Search results for "Marl"
showing 10 items of 66 documents
Changements environnementaux survenant à la limite Oligocène/Miocène du bassin des Limagnes (Massif central, France).
2018
16 pages; International audience; Continental environments are very sensitive to climatic variations. A unique opportunity to study the climate changes around the Oligocene/Miocene boundary is offered by the Limagne graben Basin (France) where this stage boundary is well constrained by fossils. Indeed, some localities of the Limagne Graben Basin are so rich in mammal remains that they have become a European reference for mammal biostratigraphy. The dominant sedimentary facies of the lacustrine deposits in the northern part of the Limagne Graben Basin are composed of poorly cemented marls and calcarenites containing various plants and animals remains (e.g. algae, fish bones and teeth, gastro…
Soil development on sediments and evaporites of the Messinian crisis
2020
Abstract Vast areas in the Mediterranean are characterised by evaporite deposits of the Messinian crises (c. 6–5.3 Ma BP). During this period, large deposits were built up in shallow lagoon-like systems and are now found in southern Italy, Albania, Cyprus and Turkey. So far, soil formation on evaporites has been studied predominantly in subarid to arid environments. Although the formation of soils has received new significance, little is known about the evolutional trajectories on evaporites of the Mediterranean. We therefore studied soil formation in the Caltanissetta basin (Sicily) where evaporites are most widespread. The lithologies included the sequence: marine clay deposits, laminated…
Oligo-Miocene lacustrine microbial and metazoan buildups from the Limagne Basin (French Massif Central)
2018
The Limagne Basin (French Massif Central) is an extensive continental lacustrine system accommodating microbial and metazoan buildups from Chattian to Aquitanian age. A description of these buildups and their associated biotic components in Grand Gandaillat and Crechy quarries provides insights into their spatio-temporal distribution patterns. Flats, cauliflowers, domes, cones and coalescent columnar morphologies have been identified with a main laminated mesofabric and laminated, columnar, filamentous and caddisfly-coated microfabrics. Two low-gradient margin models emerged based on the changes in the distribution, morphology and size of the microbial and metazoan-rich deposits through tim…
Incised valleys and tidal seaways: the example of the Miocene Uzès-Castillon basin, SE France.
2012
Abstract The sedimentology and stratigraphy of the Miocene deposits of the Uzès-Castillon basin are revisited. This basin, located in SE France at the junction between the perialpine foreland basin and the W Mediterranean margin, sits in a syncline that formed during the latest Cretaceous Pyrenean tectonic phase. It records the succession of shallow-water mixed siliciclastic to dominantly bioclastic carbonates that alternate with shelf marls. The clastic carbonates were accumulated as a stack of subtidal dunes and bars that were formed by tidal currents channelized in a seaway following the syncline axis. The marls indicate deposition in more protected and locally deeper waters, as interflu…
Acoustic properties of ancient shallow-marine carbonates: effects of depositional environments and diagenetic processes (Middle Jurassic, Paris Basin…
2010
17 pages; International audience; Examination of petrophysical properties (acoustic velocity, porosity, permeability, and density) and petrographical characteristics (texture, facies composition, and diagenesis) of more than 250 core plugs from the Middle Jurassic carbonates of the eastern Paris Basin provides insights into the parameters controlling acoustic velocities in relatively low-porosity carbonate rocks ({Phi} < 20%). The pore-type observations reveal distinct acoustic velocities in samples with intergranular macropores and samples with micropores in subhedral micrite, such that velocities in microporous mudstone–wackestone (lagoonal) deposits are greater than in macroporous grains…
Occurrence of fossil organic matter in modern environments: optical, geochemical and isotopic evidence
2011
International audience; This study relates to the input and fate of fossil organic matter (FOM) in the modern environment, and focuses on two experimental watersheds overlying Jurassic marls: Le Laval and Le Brusquet (1 km(2) in area), located near Digne, Alpes-de-Haute-Provence, France. Considering that FOM delivery is mainly a result of different processes affecting sedimentary rocks [(bio)chemical and mechanical weathering], samples from different pools were collected: bedrocks, weathering profiles, soils and riverine particles. The samples were examined using complementary techniques: optical (palynofacies methods), geochemical (Rock-Eval 6 pyrolysis, C/N ratio), molecular (gas chromato…
Evidence of aerial volcanic activity during the Valanginian along the northern Tethys margin.
2009
7 pages; International audience; Stratigraphic measurement and sampling on three sections (Vergol, La Charce, and Montclus) through Valanginian deposits from the Vocontian Basin (southeastern France) reveals the occurrence of centimetre thick ochre-coloured layers, which can be correlated from one section to another. At least twelve of these are identified in sediments dated from the Pertransiens to Furcillata ammonite Zones. These horizons appear similar to previously described Oxfordian and Aptian bentonites, also from the Vocontian Basin. Clay-mineralogical and geochemical data are similar in the Valanginian ochre horizons and their enclosing marls except in one of these that shows a cla…
Record of latest Barremian-Cenomanian environmental change in tectonically controlled depressions from the Jura-Burgundy threshold (Jura Mountains, e…
2019
Abstract The area of the western Jura Mountains constitutes the former Jura-Burgundy threshold between the Tethys Ocean and the epicontinental Paris Basin Sea. During the Barremian, the area was covered by a shallow-water Urgonian carbonate platform. Tectonic processes influenced the architecture of the Urgonian platform and were notably responsible for the formation of fault-related depressions on top of the Urgonian series, which were subsequently transformed into incised valleys and then to marine depocenters. Their sedimentary infills are mostly represented by the Perte-du-Rhone Formation and record stepwise environmental change on the innermost platform, which was strongly influenced b…
The relationships between soft-sediment deformation structures and synsedimentary extensional tectonics in Upper Triassic deep-water carbonate succes…
2016
Abstract We describe soft-sediment deformation structures into the Upper Triassic cherty limestone outcropping in the Pizzo Lupo section (Central Sicily, Italy), pertaining to the deep-water palaeodomain of the Southern Tethyan margin. In the study section, mainly consisting of thin-bedded mudstone/marl alternations with bedded chert intercalations, some lithofacies have been separated on the basis of the abundance of the calcium carbonate/clay content and the overall textural features. The deformational structures, displaying different deformational styles as folded and faulted beds, disturbed layers, clastic dikes, and slumps occur mainly in the deformed horizons that involve marl-dominat…
High-resolution clay mineralogy as a proxy for orbital tuning: example of the Hauterivian-Barremian transition in the Betic Cordillera (SE Spain).
2012
11 pages; International audience; The response of clay mineral assemblages to potential orbital forcing is tested in Mesozoic hemipelagic marl- limestone rhythmites of the Río Argos section (Betic Cordillera, Southeastern Spain). Along the section, marls are pervasively enriched in kaolinite and illite, whereas limestones are enriched in smectite-rich illite/smectite mixed-layers, suggesting that marl-limestone alternations are produced by cyclic high-frequency fluctuations of continental runoff. Spectral analyses show that clay mineral assemblages evolve accordingly to precession, obliquity and eccentricity cycles. Durations of ammonite zones are assessed at 535 kyr for the Late Hauterivia…