Published online by Cambridge University Press: 09 July 2018
The behaviour of iron in the natural weathering of hornblende in a sedentary soil profile has been investigated using the Mòssbauer effect. The spectra from samples at different stages of weathering show appreciable differences which can be accounted for if ferrous iron is lost preferentially from M(3) sites where it is coordinated to hydroxyl groups in a trans arrangement. Unlike biotite the proportion of ferric iron does not increase during weathering and this illustrates the difficulty with which the ferrous iron is oxidized in the amphibole structure.
On a étudié la conduite du fer dans la dégradation naturelle de la Hornblende dans un profil de sol sédentaire en utilisant l'effet Mòssobauer. Le spectre donne par ces échantillons à différents degrés de dégradation met en relief des différences appréciables dont on doit tenir compte si le fer ferreux est de préférence perdu dans des lieux M(3) où il est égal au groupe Hydroxyle dans une transdisposition. Contrairement à la biolite, la proportion n'augmente pas pendant l'altération ce qui illustre la difflculté avec laquelle le fer ferreux est oxydé dans une structure amphibole.
Das Verhalten von Eisen bei der natiirlichen Verwitterung von Hornblende in einem standorttreuen Bodenprofll wurde mit Hilfe des Mòssbauer- Effekts untersucht. Die Spektra von Probem in verschiedenen Stufen der Verwitterung weisen erhebliche Unterschiede auf, die sich jedoch erklàren lassen, wenn Ferro-Eisen verloren wird, und zwar vor allem von M(3)-Bereichen, in denen es in Trans-Anordnung zu Hydroxylgruppen koordiniert ist. Zum Unterschied von Biotit nimmt der Anteil im Laufe der Verwitterung nicht zu, und dies gibt einen Begriff von der Schwierigkeit, mit der Ferro-Eisen in der Amphibolstruktur oxidiert wird.
Utilizando el efecto Mòssbauer, se ha investigado el comportamiento del hierro en la intemperización naturai de la hornablenda en un perfil del terreno sedentario. El espectro de muestras tomadas a distintas etapas de intemperización muestra diferencias apreciables que pueden ser explicadas si hay pérdida de hierro ferroso preferentemente de sitios M(3), en donde està coordinado a los grupos hidroxilo en una disposición trans. Al contrario que con la biotita, no aumenta la proporción durante la intemperización, y elio ilustra la dificultad con que es oxidado el Fé ferroso en la estructura anfıbólica.
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