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| Registros recuperados: 35 | |
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| Quantin, Paul; Zebrowski, Claude. |
| This study concerns the indurated horizons of some volcanic ash soils in the Interandine Valley of the Ecuador. These indurated horizons were cropped out by erosion on the piedmont of the sierras, under a subarid to subhumid climate, and then they have been called cangahua. The soils within they are intercalated are composed of several various pyroclastic deposits. The soil profiles show one, two or several indurated horizons. The present observations concern a soil climo-toposequence near Bolivar, viz: downward a soil profile with 2 cangahua horizons; at the midslope a profile with only one horizon of weathered tuff; a little above, another soil with a weakly weathered consolidated ash fall layer; and finally, at the summit on the paramo, an andosol... |
| Tipo: Text |
Palavras-chave: CENDRE VOLCANIQUE; PYROCLASTITE; INDURATION; TOPOSEQUENCE; CHIMIE DU SOL; MINERALOGIE; PETROGRAPHIE; CANGAHUA. |
| Ano: 1997 |
URL: http://www.documentation.ird.fr/hor/fdi:010012912 |
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| Colmet-Daage, François; Besoain, E.; Gautheyrou, Jacques; Gautheyrou, Michèle; Delaune, Mireille; Shenkel, G.; Fusil, Ginette; Kimpe, C. de; Trichet, M.; Sieffermann, Gaston; Yoshinaga, N.; Schnitzer, M.; Bernard, J. (ill.); Laugenie, C.. |
| Tipo: Text |
Palavras-chave: CENDRE VOLCANIQUE; PEDOGENESE; SOL; TYPOLOGIE; CARACTERISTIQUE PHYSIQUE; CARACTERISTIQUE CHIMIQUE; ARGILE; MINERALOGIE; CARACTERISTIQUE HYDRIQUE. |
| Ano: 1974 |
URL: http://www.documentation.ird.fr/hor/fdi:29901 |
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| Hidalgo, C.; Quantin, Paul; Elsass, F.. |
| The tepetates of Mexico Highlands are indurated horizons with fragipan pr0perties. Tepetates appear among pyroclastic deposits (T1, T2, T3). A soil profile located near Texcoco, Mexico, including tepetate layers was studied. Mineralogical and microscopical features of this profile were studied using a series of methods. This report the main results of the study. Tepetates were characterized by several features: first, the nature of their parent material; second, a close matrix microstructure and third, their colloidal fraction. The latter is conformed mainly by laminated 1:1 to 2:1 mixed layer minerals made of flaky layers. These features can explain the fragipan properties of tepetates and most of their mechanical behaviour. (Résumé d'auteur). |
| Tipo: Text |
Palavras-chave: SOL; INDURATION; CENDRE VOLCANIQUE; PYROCLASTITE; HORIZON; MINERALOGIE; METHODE D'ANALYSE; TEPETATE. |
| Ano: 1997 |
URL: http://www.documentation.ird.fr/hor/fdi:010012913 |
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| Lorenzoni, P.; Quantin, Paul; Spadoni, M.. |
| In the sedimentary basin of Rieti (Central Italy) a Mollic Fragiudalf was studied in order to verify, through the analysis of differential dissolution kinetics of Si and Al, wether the presence of this two elements could be involved in determining the fragic characters of its deep horizons. The reuslts of the main physico-chemical analysis confirmed the fragic features of the deep horizons Bt3x and Ctgx which have been already observed in the field study. Differential dissolution of Si and Al was performed using 0,5 N NaOH at 25°C, and the values of silica and alumina obtained after each of ten consecutive extractions were cumulated to trace the cumulative curves of dissolution. Slope changes of the curves, which indicate changes in dissolution rate,... |
| Tipo: Text |
Palavras-chave: CENDRE VOLCANIQUE; HORIZON; ALUMINIUM; SILICE; MINERALOGIE; PYROCLASTITE; FRAGIPAN. |
| Ano: 1997 |
URL: http://www.documentation.ird.fr/hor/fdi:010012917 |
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| Wiart, Pierre. |
| L'impact de deux volcans sur l'environnement a été étudié : celui de Tanna et la reprise d'activité du Lombenben à Aoba. Totalement différents, ces deux volcans ont un impact indéniable sur la forêt et les jardins des habitants. Le Yasur émet des gaz et des cendres provoquant des pluies acides, pouvant détruire le milieu végétal et créer des disettes occasionnelles. La "crise d'Aoba" (mars 95) a provoqué la destruction du milieu végétal de l'ensemble de la caldeira, par le dégazage intense de gaz acides et toxiques au travers du lac de cratère Voui. De plus les risques d'éruption à moyen terme ne semblent pas écartés, et restent toujours un danger pour la population locale. (Résumé d'auteur) |
| Tipo: Text |
Palavras-chave: VOLCANISME; LAVE; COULEE; CENDRE VOLCANIQUE; SEISME; CATASTROPHE NATURELLE; PLUIE ACIDE; PREVENTION DES RISQUES. |
| Ano: 1995 |
URL: http://www.documentation.ird.fr/hor/fdi:43111 |
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| Registros recuperados: 35 | |
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