Bernard Peybernès’s research while affiliated with Université de Montpellier and other places

The discovery of a significant assemblage of Paleocene calcareous nannofossils within the turbiditic hemipelagites associated to the debris-flow breccias filling the post-laramian paleokarsts of the Amélie-les-Bains syncline (Eastern Pyrenees) confirms the marine origin of these infillings, as well as their Danian-Selandian age previously suggested on the basis of planktonic foraminifera (Globigerinacea) from the interval sub-zone P1c/ zone P3. The identified nannofloral assemblage, although weakly diversified and not well-preserved, could be assigned to the NP4 (= Ellipsolithus macellus) calcareous nannoplankton zone of Martini, 1971, pointing to the Danian-Selandian transition. Besides the Danian-Selandian taxa, several Cretaceous nannofossils, most probably reworked, are also present in this assemblage. The assemblage is similar to the nannofloras observed within the carbonates of outer/distal shelf facies, Paleocene in age, outcropping at the western extremity of the range in the Basque Country (Zumaya, Hendaye-Loya, Bidart) and Béarn. The complex model of a "Paleocene Pyrenean Trough" is here micropaleontologically reinforced. It encompasses numerous localities, in which Paleocene marine infillings have been characterized and dated by means of their planktonic microfauna, including locally a similar nannoflora (col de Sem, Ariège). Their reinterpretation in the Amélie-les-Bains syncline as "Plio-Quaternary karstic brecciated accumulations" must be rejected.

The discovery of a significant assemblage of Paleocene calcareous nannofossils within the turbiditic hemipelagites associated to the debris-flow breccias filling the post-laramian paleokarsts of the Amélie-les-Bains syncline (Eastern Pyrenees) confirms the marine origin of these infillings, as well as their Danian-Selandian age previously suggested on the basis of planktonic foraminifera (Globigerinacea) from the interval sub-zone P1c/ zone P3. The identified nannofloral assemblage, although weakly diversified and not well-preserved, could be assigned to the NP4 (= Ellipsolithus macellus) calcareous nannoplankton zone of Martini, 1971, pointing to the Danian-Selandian transition. Besides the Danian-Selandian taxa, several Cretaceous nannofossils, most probably reworked, are also present in this assemblage. The assemblage is similar to the nannofloras observed within the carbonates of outer/distal shelf facies, Paleocene in age, outcropping at the western extremity of the range in the Basque Country (Zumaya, Hendaye-Loya, Bidart) and Béarn. The complex model of a “Paleocene Pyrenean Trough” is here micropaleontologically reinforced. It encompasses numerous localities, in which Paleocene marine infillings have been characterized and dated by means of their planktonic microfauna, including locally a similar nannoflora (col de Sem, Ariège). Their reinterpretation in the Amélie-les-Bains syncline as “Plio-Quaternary karstic brecciated accumulations” must be rejected.

Late Jurassic platform carbonates of Languedoc (southern France) are deeply incised by Late Miocene canyons, allowing the observation of karst systems filled with sediments containing evidences of marine origin. Field and structural relationships as well as new biostratigraphic data (planktonic foraminifera and calcareous nannofossils) provide a Latest Cretaceous-Earliest Paleocene age for the major karstification and a Paleocene (Danian-Selandian) age for the sedimentary filling. The ≥ 350 m vertical extend of this karst system and its subsequent marine filling gives a minimum amplitude for the base-level variation responsible for the karstification then marine flooding event. The observations suggest that at least two marine successive events occurred in the Late Danian then in Selandian time. The large amplitude of base level is not in agreement with eustatic sea-level change, and the rate of base-level change is too fast for tectonic uplift and subsidence within the tabular, poorly deformed, studied area. We propose a model of a silled endoreic basin, which was desiccated and karstified over hundreds of meters, when it was disconnected from the World Ocean, and later brutally transgressed by the Paleocene sea, and the karst flooded, when the bounding sill was submerged. Such a model is similar, although with significant differences, with the later Messinian-Zanclean event that affected the Mediterranean realm.

The Latest Cretaceous/Paleocene paleokarsts from Bas-Languedoc (South of France) are characterized by : 1) exokarstic paleosurfaces (sink holes, pinnacles, canyons) which are mostly superimposed onto the Late Jurassic limestones and partly filled up with breccias and sandy clays containing Paleocene planktonic foraminifera; 2) endokarstic cavities filled up by sandy pelites and laminated mudstones with similar micropaleontological assemblage. All these cavities constitute three cut-and-filled paleokarstic systems. A general model of formation for this polyphase system is proposed. These paleosurfaces are generated by a Latest Cretaceous tectonic phase and Paleocene movements associated with eustatic rises inducing rapid floodings. During Upper Danian-Lower Selandian times three successive base levels drops, whose cumulated duration could be as long as 3 Ma, have induced several hundred metres of incisions within the exposed Jurassic carbonate series. A paleogeographic reconstruction shows three main marine gulfs which extend towards NE the EW Pyrenean thrust belt (“Pyrenean Paleocene Trough”, PPT) located on the axis of the future Pyrenees. The similarity of the facies and micropaleontological content in the two domains suggests connexions between the marine Paleocene deposits of Bas-Languedoc and the PPT. It could thus explain the succession of the same tectono-eustatic events. We propose, as an hypothesis, that the rapid sea-level changes, as recorded by the imbricated karstic paleomorphologies, could be induced by the closing and the opening of a strait in the Eastern part of the PPT acting as a sill. This would be controlled by tectonic movements along the active orogenic axis of the Pyrenean Range and eustatic variations of the Paleocene World Ocean. The karstic systems developed during these low-stand episodes may have been later reactivated after the Early Selandian and more specifically during the Messinian desiccation event. This late evolution may have generated deep flooded karsts, now situated below the present sea level. Such karsts, partly inherited from Paleocene, could be important aquifers of economic interest.

The Mesozoic series of the southern units of the Pyrenean Empord thrust sheets (Montgri and Figueres nappes, Catalonia, Spain) were finally emplaced over the autochthonous basement and its Cenozoic cover during Eocene times. However, they have originally been folded by the "Laramian" compressional event (Late Cretaceous/Early Paleocene), while they were still in their root zone more than 50 km to the N-NE. Postdating the Santonian, the emersion of the Cretaceous tectorogen induced karst formation at the expense of Berriasian to Santonian limestone sequences. Karst cavities of this paleokarst 1 (lapiaz and canyons) were subsequently coated with a fine, red or black, Microcodium-bearing, continental silt, and infilled with marine chaotic breccias. Following a new episode of emersion then erosion, the original paleokarst 1 was cross-cut by newly formed cavities of the paleokarst 2, filled with Lutetian-Bartonian marine breccias. Both types of marine breccias (Paleocene then Eocene in age) are now relatively well dated by means of planktonic foraminifera (Globigerinacea) occurring within the argillaceous-sandy matrix, and for the older ones, within the argillaceous-sandy or carbonate, finely laminated, interbedded hemipelagites, that mark the top of marine sequences tens of centimetres thick. The relationships of the "Laramian" and "Pyrenean" compressional tectonic events, occurring from latest Cretaceous to Bartonian, with the development of pateokarsts 1 and 2 are analysed in the perspective of the progressive southwards emplacement of the Montgri thrust sheet, during Eocene time.

The planktonic Foraminifera from the Palaeocene breccias of the Tardets area (‘Zone des Chaînons Béarnais’, Pyrenées-Atlantiques, France). Palaeocene marine breccias, the so-called ‘Etchebar/Bosmendiette breccias’, from the area of Tardets (Zone des Chaînons Béarnais, Pyrenées-Atlantiques, France) are interpreted as gravitational deposits (debris-flow) overlying a folded Jurassic and Early Cretaceous carbonate substrate and overlain, in turn, by the karstified rims of palaeocanyons, which, on the axis of the future range, were excavated during the “Laramide” orogenic phase at the end of the Cretaceous and the beginning of the Palaeocene. We clarify the cartographic, sedimentologic and petrographic characteristics of these breccias in this paper. Early/Middle Palaeocene (Late Danian–Early Selandian, P1c-P3 zonal interval) pelagic assemblages of ‘Globigerinacea’ are identified from new thin-section samples in their argillaceous carbonate matrix as well as within interbedded hemipelagites. These breccias are now well known and well dated along the Pyrenees from the ‘Corbières’ (to the east) to the Marble Thrust Sheet (to the west). The hypothesis of their diapiric origin founded on their supposed Aptian age must be consequently definitely rejected. To cite this article: M.-J. Fondecave-Wallez et al., C. R. Palevol 5 (2006).

The cartographic, sedimentological and micropalaeontological analysis of remnants of Middle–Upper Cretaceous turbiditic basins from the ‘Pays de Sault’ (Aude, French Pyrenees) shows their diachronism (interpreted on a wider scale) and their sequence diversity. The ‘Gesse breccias’ are regarded as the proximal deposits of a Turonian narrow foreland basin, principally supplied by the erosion of the Jurassic–Lower Cretaceous cover of the High Primary Range to the south, induced by a strike-slip and overthrusting faulting within the en-échelon North-Pyrenean Fault Zone. More to the north, the North-Pyrenean ‘Axat Basin’ consists of two successive backstepping turbiditic wedges, respectively corresponding to an Upper Albian distal flysch and to a Middle–Upper Cenomanian more proximal flysch, all the series unconformably overlying structures that were folded then eroded before the Upper Albian. The previous concept of carbonate olistoliths included within the Axat Cenomanian flysch is also refuted: these large-size blocks are now interpreted as belonging to a tectonic slice destroyed and partly collapsed on the southern slope of the Rebenty Valley during the Quaternary. To cite this article: M.-J. Fondecave-Wallez, B. Peybernès, C. R. Geoscience 336 (2004).

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 Eastern part of French Pyrenees, the Cucugnan area (Southern Corbières) corresponded during the early/Mid-Paleocene (Danian/Selandian) to a narrow transitional zone between the sea to the South (“Pyrenean Paleocene Trough”) and the continent (fluvio-palustrine and lacustrine “Vitrollian” deposits) to the North. To the South, in the North-Pyrenean Zone, the polygenic marine breccias and the associated Dano-Selandian Globigerinid-bearing hemipelagites have been preserved within successive paleokarsts superimposed onto the carbonate substratum (ante-Albian). Four paleosurfaces are recognized, principally filled by marine internal sediments with proximal and distal facies. To the North, in the “Sub-Pyrenean Zone”, a continental foreland basin is characterized by four formations of variegated Microcodium-bearing marls and channelized conglomerates, separated by erosional paleosurfaces underlining well-marked unconformities. An event correlation (chronodiagrams) between the marine realm to the South and the continental realm to the North is proposed, using the successive paleosurfaces and the lithological sequences (same number within the two realms). Our paleogeographic reconstruction shows, to the North, the “Lake of Cucugnan” and, to the South, a calcareous mountainous zone broken by the juxtaposition of deep paleocanyons (eroded in a continental context) later converted into rias submitted to marine oscillations. Several palinspastic transects are reconstructed: they show the polyphase control of the Frontal North-Pyrenean Overthrust on the Paleocene sedimentation and the importance of the successive intra-Vitrollian compressions/ transpressions (“phase fini-crétacée” auct.) inducing, within the two juxtaposed realms, emersions, erosions and karstic features which give a very contrasted paleogeography during a period characterized by plate convergence and creation of steep topographies.

Within the Emerici zone–Barremense zone biostratigraphic interval, the Barremian deposits of Central Fore-Balkan (Lovech–Veliko Tarnovo shelf) consist of a succession of several formations where alternate terrigenous argillaceous/sandy-dominated facies (Kormjansko Fm., Balgarene Fm.) and carbonate-dominated (‘Urgonian’) facies (Krushevo Fm., Emen Fm.). The qualitative and, particularly, quantitative facies analysis of the carbonate successions observed along 13 detailed cross-sections and in one drill hole show the stacking of about 40 fifth-order T–R cycles induced by numerous eustatic jerks contributing to the progressive settlement of this shelf. These high-frequency cycles of about 100000 years must be regarded as valuable correlation tools for the subsurface hydrocarbon research. To cite this article: V. Minkovska et al., C. R. Geoscience 336 (2004).