Search results for "Structural basin"
showing 10 items of 292 documents
Proposal for the Thuoux section as a candidate for the GSSP of the base of the Oxfordian stage.
2012
20 pages; International audience; The Thuoux section, located in South-Eastern Basin of France (coordinates: 44°30'55"E; 5°42'25"N), is a section that satisfies numerous demanding criteria as reference section (GSSP) for the base of the Oxfordian stage. Sedimentation was continuous in that the abundant ammonitic fauna yields no detectable hiatuses. The stratigraphic boundary is located between the Lamberti Zone and the Mariae Zone or more precisely between the Paucicostatum horizon (MARCHAND, 1979) and the Thuouxensis horizon (FORTWENGLER & MARCHAND, 1994a). In this section, there is a perfect mixing bet-ween Boreal ammonites (Cardioceratinae) whose species are used as stratigraphic markers…
Variations in Jurassic echinoid biodiversity at ammonite zone levels: Stratigraphical and palaeoecological significance
2020
After a relatively low but stable phase of taxonomic diversity during the Lias (Lower Jurassic), echinoids diversity strongly increases from Aalenian (Dogger-Middle Jurassic) to Kimmeridgian (Malm-Late Jurassic) and a conspicuous crisis takes place in Tithonian times, before the end of the Jurassic. During these major phases, minor decreases in diversity correspond with regressions (sea-level falls), mainly in the Middle Bathonian (Middle Jurassic). From the Aalenian to Callovian, the average duration of irregular echinoid species is about 3.8 m.y. whereas it is about 5.5 m.y. for the regular ones; the later value corresponding to the average duration of a Jurassic. From Callovian to Tithon…
Albian ammonites of the Benguela Basin (Angola): a biostratigraphic framework.
2007
20 pages; The study of the Albian ammonite fauna of the sedimentary series in the Benguela Basin (Angola) allows a major revision of the biostratigraphy of the south Atlantic area. The new biostratigraphic approach allows the recognition of 17 horizons distributed in 8 subzones correlated with the ammonite zonation of the Tethyan Province. The Lower Albian is characterized by the Douvilleiceras inaequinodum Subzone (including the D. mammillatum aequinodum Horizon). The Middle Albian is represented by the Oxytropidoceras (Mirapelia) buarquianum Subzone (subdivided into O. (M.) buarquianum and O. (M.) sergipense horizons). The Upper Albian is characterized by the Dipoloceras sp. Subzone (defi…
Settlement down again patterns of a carbonated platform following up a sedimentary crisis : example of the middle-late Jurassic boundary in the south…
2004
Abstract Following a sedimentary crisis which begins in the late Lower Callovian and spans all the early Oxfordian, the settlement down patterns of a platform with carbonated sedimentation are analysed in a southeastern area of the Paris Basin (fig. 1). Ten lithostratigraphic units (reefal formations, associated bioclastic facies and marly distal lateral facies ; fig. 2) are defined (fig. 3). New ammonite and brachiopod faunas, collected in situ, allow to date accurately the sedimentary units with a precision matching an ammonite subzone of the standard bio-chronostratigraphic scale (fig. 4) of the middle-late Oxfordian (from the Parandieri Subzone, at the base of the Transversarium Zone, t…
The earliest tupilakosaurid amphibian with diplospondylous vertebrae from the Late Permian of southern France
2007
5 pages; International audience; A well-preserved vertebral column from the Late Permian of Southern France (Lopingian, La Lieude Formation, Lodève Basin) is described. It is composed of diplospondylous vertebrae and is most comparable with the temnospondyl Tupilakosaurus previously known from the Early Triassic of Greenland and Russia. This new specimen therefore represents the earliest occurrence of a diplospondylous tupilakosaur, and extends the geographic range of the group to Western Europe. It is an aquatic temnospondyl that used the anguilliform undulatory mode of swimming.
Microcrinoids from the lower and middle Albian of the Anglo-Paris Basin (southern England, UK, Seine Maritime, Pas de Calais and Aube, France).
2021
16 pages; International audience; Microcrinoids of the family Roveacrinidae Peck, 1943 are described from lower and middle Albian clays of the Anglo-Paris Basin (Seine Maritime, Pas de Calais and Aube, France; Kent and Bedfordshire, UK). They are referred to two subfamilies - the Orthogonocrininae Gale, 2019 and the Plotocrininae Gale, 2020. Orthogonocrinines include the long-ranging (middle Albian-lower Cenomanian) species Orthogonocrinus apertus Peck, 1943, and Styracocrinus peracutus (Peck, 1955), known from Texas, USA, Morocco, the UK and France, and two stratigraphically successive species of the genus Hyalocrinus, H. magniezii Destombes, 1984 and H. bulliensis Destombes, 1984, known o…
Segmentation and differential post-rift uplift at the Angola margin as recorded by the transform-rifted Benguela and oblique-to-orthogonal-rifted Kwa…
2010
29 pages; International audience; We analyse tectonic and sedimentary field and subsurface data for the Angola onshore margin together with free-air gravity anomaly data for the offshore margin. This enables us to characterize the mode of synrift tectonism inherited from the Precambrian and its impact on the segmentation of the Angola margin. We illustrate that segmentation by the progressive transition from the Benguela transform-rifted margin segment to the oblique-rifted South Kwanza and orthogonal-rifted North Kwanza margin segments. The spatial variation in the intensity of post-rift uplift is demonstrated by the study of a set of geomorphic markers detected in the post-rift succession…
Orbital chronology of the lower-middle Aptian: palaeoenvironmental implications (Serre Chaitieu section, Vocontian Basin).
2013
4 pages; International audience; A detailed cyclostratigraphic study conducted on several proxies including spectral gamma ray, magnetic susceptibility, clay minerals, and carbonate content suggests that the return to equilibrium in the carbon cycle after the major disturbance linked with Oceanic Anoxic Event 1a occurred in about 2 Myr. The minimum duration of the D. furcata zone is estimated at 0.46 Myr and that of the E. subnodosocostatum zone at 1.45 Myr. Strengthening of the obliquity record in the furcata zone confirms the cooling that characterizes this period.
A later fifth-millennium cal BC tumulus at Hofheim-Kapellenberg, Germany
2020
In the nineteenth century, two Neolithic axe-heads were reported from the Michelsberg enclosure system at Kapellenberg. The recent identification of an unusually large tumulus, from which the axe-heads were almost certainly once recovered, reveals that socio-political hierarchisation, linked to the emergence of high-ranking elites in Brittany and the Paris Basin during the fifth millennium cal BC, may have extended into Central Europe.
Temple-complex post-dates tsunami deposits found in the ancient harbour basin of Ostia (Rome, Italy)
2015
Abstract Detailed geophysical and geoarchaeological investigations carried out in Ostia, ancient harbour of Rome, revealed two different generations of harbour basins and also proved the repeated impact of high-energy wave events on the study area. West of Ostia, at the southern bank of the Tiber, a lagoonal harbour existed from the 4th and 2nd cent. BC but was affected by strong siltation. At the same site, a river harbour was subsequently established from the 1st cent. AD onwards. Fluvial deposits of medieval age finally document Tiber river bank erosion affecting the abandoned site. Within the sedimentary record, distinct high-energy event deposits were found and seem to be related to ts…