Lower Burdigalian Research Articles

Provenance and paleogeographic implications for the Cenozoic sedimentary cover of the Ghomaride Complex (Internal Rif Belt), Morocco

The Cenozoic sedimentary cover from the Ghomaride Complex (Internal Rif Belt) has been studied in the Tetuan area (N Morocco) where a suite of sedimentary successions from shallow-marine to deep-marine environments crops out. For that purpose stratigraphic relations and petrological and geochemical signatures have been analyzed. Sandstone suites of the overall succession are heterogeneous and testify a multi-source area, in response of accretionary processes of the Ghomaride-Maláguide units and the exhumation of the lower units of the Internal Rif Zone (e.g. Sebtide-Alpujárride Complex). Pre-orogenic and Syn-orogenic (according to the eoalpine phase) deposits have been identified consisting in two depositional sequences: lower Paleocene and Cuisian-Bartonian, and upper Oligocene-upper Aquitanian and lower Burdigalian, respectively. Pre-orogenic deposits are mainly intra-arenite and hybrid arenites made of a minor amount of siliciclastic detritus but with abundance of intrabasinal carbonate grains. The syn-orogenic sandstone suites are quartzolithic, having abundance of low-grade metamorphic and sedimentary lithic fragments. Sedimentary lithic fragments are derived from the Mesozoic successions of the Ghomaride-Maláguide Complex while metamorphic detritus is related to an unknow Internal Rif Zone basement that was exhumed starting from the late Oligocene and mainly early Miocene. Modal analyses of sandstone suites for the extrabasinal grains mainly indicate lower rank metamorphic and sedimentary source terranes of a recycled orogen. Major and trace elements coupled to the mineralogical composition of the mudrock samples indicate a provenance from felsic source area(s) with a minor but not negligible contribution from mafic rocks mainly in the syn-orogenic suites. Geochemical analyses (Al–Ti–Zr ternary plot) indicate minor reworking and recycling processes before the final deposition through prolonged processes of sedimentary transportation. The trends evident in both CIA and CIA’ diagrams indicate source areas characterized by moderate weathering in non-steady-state conditions with a weak change of weathering condition from the pre-orogenic to the syn-orogenic cycle. Deposition during the Paleocene and Eocene, took place in the southern continental margin of the Ghomaride-Malaguide domain as a carbonate ramp. Contrarily, sedimentation in the late Oligocene-late Aquitanian took place in wedge-top basins within the Ghomaride-Malaguide domain. These changes occurred during the Burdigalian, when back arc basins were developed in the Internal Betic-Rif Zone. The Cenozoic reconstructed record was contemporaneous of the structuring of the Circum-Mediterranean chains and the Ghomaride-Maláguide Complex played a key role in the geodynamic evolution of the Rif Cordillera, representing a key tectonic element of the western Mesomediterranean domains.

Coastal sandy spit deposits (Lower Burdigalian/Eggenburgian) in the Alpine-Carpathian Foredeep of Lower Austria

In the type-area of the Eggenburgian regional stage (Lower Burdigalian) sands with large-scale clinoforms were studied north-west of Eggenburg (Lower Austria). Stratigraphic and facies architecture, palaeocurrent pattern and inferred palaeogeographic setting show that these sands are deposits of W–E trending and SW to SSE prograding coastal spit systems, attached to crystalline shoals or islets in the shallow marine Eggenburg Bay. The spits were dominantly formed by shoal parallel accretion above fair-weather wave base due to longshore transport. The 4–5 m thick clinoforms with bottomset, foreset and topset structures contain up to 3.6 m thick, steeply inclined foresets, dominated by sediment gravity-flow deposition. Relatively stable depositional conditions, characterized by strong unidirectional currents, high sand supply and sufficient accommodation space are assumed for their formation. However, internal reactivation surfaces indicate variations in current activity, orientation and velocity. The deposits of spit systems are interpreted as part of a transgressive systems tract. The provenance analysis reveals the local Moravian and Moldanubian crystalline rocks as principal source. The spit sands of the Burgschleinitz Formation show the highest mineralogical maturity within the studied Lower Miocene succession. Intense reworking and redeposition of material from older deposits is evident. Due to the ongoing transgression deposits of the following Gauderndorf Formation and Zogelsdorf Formation exhibit a larger catchment area with input of high amounts of fresh weathered material.

Calappilia erwinhartei, a new calappid crab (Crustacea, Decapoda) from the Lower Miocene of Portugal

A new species of the box crab Calappilia A. Milne-Edwards in de Bouillé, 1873 from lower Burdigalian (Lower Miocene) strata at Penedo Norte (Aldeia do Meco, Setúbal, Atlantic Coast of Portugal) is described and named. This new record increases the known diversity and palaeo-geographical distribution of the genus and sheds additional light on its migratory and evolutionary pathways.

New species of Acasta and Balanus (Balanoidea: Acastinae, Balaninae) from the Early Miocene (Burdigalian) of the Aquitaine Basin, France

Two new species of spiny barnacles (Balanoidea: Acastinae, Balaninae) are described from the lower Burdigalian (Early Miocene) of the Aquitaine Basin, southwest France. The first, Acasta martillacensis sp. nov., from Martillac, is characterised by a shell with internal longitudinal ribs, a cellular space between the sheath and wall, a carinal sheath which adheres to the wall in the centre of its basal edge, a cup-shaped basis and a scutum with radial striae externally and a less than prominent adductor ridge internally. The second, Balanus aculeatus sp. nov., from Saucats (Le Péloua), has paries exteriorly with strong, tubular spines. An overview of outcrops of Burdigalian strata in the area, within a palaeogeographic context, is added.

A new Early Miocene genus of the family Sciaenidae (Teleostei, Perciformes) from the eastern Paratethys

A new genus of sciaenid fish Caucasisciaena is erected to accommodate the Early Miocene eastern Paratethys species Perca ignota Smirnov, 1936, which, subsequently, was variously attributed to the modern genera, either Larimus or Otolithoides. The materials examined include 32 specimens from four Caucasian and Crimean localities of Sakaraulian age (Lower Burdigalian). The new genus is based on a unique combination of features, including: parasphenoid with a dorsal rounded bony flange; basisphenoid present; premaxilla with short ascending process forming obtuse angle with alveolar process and ascending/alveolar process ratio about 0.17; anterior premaxillary teeth enlarged; posttemporal with few robust spines along its posterior margin; presence of 25 vertebrae; presence of three tiny supraneurals; dorsal fin with 11 spines plus 22–24 soft rays; anal fin with two spines and 7–8 soft rays; second anal-fin spine long and massive; pectoral fin elongate; scales ctenoid on body and cycloid on head (except for one or two rows of ctenoid scales on the cheek). Paleoecological considerations suggest that Caucasisciaena probably was a predatory fish that inhabited the coastal waters of the eastern sector of the Paratethyan basin.

Évolution morphostructurale du plateau volcano-sédimentaire de Gergovie au Miocène inférieur : implications géodynamiques sur la phase tardi-tectonique du rift de Limagne (Massif central, France)

The Gergovie plateau is a Lower Miocene topographically inverted volcano-sedimentary system located in the monogenetic volcanic field of the Limagne rift Tertiary basin. It is composed of three east–west aligned maars partly covered by a basaltic lava flow. The eruption of the central maar (maar 1) occurred at the Oligocene–Miocene transition, during the first volcanic phase. This phreatomagmatic structure was almost totally cut through by the opening of a second maar (maar 2) during the next eruptive phase. The basaltic lava flow at the summit and the eastern maar (maar 3) were placed during a third and last eruptive phase during the Middle or Upper Burdigalian (∼19–16 Ma). Between these periods of volcanism, three fluvial to fluviolacustrine sedimentation episodes, separated by two erosive stages, followed one another. A bedrock thickness of 100–300 m was eroded from maar 2 during the upper Aquitanian and (or) the lower Burdigalian (∼22–19 Ma). This erosion is partly due to a volcano-tectonic uplift in the southern Limagne. The complex morphostructural evolution of the Gergovie plateau demonstrates the north–south geodynamic differentiation of the Limagne rift during the Lower Miocene, since the northern part of the basin corresponded to a relatively calm lacustrine sedimentation area. More generally, the Miocene volcanic field in the South of the Limagne gives an opportunity to study interactions between volcanism, tectonics, and erosion during the late passive rifting activity phase.

Chronostratigraphy and paleomagnetism of Oligo-Miocene deposits of Corsica (France) : geodynamic implications for the liguro-provençal basin spreading

Abstract In a context of convergence between Africa and Europe, the western Mediterranean domain is characterized by the opening of the Liguro-Provençal ocean in the early Miocene and of the Tyrrhenian Sea since the middle Miocene. These openings are preceded by an Oligocene rifting episod. New biostratigraphic, geochronologic and paleomagnetic data allow to propose an integrated stratigraphy sketch for the Oligo-Miocene period in Corsica. The continental syn-rift deposits, in the region of Ajaccio, have been dated as late Chattian from the presence of a mammal, Pomelomeryx boulangeri. Their paleomagnetic study indicates an anticlockwise rotation of 44 ±4° with regard to the stable Europe. The early Miocene succession was deposited on a contrasted topography inherited from the Oligocene glyptogenesis period. The lowermost Miocene deposits are represented by 4 pyroclastic flow deposits in southern Corsica. New 40Ar-39Ar datings on plagioclase concentrates give ages between 21.3 and 20.6 Ma (late Aquitanian). Paleomagnetic directions indicates that the rotation of Corsica had probably begun at this time. The Miocene marine sediments of the Bonifacio basin are divided in two formations. At the base, the Cala di Labra formation, that comprises 3 reef formations in coastal onlap (R1, R2, R3), is attributable to the Globigerinoides trilobus zone. In the environment of R1, miogypsin population includes mainly Miogypsina intermedia with a few M. globulina and M. cushmani. The absence of the less evolved forms (10 < V < 35) let us suppose that at least the lower Burdigalian is absent at Bonifacio because the region was emerged. R2 reef has a similar population (42 < V < 70), which suggests a rather short interval of time between the two stages of reef construction. On the other hand the R3 population contains only evolved forms (M. mediterranea) suggesting a late Burdigalian age. The end of the sedimentary succession (Bonifacio formation) is essentially represented by a pile of hydraulic dunes. The absence of Orbulina shows that this upper unit is older than late Langhian (biozone N9). Miocene sediments from Saint-Florent are divided into 3 marine formations bracketed by two continental ones. At the base, the continental formation of Fium’Albinu (equivalent to the Cala di Labra formation) is surmounted by the Torra formation attributed to Late Burdigalian based on the presence of G. trilobus and G. bisphericus. The Sant’Angelo formation (equivalent to the Bonifacio formation) developed from latest Burdigalian to late Langhian. The Farinole formation represents early Serravallian (base of the Globoquadrina altispira altispira zone). Despite the large number of studied sites in this study and others, the only reliable Oligo-Miocene paleomagnetic results in Corsica are the following ones : – the Vazzio formation indicates a rotation of 44 ± 4° after the late Oligocene, – the southern volcanic flows show that the rotation was in progress around 20.7 Ma (late Aquitanian), – the Fium’Albinu formation indicates a rotation of 30 ± 12° after early Burdigalian, – site B from Vigliotti and Kent [1990] gives a rotation of about 11 ± 5° after early Langhian. Our paleomagnetic data, together with the existing ones, associated to the biostratigraphic and geochronologic ages show that the opening of the Ligurian basin coincides with an anticlockwise rotation of 45° of Corsica, which begins between 23 and 21 Ma and ends around 15 Ma. This is in agreement with the idea of Sardinia and Corsica rotating as a single almost rigid block during Miocene times.

The Lozère sands and the Sologne sands : two detrital discharges in the Paris basin during the early Miocene. New interpretations

Abstract Following a review of the previous interpretations concerning the drainage pattern modifications of the Loire-Seine in the Paris basin, this work attempts to show the chronological and distributional relations between the Lozère sands and the Sologne sands. Heavy mineral analyses of about 300 samples, extracted from sands of a series of outcrops and drill holes from the detrital deposits coming from the Massif Central and located between the Nivernais and the Pays de Caux, makes it possible to separate the Lozère sands and the Sologne sands (fig. 1 and tabl. I). The first deposits show analogies with the Albian sands, having poor mineralogical variety and containing only a few feldspars, whereas the second ones incorporate greater mineralogical variety and more feldspars (fig. 2). The identification of Lozère sands outcrops in the Loire valley, south of the Sologne area (fig. 3) proves that a palaeo-Loire-Seine existed before the discharge named Sologne sands during the Lower Burdigalian. A tectonical evolution (fig. 4) is proposed to explain the changes in mineralogy and distribution of the deposits. The progressive uplift of the northern border of the Massif Central caused the erosion of the Albian sands which contributed to the fluvial discharge of the Lozère sands. But when the Ligerian depression extended to the Sologne area, the fluvial discharge diverted toward the Atlantic, the Albian sands being excluded from erosion, and the Sologne sands were mainly supplied by basement derived alterites showing a greater mineralogical variety. Since the Burdigalian, the Loire and the Seine basins had a distinct evolution. While the Sologne sands were buried under the Bourbonnais sands, the augite river deposits and the Lozère sands were reworked on the polygenic erosional surface [Dewolf et Pomerol, 1997] which developed from late Burdigalian to early Pleistocene times, before the Quaternary incision of the rivers.

Application of Sr isotope stratigraphy and sedimentary analysis to the origin and evolution of the Neogene basins in the Isparta Angle, southern Turkey

Four Miocene basins are located within the Isparta Angle in southern Turkey. One of these, the Dariören Basin, is well established as the foreland basin to the adjacent Lycian Nappes which marks the western margin of the Isparta Angle. The tectonic origin of the other three basins (Aksu, Köprü and Manavgat) has remained enigmatic largely because of the difficulties of dating the lowermost part of the succession (continental and shallow-marine conglomerates and limestones). Comparison of carbonate 87Sr/ 86Sr with the ocean water Sr isotope record provides a powerful chronological tool for marine sediments. By using Sr isotope ratios in this way, ages of the neritic limestones have been derived despite the absence of age-diagnostic fossils. These data constrain the age of the underlying conglomerates as lower to middle Burdigalian. The timing of deepening and subsidence events suggested by these new dates, taken together with palaeocurrent measurements from conglomerates, suggest that the basin configuration of the Isparta Angle was initiated in the lower Burdigalian and was directly related to movement on north–south-oriented faults. Depocentre development in the north of the Aksu Basin is consistent with a tectonic origin for all three basins by flexurally induced block faulting of the foreland in front of the Lycian Nappes along pre-existing structural weaknesses.

Mineralogía de los materiales de la Formación de La Viñuela (Cordilleras Béticas)

Mineralogy of several samples from the Vinuela Formation,Lower Burdigalian (Velez Malaga, Cordilleras Beticas), has been studied. Materials are composed of abundant microfauna. and pebbles of micaschits, quartzites and other materials, from the Alpujarrides and Malaguides Nappes, cemented by a micritic matrix . Most samples contain zeolites (clinoptilolite, mordenite and analcime), and illite chlorite, interstratified clay minerals, montmorillonite and opal C-T. A diagenetic genesis for zeolites is suggested.

Contribution to a geodynamic synthesis of the Provençal Basin (North-Western Mediterranean)

A set of seismic and field data has been recently collected from the Provençal Basin and Sardinia which makes it possible to ascertain the extension of the oceanic floor in the Gulf of Lions and in the Ligurian Sea, and to date oceanic accretion between the Upper Aquitanian and the Lower Burdigalian. These data provide a general framework for interpretation of the magnetics in the basin according to the Vine and Matthews hypothesis. Kinematics of the drifting of Corsica and Sardinia are discussed on the basis of this analysis, and the processes of oceanic accretion are examined. The attempt is made to compare these mechanisms with those reported in the marginal seas of the Western Pacific.

Les series transgressives d'age oligo-miocene inferieur de l'Apennin meridional; consequences tectoniques et paleogeographiques

Abstract Uppermost Stampian-lower Aquitanian, upper Aquitanian (lower Burdigalian), tectonic events, shale blocks, foraminifera