Richard Ciszak’s research while affiliated with Université Toulouse III - Paul Sabatier and other places

The stratigraphic review and the dating, by means of planktonic foraminifera (Globotruncanidae, Heterohelicidae, “Globigerinidae”), of the main marine Maastrichtian and Paleocene series deposited, in Bulgaria (Fore-Balkan and Luda Kamcija zone), within three paleogeographic domains (foreland turbiditic trough: Emine Formation; hemipelagic basin: Bjala Formation; external/distal-dominated carbonate platform: Mezdra Formation) allow to propose new correlations between the series of the different domains along the North-Tethyan margin. Several features characterize these series: absence of significant lithologic break between Maastrichtian and Danian deposits when they are represented; very local deposition of the Iridium-bearing dark clays underlining the K/T boundary; ponctual evidence of a gap, variable in duration, below and above this boundary (this gap is probably generated by extensional/compressional “laramian” tectonics); diachronism of the glauconitic condensation levels, more or less linked to hard-grounds, which are all included within Paleocene carbonate deposits, various in age, and are never situated at the K/T boundary.

In the Grands Causses, incised valleys, lapies, fissures and sinkholes inherited from successive polyphase karstifications were filled by Palaeocene marine sediments overall assigned to the P1c-P3 interval (Upper Danian-Lower Selandian). These sediments are distributed into three detritic facies, generated by extensional tectonics controlling karstic and erosional processes. Upper Cretaceous marine fossils known within these facies are interpreted as reworked from hypothetically pellicular deposits. The probable palaeogeographic connection with the Pyrenean Palaeocene 'Breccia trough' supposes the presence of a SE-NW 'ria' running across the continental areas of Lower Languedoc and draining towards the northwest the marine waters of the Palaeocene transgression as far as the Rodez region. To cite this article: B. Peybernès et al., C. R. Geoscience 335 (2003).

In the Grands Causses, incised valleys, lapies, fissures and sinkholes inherited from successive polyphase karstifications were filled by Palaeocene marine sediments overall assigned to the P1c–P3 interval (Upper Danian–Lower Selandian). These sediments are distributed into three detritic facies, generated by extensional tectonics controlling karstic and erosional processes. Upper Cretaceous marine fossils known within these facies are interpreted as reworked from hypothetically pellicular deposits. The probable palaeogeographic connection with the Pyrenean Palaeocene ‘Breccia trough’ supposes the presence of a SE–NW ‘ria’ running across the continental areas of Lower Languedoc and draining towards the northwest the marine waters of the Palaeocene transgression as far as the Rodez region. To cite this article: B. Peybernès et al., C. R. Geoscience 335 (2003).

In the Western Fore-Balkan, micropaleontologic assemblages (Calpionellids, benthic Foraminifera, Algae) observed within the lithostratotype ofthe Magura Formation (Magura cave - Rabisha hill, Northern limb of the Belogradchik anticline) evidence its Late Tithonian and Berriasian (Early to Middle) age. This formation can be regarded as a lateral tongue (more or less reefal) of the lower part of the Makresh Fonnation, described in the well R-l, situated more the North, close to the village of Makresh on the Moesian Platfonn. Magura Formation is also older than the "urgonian"-type massive limestones, Barremian in age, from the Oreshets-Rouzhintsi area (SE), previously included in the same formation, which must be rather correlated to the Simeonovo Formation, more the North, and the Banitsa tongue, first unit of the Vratsa Urgonian Group cropping out to the South-East.

In the western Fore-Balkan (northwest Bulgaria), the characterization of numerous depositional sequences within the Barremian–Albian interval allows us to reconstruct from southeast to northwest the successive palaeogeographies of this part of the north Tethyan margin: two carbonate (Urgonian) platforms flanking a central terrigenous basin during the Barremian; a single centrifugal terrigenous basin (Aptian) marked, along its axis, by an olistostrome and siliciclastic turbidites; a single Albian basin characterized by the stacking of glauconite-rich condensation sections and anoxic black marls.

Several exposure surfaces (D1 to D6) underlain by paleo- sols, paleokarstic surfaces, and subsurface paleokarsts were identified in the Middle to Upper Bathonian Calcaires aStipites and Dolomies II Formations in southern France. Two kinds of paleosols with differ- ent degrees of maturity were recognized: simple ferruginous crusts, capping very irregular bed surfaces, and a rooted horizon. The paleo- karstic surfaces are marked by nodular horizons and paleocaves. On the Cevennes shoal, the paleokarsts discontinuities are associated with synsedimentary tectonic processes, which did not extend into the over- lying Dolomies II Formation. Subsurface paleokarsts were observed in the Cirque du Bout du Monde (on the Cevennes shoal) within the Calcaires aStipites Formation, just beneath surface D5. They are char- acterized by stronger brecciation of the beds. Most of the paleokarstic discontinuities described in this study cor- respond to the boundaries of four third-order depositional sequences, Bt 1 to Bt 4 (D1 at the base of Bt 1; D2, D3, D4, and D5 capping Bt 1, Bt 2, Bt 3, and Bt 4, respectively; D6 at the top of the Dolomies II Formation). D1, D2, and D3 paleokarsts are geographically limited to the Grands Causses Graben, whereas D4, D5, and D6 are present only on the Cevennes shoal. Geographic trends of paleokarsts confirm the transgressive trend of sequences Bt 3 and Bt 4, and of the overlying Dolomies II Formation towards the shoal. D6 paleokarstic features were also observed within the uppermost part of the Dolomies II For- mation in the Horst de Saint-Bresson. The latter transgressive process provides evidence for subaerial exposure of this paleostructure during the latest Bathonian-Callovian interval, induced by tectonic uplifts.

This work describes new species of ostracodes collected in the Middle and Upper Bathonian outcrops of the Grands-Causses, Southern France : Kirtonella vignesensis n. sp., Marslatourella bathonica n. sp., Micropneumatocythere montmejeanensis n. sp., Praeschuleridea alzonensis n. sp., and illustrates the predominating species in the assemblages : Limnocythere larzacensis, Theriosynoecum aveyronensis et Fastigatocythere juglandiformis. Ostracode assemblages are characteristic of lacustrine to polyhaline and inner marine environments, and they vary according to changes in salinity, oxygen and trophic level.

This work describes new species of ostracodes collected in the Middle and Upper Bathonian outcrops of the Grands-Causses, Southern France: Kirtonella vignesensis n. sp., Marslatourella bathonica n. sp., Micropneumatocythere montmejeaneansis n. sp., Praeschuleridea alzonensis n. sp., and illustrates the predominating species in the assemblages: Limnocythere larzacensis, Theriosynoecum aveyronensis et Fastigatocythere juglandiformis.Ostracode assemblages are characteristic of lacustrine to polyhaline and inner marine environments, and they vary according to changes in salinity, oxygen and trophic level.