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Soil organic carbon stock on the Majorca Island: temporal change in agricultural soil over the last 10 years
2019
8 Pags.- 5 Tabls.- 3 Figs.
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…
A record of seafloor methane seepage across the last 150 million years
2020
<p>Methane seepage at the seafloor is a source of carbon in the marine environment and has long been recognized as an important window into the deep geo-, hydro-, and bio-spheres. However, the processes and temporal patterns of natural methane emission over multi-million-year time scales are still poorly understood. The microbially-mediated methane oxidation leads to the precipitation of authigenic carbonate minerals within subseafloor sediments, thus providing a potentially extensive record of past methane emission. In this study, we used data on methane-derived authigenic carbonates to build a proxy time series of seafloor methane emission over the last 150 My. We quantitat…
Increase inabovegroundfreshlitterquantityover-stimulatessoil respiration inatemperatedeciduousforest
2010
In the context of climate change, the amount of carbon allocated to soil, particularly fresh litter, is predicted to increase with terrestrial ecosystem productivity, and may alter soil carbon storage capacities. In this study we performed a 1-year litter-manipulation experiment to examine how soil CO2 efflux was altered by the amount of fresh litter. Three treatments were applied: litter exclusion (E), control (C, natural amount: 486 g m −2 ) and litter addition (A, twice the natural amount: 972 g m −2
Environmental change during the Early Cretaceous in the Purbeck-type Durlston Bay section (Dorset, Southern England): a biomarker approach.
2007
20 pages; International audience; The Purbeck-type section (Durlston Bay, Dorset, UK) exhibits littoral lagoonal to lacustrine facies. It shows a gradual climatic/environmental change from semi-arid conditions associated with evaporites at the Jurassic–Cretaceous transition, to a more humid climate at the end of the Berriasian. Though generally organic-poor (total organic carbon, TOC, <1.3%), the Durlston Bay section shows an organic-rich episode (TOC up to 8.5%) located at the transition from evaporitic to more humid facies. A biomarker study was performed in order to determine the origin of the organic matter (OM) in the section and see if changes in organic sources accompanied the genera…
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…
Impact of basin burial and exhumation on Jurassic carbonates diagenesis on both sides of a thick clay barrier (Paris Basin, NE France).
2014
27 pages; International audience; Several diagenetic models have been proposed for Middle and Upper Jurassic carbonates of the eastern Paris Basin. The paragenetic sequences are compared in both aquifers to propose a diagenetic model for the Middle and Late Jurassic deposits as a whole. Petrographic (optical and cathodoluminescence microscopy), structural (fracture orientations) and geochemical (δ18O, δ13C, REE) studies were conducted to characterize diagenetic cements, with a focus on blocky calcite cements, and their connection with fracturation events. Four generations of blocky calcite (Cal1-Cal4) are identified. Cal1 and Cal2 are widespread in the dominantly grain-supported facies of t…
Using Optical and Thermal Data for Tracking Snowmelt Processes in Alpine Area
2019
Alpine catchments represent a fundamental reservoir of fresh water at midlatitude. Remote sensing offers the opportunity to estimate snow properties in the optical, thermal and microwave domains. In particular, the possibility to estimate snow density from remote sensing is relevant and still represents a great challenge for the remote sensing scientific community. Since changes of snow density and liquid water content occur continuously in the snowpack, spatial and temporal patterns of optical and thermal data can give information about snowmelt processes. The main goal of this study is to evaluate if snow thermal inertia can be an indicator of snowmelt processes and to evaluate its relati…
Validation of HF radar sea surface currents in the Malta-Sicily Channel
2019
Abstract A network of High-Frequency radar (HFR) stations runs operationally in the Malta-Sicily Channel (MSC), Central Mediterranean Sea, providing sea surface current maps with high temporal (1 h) and spatial (3 × 3 km) resolutions since August 2012. Comparisons with surface drifter data and near-surface Acoustic Doppler Current Profiler (ADCP) observations, as well as radar site-to-site baseline analyses, provide quantitative assessments of HFR velocities accuracy. Twenty-two drifters were deployed within the HFR domain of coverage between December 2012 and October 2013. Additionally, six ADCP vertical current profiles were collected at selected positions during a dedicated field survey.…
Petrographic and geochemical characterization of the Middle‒Upper Jurassic Fe–Mn crusts and mineralizations from Monte Inici (north-western Sicily): …
2021
AbstractFe–Mn concretions and mineralizations, associated with condensed horizons and hardground, are significant archives in ancient carbonate rocks. Their petro-chemical study allows an assessment of the palaeoenvironmental context in which they were formed also connected to their biotic or abiotic origin. At the western side of the Monte Inici (Fornazzo section, north-western Sicily) a well exposed outcrop of condensed pelagic limestones (Rosso Ammonitico facies: Middle‒Upper Jurassic) is well-known and thoroughly studied. In this section, the base of the Rosso Ammonitico facies consists of a very condensed level rich in fossils with a variable thickness deposited from the early Bathonia…