Search results for " mineral"
showing 10 items of 541 documents
CHLORITE/SMECTITE - ALKALI FELDSPAR METASOMATIC XENOLITHS FROM HYBLEAN MIOCENIC DIATREMES (SICILY, ITALY): EVIDENCE FOR EARLY INTERACTION BETWEEN HYD…
2006
Upper-Miocene tuff-breccia pipes from the Hyblean area (south-eastern Sicily) bear a number of ultramafic and mafic xenoliths (spinel-peridotites, pyroxenites, gabbroic rocks) whose study has led to conclude that the Meso-Caenozoic carbonatic and volcanic succession stands upon a fossil oceanic core-complex, probably connected with the adjacent Ionian crust. Evidence for hydrothermal metasomatism is common in the Hyblean ultramafic and mafic xenoliths. In some cases, extreme metasomatic transformation and shearing have deleted original mineralogy and textures yielding unusual rocks, hereafter called “metasomatites”. These rocks generally exhibit cataclastic texture, their hydrothermal miner…
Análisis litoestratigráfico del keuper urpirenaico central
2004
Joaquin.Bastida@uv.es Se ha estudiado la litoestratigrafía del Keuper surpirenaico central en los afloramientos de dos sectores: las Sierras Marginales (sector sur) y Les Nogueres (sector norte). En el Keuper de las Sierras Marginales se han distinguido tres unidades litológicas: Formación Yesos de Canelles, Formación Yesos de Boix y Formación Arcillas y Carbonatos de Les Avellanes, con una potencia conjunta de 200 a 400 m. En el Keuper de Les Nogueres se han distinguido cuatro unidades litológicas: Formación Arcillas y Carbonatos de Adons, Formación Yesos de Boix, Formación Yesos de Senterada y Formación Arcillas y Carbonatos de Les Avellanes, con una potencia conjunta de más de 200 m. Las…
Comparison of different tillage systems in organic farming : effect of soil structure and organic matter repartition on soil micro-organisms and thei…
2009
Over the last decades, the surface traditionally ploughed has tended to decrease and replaced by shallow working tillage techniques without soil inversion, i.e., no tillage or reduced tillage with tines or discs. These techniques were mostly developed in conventional farming systems but nowadays they are also developed in organic farming systems. Nevertheless, these tillage techniques could generate crop nutrients deficiencies and a deterioration of soil structure, especially during the first years of their application. As the use of synthetic fertilizers is forbidden in organic farming, a decrease of the soil fertility could be very detrimental for crop growth. Indeed, soil micro-organisms…
Effect of timing of grassland destruction on nitrogen mineralization kinetics.
2007
International audience
Atmospheric radiative effects of an in-situ measured Saharan dust plume and the role of large particles
2007
This work will present aerosol size distributions measured in a Saharan dust plume between 0.9 and 12 km altitude during the ACE-2 campaign 1997. The distributions contain a significant fraction of large particles of diameters from 4 to 30 μm. Radiative transfer calculations have been performed using these data as input. Shortwave, longwave as well as total atmospheric radiative effects (AREs) of the dust plume are investigated over ocean and desert within the scope of sensitivity studies considering varied input parameters like solar zenith angle, scaled total dust optical depth, tropospheric standard aerosol profiles and particle complex refractive index. The results indicate that the lar…
Typology of exogenous organic matters based on chemical and biochemical composition to predict potential nitrogen mineralization
2010
Our aim was to develop a typology predicting potential N availability of exogenous organic matters (EOMs) in soil based on their chemical characteristics. A database of 273 EOMs was constructed including analytical data of biochemical fractionation, organic C and N, and results of N mineralization during incubation of soil–EOM mixtures in controlled conditions. Multiple factor analysis and hierarchical classification were performed to gather EOMs with similar composition and N mineralization behavior. A typology was then defined using composition criteria to predict potential N mineralization. Six classes of EOM potential N mineralization in soil were defined, from high potential N minerali…
Effect of temperature on soil microbial structure and fractionation during C mineralisation
2008
International audience; Microbial carbon mineralization in soils leads to the production of different gaseous or dissolved components that have environmental impacts. Our study deals with the influence of soil temperature on the production of gaseous and dissolved carbon components during carbon mineralization in forest soils in France. After an incubation of soil samples for 42 days at 4 different temperatures, we determined both size and 13C isotopic signature of dissolved organic carbon and CO2 pools. We also characterised the soil microbial community structure (PLFA profiles). While temperature clearly increases the CO2 production, a low decrease of the dissolved organic carbon pool was…
Relation entre les sols de la région manganésifère de Moanda (Gabon, Afrique de l'Ouest) et les terrils pisolitiques issus de l'activité minière
2007
National audience
Spatial variability of isoproturon mineralizing activity within an agricultural field: geostatistical analysis of physicochemical and microbiological…
2007
International audience
13C differentiation of dissolved organic carbon pool during carbon mineralization in soil from a native deciduous forest and a coniferous plantation
2007
International audience