Caractérisation des mortiers anciens

National audienceBoukhara (Ouzbékistan) a plus de 2 500 ans d'histoire, patrimoine mondial par I'UNESCO en 1994. Elle est l'exemple le plus complet d'une ville médiévale d'Asie centrale dont la structure urbaine est restée jusqu'au XIX° siècle essentiellement intacte, avec de nombreux monuments dont les célèbres Médersas du XIV°. Les mortiers de plusieurs parties de la Médersa Rachid de Boukhara (Ouzbéhstan), ont été caractérisés ainsi que les aspects technologiques impliqués dans les processus de fabrication des mortiers en Ouzbékistan. Il ne suffit pas de définir de l'état de dégradation de ces mortiers mais aussi donner outils pour les futures restaurations de la Médersa Rachid. La cathédrale métropolitaine de Florianopolis est considérée comme un patrimoine culturel du XVII° siècle, liée à la fondation du village de Nossa Senhora do Desterro. Pendant 230 ans, elle a subi de nombreuses transformations architecturales. La chapelle a été construite par Francisco Dias Velho en 1651 puis transformée 1721. Jose da Silva Paes brigadier-général a ordonné la restauration et l'agrandissement de l'Église en 1748. Au début du XX° siècle l'Église est devenue cathédrale. En 1922, le projet du XVIII° siècle a été modifié et la structure pariétale de l'Eglise a reçu une transformation notable, notamment l'élévation des clochers et les ajouts décoratifs. Lors de la restauration effectuée en 2005, ont été découverts des fresques du XVIII° siècle et de 1938. Le château de Roche la-Molière (près de Saint Etienne, France) est nommé pour la première fois dans l'acte notarié du Forez-Lyonnais en 1173. M. Lavieu est le premier propriétaire connu. En 1772, le marchand Jacques Neyron a acheté le château et il a fait un travail considérable. Le château est complet et admirablement conservé, a été entièrement restauré en 2003. Nous avons pu suivre les travaux et caractériser les différents types de mortiers et enduit

Phosphoric acid extraction and rare earth recovery from apatites of the Brazilian phosphatic ores

National audienceVarious experiments led in laboratory on the concentrate of Angico dos Dias phosphate allowed us to define the following steps in the process of hydrochloric treatment: 1 - Acidification of the concentrate by HCl at 20% during two hours at ambient temperature (solid/liquid ratio of 40%, agitation speed of 200 rpm). In these conditions, the solubilisation rates of CaO and P2O5 are commonly superior to 95% (around 80% for (REE)2O3) ; 2- Precipitation, at ambient temperature, of Na2SiF6 after the addition of a sodium salt to the chlorophosphate solution. The precipitate gotten reveal that more than 80% of the fluorides, initially present in the phosphate rock, can be recovered as sodium fluorosilicates ; 3 - Liquid-liquid extraction of the phosphoric acid by the tributylphosphate. The aqueous phase obtained is treated by ammonia so as to precipitate the rare earth elements as a phosphate concentrate. The application of the process practically does not allow the formation of residues or liquids. The (REE) recovery rate of 80% constitutes a valorization source of the proposed process

Lixiviation du béton et son incidence sur l'environnement

National audienceL'objectif de ce travail est d'étudier le comportement du béton dans un environnement de lessivage important à travers le comportement de certains éléments. Pour ceux, nous avons mis en place un protocole de lixiviation de matériau broyé par une solution d'eau pure de pH 6 (représentatif de celui d'une eau de pluie) en système fermé. L'importance des constructions en béton et la pollution atmosphérique importante provoquant un lessivage permanent de ces matériaux de construction, justifie cette étude. La présence dans les produits de fusion des fourneaux des cimentiers de plus en plus de métaux qui se trouvent incorporer dans le ciment milite également pour ce travail

The impact of a uranium mining site on the stream sediments (Crucea mine, Romania)

XRF methods were used to evaluate the impact of uranium mine dumps on the stream sediments from Crucea region (Romania). In order to estimate the natural and anthropogenic inputs of radioactive and heavy metals in the sediments, normalization to Al was applied. The pollution degree of the bottom sediments show that U, Th and Pb reach medium and punctual high values, while the rest of the elements appears in concentrations close to the background or lower. The measurements carried out in the surroundings of a local uranium mine show that the impact of Crucea mine on water quality downstream of mining area is insignificant

The impact of an uranium mining site on the stream sediments (Crucia mine, Romania)

International audienceXRF methods were used to evaluate the impact of uranium mine dumps on the stream sediments from Crucea region (Romania). In order to estimate the natural and anthropogenic inputs of radioactive and heavy metals in the sediments, normalization to Al was applied. The pollution degree of the bottom sediments show that U, Th and Pb reach medium and punctual high values, while the rest of the elements appears in concentrations close to the background or lower. The measurements carried out in the surroundings of a local uranium mine show that the impact of Crucea mine on water quality downstream of mining area is insignificant

Ages constraints in pegmatite province related to charnockitic host rocks in Minas Gerais, Brazil

National audienceCambrian-Neoproterozoic granitoids suites in southeastern Brazil are the main host rocks of largest pegmatite field of Brazil, the Eastern Pegmatite Province. The P-Li-Nb pegmatites group represent the richest in precious stones like Beryl, Aquamarine, Topaz and Tourmaline. Two types of pegmatites are characterized by their mineralogical characteristics and tectonic and magmatic relations. The first group formed during compressive event about 582 Ma and the second pegmatite group was formed by cooling of residual melts during the transition to an extensional phase (520-500Ma) of the Brasiliano/Pan-African Orogeny, related to metamorphic rock melts (gneiss migmatite, gneiss) and extensive granite-charnockite emplacement. The new charnokite isotopic data presented here constrain the latest pegmatite genesis at about 500 Ma as its maximum age

Petrografia e Geoquímica do Complexo Charnockítico de Aimorés: Um Exemplo de Plutonismo Pós-orogênico do Cinturão Araçuaí/Ribeira =Petrography and Geochemistry of the Aimorés Charnockitic Complex: An Example of Post-orogenic Plutonism of the Araçuaí/Ribeira Belt

http://geologiausp.igc.usp.br//downloads/geoindex767.pdfInternational audienceO Complexo Aimorés corresponde a um corpo multi-intrusivo anelar com cerca de 150 km2 de exposição. Possui características pós-orogênicas e exibe zonas de misturas de magma no contato e no interior do corpo. O complexo é constituído de monzodioritos no centro, com um anel intermediário de charnockitos, circundado por granodioritos. Há ocorrências menores de leucogranitos com granada. São abundantes enclaves básicos e intermediários, de diferentes tamanhos e formas. O contato com a encaixante é de alto ângulo e mostra-se concordante e discordante. Nas rochas encaixantes predominam gnaisses de fácies anfi bolito a granulito. As diversas fácies do complexo são meta-aluminosas, exceto os leucogranitos e os megaenclaves que são peraluminosos. O índice de saturação em alumina é ao redor de 1 e o índice de agpaicidade ((Na+K)/Al) situa-se entre 0,45 e 0,77. Nos diagramas de Harker, a correlação negativa de CaO, MgO, Fe2O3, TiO2 e P2O5 pode ser explicada principalmente pelo fracionamento de piroxênio e feldspato. A razão MgO/TiO2 próxima a 1 é compatível com granitoide tardi a pós- -colisional. As razões Ba/Sr, Zn/MgO, Sr/Rb e Ba/Rb indicam fracionamento importante promovido inicialmente por piroxênio e plagioclásio e depois por anfi bólio, biotita e feldspato de potássio. Os dados geoquímicos parecem refl etir a combinação de processos de cristalização fracionada e/ou de contaminação crustal e de mistura de magmas. =The Aimorés Complex is an inversely zoned multistage ring-like structure which crops out over about 150 km2 and was intruded approximately 500 Ma years ago, during the post-collision event related to Araçuai-Ribeira Fold Belt. This complex consists of a monzodioritic core with hypersthene, and a charnockitic intermediary ring encircled by granodiorites. The contact between core and rim is marked by a mingled/mixed zone, where small occurrences of garnet-granite were also found. Abundant enclaves of different shapes and sizes occur showing circular, diffuse and sharp contacts with the groundmass. The contact with the country rocks is sharp and sub-vertical, varying from concordant to discordant and presenting dips toward the intrusion. The enclosing rocks are orthogneiss, which have experienced high-amphibolite to granulite-facies metamorphism. Most of the facies of the complex are metaluminous, except for the large enclaves embedded in the inner portion, which are peraluminous. The aluminium saturation index is approximately 1 and the agpaitic index ((Na+K)/Al) ranges from 0.45 to 0.77. The negative correlation of CaO, MgO, Fe2O3, TiO2 e P2O5 in the Harker diagram can be explained by pyroxene and feldspar fractionation. The MgO/TiO2 ratio close to 1 and the tectonic discrimination diagrams are compatible with postcollisional granitoids, as well as the sum of Zr, Nb, Ce and Y (500 - 1.000 ppm). The Ba/Sr, Sr/Rb, Ba/Rb and Zn/MgO ratios indicate that there was initially fractionation by pyroxene and plagioclase, followed later by fractionation by amphibole, biotite and K-feldspar. Geochemical data probably refl ects the combination of crystal fractionation and/or crustal contamination and magma mingling/mixing processes

REE minerals in Catalão II, Goias, Brazil

National audienceThe REE minerals pyroxenites and sövites of Catalão II show a substantial enrichment in REE from the magmatic stage. The activity of carbonate and CO32-/ PO43- ratio have played an important role in the formation of REE-carbonate-phosphates, which are an intermediate form between REE-rich apatite and REE-rich carbonate. The magmatic enrichment in REE and Ti, favored by the presence of a carbonate phase, correlate to a high activity of CO32- and activities of Ti and Na specially in the carbonatite. This feature explains the low enrichment in phosphate (apatite vein) in Catalão II compared to Catalão I, which is rich in apatite vein. In the weathering stage, these minerals interact with the fluid surface and lose some of their REE and Ba. The exchange reactions between pyrochlore and ground water are generally consistent with relatively low pH, low activities of Na+, Ca2+, F-and elevated activities of Ba2+ /or Ce3+. Significant amounts of Ba were derived from barite dissolution with some silicate contribution, whereas the Ce might come, either from dissolved REE-carbonate minerals or from the pyrochlore themselves through selective immobilisation of Ce as Ce4+

Impact of heavy metals in sewage sludge on soil and plants (colza and wheat)

National audienceWe are testing the impact of heavy metals in sludge from urban and industrial wastewater treatment plants. We try to understand their influence on plant growth and their bioaccumulation. We chose two plants: the wheat and rapeseed to their specific characteristics; wheat is a herbaceous low accumulator of heavy metals, however rape (colza) is a plant of the family Brassica napus, is an excellent bio-accumulator of heavy metals. The mean levels found in the soil are organized in the following order: Fe >> Mn> Zn> Pb> Cu> Ni> Co> Cd. The contents of heavy metals in the sludge is made very high and exceed European values allowed for that type of use but remain in the standard NT106 Tunisia. The effects of the contribution of sludge are manifested by a significant increase in the weight gains of the whole plant, these results in a variation of the ratio between the aerial part and roots of the plant; this ratio tends to increase with dose of mud brought in soil increase. The roots of both plants show high levels of Zn even on the ground untreated control. The contents of Ni, Pb and Zn compared to Cu and Co are higher in the roots of rape than wheat

Apoptose du colza induite par de fortes doses de boues industrielles issues de station d'épuration

National audienceCette étude préliminaire consiste à évaluer sur le colza les effets de l'épandage des boues industrielles chargées en métaux lourds surtout en plomb et chrome. Nous nous sommes intéressés aux fortes doses d'épandage 100tnia pour mieux observer les phénomènes de transformations induites sur le colza par l'absorption des métaux lourds. Nous avons utilisé la technique ultra structurale pour l'observation en microscope électronique à transmission