Search results for "genesis"
showing 10 items of 12136 documents
Geodynamic control on carbonate diagenesis: Petrographic and isotopic investigation of the Upper Jurassic formations of the Paris Basin (France).
2007
23 pages; International audience; The Oxfordian and Kimmeridgian carbonates of the eastern edge of the Paris Basin display poor reservoir properties (Φb15% and Kb0.1 md). The petrographic investigation and the resultant paragenetic sequence show that this is due to extensive precipitation of 2 types of almost synchronous blocky LMC (Low Magnesian Calcite) cements during mesogenesis (burial). Stable isotope investigation of these non-recrystallized cements, through both microdrilling sampling and in-situ SIMS (Secondary IonMass Spectrometry) analysis, shows that they originated from slightly buffered meteoric fluids (−3‰SMOW to −8‰SMOW) flowing through the Malm carbonate aquifers of the east…
Controlled treatment of a high velocity anisotropic aquifer model contaminated by hexachlorocyclohexanes
2020
International audience; Xanthan gels were assessed to control the reductive dechlorination of hexachlorocyclohexanes (HCHs) and trichlorobenzenes (TCBs) in a strong permeability contrast and high velocity sedimentary aquifer. An alkaline degradation was selected because of the low cost of NaOH and Ca(OH)2. The rheology of alkaline xanthan gels and their ability to deliver alkalinity homogeneously, while maintaining the latter, were studied. Whereas the xanthan gels behaved like non-Newtonian shear-thinning fluids, alkalinity and Ca(OH)2 microparticles had detrimental effects, yet, the latter decreased with the shear-rate. Breakthrough curves for the NaOH and Ca(OH)2 in xanthan solutions, ca…
The Early-Cambrian Boho volcano of the El Graara massif, Morocco: Petrology, geodynamic setting and coeval sedimentation
2006
15 pages; International audience; A major volcanic episode is recorded across the Neoproterozoic-Cambrian transition in the Moroccan Anti-Atlas. Several volcanic cones are still preserved in the El Graara massif, laterally correlatable with volcanic flows dated as Early Cambrian (U/Pb date of 534 ± 10 Ma). Volcanic ashes and flows are interbedded with the uppermost part of the Adoudou dolostones, whereas the best-preserved volcano (the Boho Jbel) is onlapped by the overlying Lie-de-vin strata. Available petro-geochemical data from the Boho volcano suggest an alkaline magmatism probably derived from low-grade melting of a garnet–lherzolite mantle source, followed by fractional crystallizatio…
Textural-chemical changes and deformation conditions registered by phyllosilicates in a fault zone (Pic de Port Vieux thrust, Pyrenees)
2017
International audience; Synkinematic phyllosilicates in fault zones can be used to deduce the deformation mechanisms and the conditions of fault activity, as their chemical composition, crystal structure and texture can record the different stages of deformation and fluid-rock interactions. The Pic de Port Vieux, a second-order thrust related to the major Gavarnie thrust in the southern central part of the Pyrenees Axial Zone, juxtaposes Triassic pelites of the hanging wall and Cretaceous limestones of the footwall. In order to investigate the mineralogical and geochemical changes and constrain the deformation conditions of thrusting, characterization of phyllosilicates was performed along …
Progress on bringing together raptor collections in Europe for contaminant research and monitoring in relation to chemicals regulation.
2019
Paola Movalli et al.
Tectonics of the Northern Bresse region (France) during the Alpine cycle
2003
International audience; Combining fieldwork and surface data, we have reconstructed the Cenozoic structural and tectonic evolution of the Northern Bresse. Analysis of drainage network geometry allowed to detect three major fault zones trending NE-SW, E-W and NW-SE, and smooth folds with NNE trending axes, all corroborated with shallow well data in the graben and fieldwork on edges. Cenozoic paleostress succession was determined through fault slip and calcite twin inversions, taking into account data of relative chronology. A N-S major compression, attributed to the Pyrenean orogenesis, has activated strike-slip faults trending NNE along the western edge and NE-SW in the graben. After a tran…
Methane production and oxidation potentials in relation to water table fluctuations in two boreal mires
1999
We studied the response of methane production and oxidation potentials in a minerotrophic and an ombrotrophic mire to water table fluctuations. In profiles where water table had not varied, the water-saturated layers showed significant potentials while the unsaturated layers did not. The production potentials in the saturated layers below water level ranged from 0.1 to 2.4 m gC H4 h ˇ1 (g d.w.) ˇ 1 and oxidation potentials (first order reaction rate constants) betweenˇ0.010 andˇ0.120 h ˇ1 (g d.w.) ˇ 1 . In profiles with constant water level, the maximal production potential occurred 20 cm and maximal oxidation potential 10 cm below water level. When water table varied only a little, product…
Volatile Profiles of Emissions from Different Activities Analyzed Using Canister Samplers and Gas Chromatography-Mass Spectrometry (GC/MS) Analysis: …
2017
The objective of present study was to identify volatile organic compounds (VOCs) emitted from several sources (fuels, traffic, landfills, coffee roasting, a street-food laboratory, building work, indoor use of incense and candles, a dental laboratory, etc.) located in Palermo (Italy) by using canister autosamplers and gas chromatography-mass spectrometry (GC-MS) technique. In this study, 181 VOCs were monitored. In the atmosphere of Palermo city, propane, butane, isopentane, methyl pentane, hexane, benzene, toluene, meta- and para-xylene, 1,2,4 trimethyl benzene, 1,3,5 trimethyl benzene, ethylbenzene, 4 ethyl toluene and heptane were identified and quantified in all sampling sites.
The chronic effects of fullereneC 60 -associated sediments in the midge Chironomus riparius – Responses in the first and the second generation
2017
Abstract The life cycle parameters of the benthic invertebrate Chironomus riparius make it a relevant organism for use in multi-generation chronic ecotoxicology tests. Since studies on chronic exposures with fullerene carbon nanoparticles have revealed adverse effects at lower concentration ranges, it is crucial to gain understanding of the consequences in following generations. The aims of this study were to investigate whether sediment-associated fullereneC 60 impacts on C. riparius emergence and breeding, thus affecting the growth of the second generation. Larvae were exposed to fullerene-spiked sediment at concentrations of 0.5, 10 and 40 mg/kg sediment dw. Total emergence and breeding …
Landscape instability at the end of MIS 3 in western Central Europe : evidence from a multi proxy study on a Loess-Palaeosol-Sequence from the easter…
2019
Abstract The Lower Rhine Embayment hosts important Loess-Palaeosol-Sequences (LPS) within the western European loess belt yielding valuable information on landscape evolution and palaeoclimatic dynamics. The study focusses on the palaeoenvironmental development based on a LPS from the eastern shoulder of the Lower Rhine Embayment (Dusseldorf-Grafenberg). The palaeoenvironmental development within the study area is presented and discussed based on high-resolution grain size analyses, selected environmental magnetic parameters, and geochemical analyses complemented by luminescence age estimates. Differences in grain size distribution (ΔGSD) as well as the U-ratio clearly reflect main stratigr…