi area and “Kriva Reka” type of Ludogorie chert from NE Bulgaria, by focusing on their macroscopic and microscopic traits and their geological contexts. The distribution of eluvial and primary deposits of Ludogorie chert types from NE Bulgaria reflects the sedimentary facies belts of the Lower Cretaceous Sea. Also, the alluvial deposits reveal the role played by rivers in the erosion, transport, and redeposition further and further away of the Ludogorie cherts, thus generating an extended area abundant in such materials. The geological distribution of Kriva Reka type similar cherts in Romania was confirmed in alluvial deposits around Giurgiu (Frăteşti Formation, Lower Pleistocene, and Danube’s lower terrace deposits, Upper Pleistocene). The archaeological distribution was confirmed in the Upper Palaeolithic open-air sites from Giurgiu-Malu Roşu, Slobozia-Râpa Bulgarilor, and Nicolae Bălcescu-La Vii. Their use by Boian and Gumelniţa Neolithic communities from southern Romania suggests a long time exploitation of local available cherts.
... By the beginning of the 1980s only the Deshayesites deshayesi Zone had been clearly defined (Dimitrova et al., 1961;Nikolov, 1962Nikolov, , 1969Manolov, 1962;Breskovski and Dimitrova, 1968;Dimitrova et al., 1972). New biostratigraphic data were published subsequently (Nikolov et al., 1983;Stoykova, 1986Stoykova, , 1990Ivanov, 1992Ivanov, , 1995Ivanov and Stoykova, 2001). Recently intensive investigations have been carried out on the Barremian and partially on the Aptian Stage Idakieva, 2008, 2009). ...
Sediments of Early Aptian age in Bulgaria can be assigned to four different facies: platform carbonates (Urgonian complex), shallow-water siliciclastics, hemipelagic and flyschoid siliciclastics. The taxonomic analysis of the ammonite faunas of 18 sections from these four different facies resulted in a revision of the existing ammonite zonation scheme so far applied in Bulgaria and adjoining areas. A new biostratigraphic scheme, which bridges the western and eastern Tethys, is thereby proposed for the Lower Aptian of Bulgaria.
In this synthetic work are reconstructed seven paleogeographic maps corresponding to the main stages of the geodynamic evolution, from Barremian to Albian, along a complex segment of the North-Tethyan margin in Bulgaria. This reconstruction follows the recent publication of three paleogeographic maps related to the Berriasian - Hauterivian interval. The herein proposed facies maps are explained by palinspastic cross-sections, variously oriented, showing the geometric assemblage of the most classic formations used in the Bulgarian literature, constrained by a new biostratigraphy, particularly founded on ammonites, and our recent studies in terms of sequence stratigraphy. Between the emerged (or croded) areas of the Romanian Dobrogea to the north and the Rhodopes/Serbo-Macedonian massif to the south (itself fringing the Tethyan oceanic crust), the Bulgarian Balkanides and Moesia correspond during early/middle Cretaceous times to a wide east-west oriented arm of the sea, filled up during the Hauterivian by the terrigenous series of the "Axial Basin". Just before the Barremian, this basin was flanked, to the south, by a mobile boundary subdivided into fault-blocks (supplying the basin in siliciclastics) and, to the north/north-east, by a much stabler margin (Russe). From Barremian to lower Aptian, an incessant competition occurs between the thick terrigenous basinal sediments (generally external/distal) and the rudist/orbitolinid-bearing "Urgonian-type" carbonate platforms, overlying alignments of shoals (Russe, Lovech, Vratsa, Brestnitsa, Eleshnitsa, Simeonovo), either separated or coalescent. Locally, turbidites with olistolites of Urgonian limestones have been induced by extensional movements, generating sedimentary slopes. During middle/late Aptian, the carbonate platforms drown, then completely disappear and only the terrigenous sedimentation continues within a more and more reduced Axial Basin. During the Albian, the tectonic inversion (first compressions) of the Austrian phase induces the creation of a narrow, but anoxic, foreland basin probably supplied in glaucony by the erosion of hypothetic meridional laterites.
Along a Danube-Gabrovo cross-section, from Central Fore Balkan to Moesian Platform, the Barremian-Aptian deposits are distributed within three distinct paleogeographic domains: a central terrigenous: basin (Pleven-Polski Trămbeš) and, laterally (N: Danube, S: Gabrovo) two carbonate-dominated platforms where “Urgonian” fades can be well-developed. This pattern is induced by synsedimentary extensional tectonics already active from the end of Jurassic times. The subdivision of the various series into eight 3d order depositional sequences and the recent discovery of ammonites allow us to propose new and more reliable correlations between the traditional lithologic formations characterizing those three domains.
The study, in terms of sequence stratigraphy (with ammonite zone control), of numerous cross-sections of Lower Cretaceous (Hauterivian to Aptian) series cropping out along two transects A-B (Fore Balkan and southern part of the Moesian Platform) and C-D (northeastern part of the Moesian Platform) shows the eastwards extension of the North-Tethyan palaeogeographic pattern platform-basin-platform, previously established in central Bulgaria. However, the two boundaryplatforms are strongly assymetrical, this assymetry being revealed by the importance, to the south, of the relative lowstand prograding siliciclastic bodies (supplied by continental erosions linked to extensional tectonics) during the synrift phase (not marked to the north) and by the age, the facies (oolitic to the north, Urgonian to the south) and the number of the calcareous tongues interpreted as the transgressive systems tracts of backstepping depositional sequences, well-marked at the shelf/basin transition.
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