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Role of Iron Reduction in The Conversion of Smectite to Illite in Bentonites in the Disturbed Belt, Montana

Published online by Cambridge University Press:  01 July 2024

Eric Eslinger ,
Patrick Highsmith ,
Doyle Albers  and
Benjamin deMayo
Eric Eslinger
Affiliation:
Department of Geology, West Georgia College, Carrollton, Georgia 30118
Patrick Highsmith
Affiliation:
Department of Geophysical Sciences, Georgia Institute of Technology, Atlanta, Georgia 30303
Doyle Albers
Affiliation:
Department of Geology, University of Idaho, Moscow, Idaho 83843
Benjamin deMayo
Affiliation:
Department of Physics, West Georgia College, Carrollton, Georgia 30118
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Abstract

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Cretaceous bentonites were collected in outcrop from the Sweetgrass Arch and the Disturbed Belt in Montana. The mixed-layer illite-smectite (I/S) components of the bentonites from the Sweetgrass Arch have from 0 to 25% illite layers and no detectable structurai Fe2+, whereas the samples from the Disturbed Belt have from about 25 to 90% illite layers, and all contain Fe2+. A positive correlation (r = 0.89) exists between the percentage of structural iron that is Fe2+ and the amount of fixed interlayer K in the I/S.

The higher percentage of illite layers in the samples from the Disturbed Belt is attributed to reactions related to elevated temperatures caused by burial beneath thrust sheets. The increase in Fe2+/Fe3+ with increasing percentages of illite layers is tentatively attributed to a redox reaction involving the oxidation of organic matter. Although there is no statistical evidence for an increase in octahedral charge with an increase in illite layers when all the samples are considered together, iron reduction may have contributed as much as 10 to 30% of the increase in total structural charge that occurred in any given sample during metamorphism. The remaining structural charge increase can be attributed to the substitution of Al3+ for Si4+ in the tetrahedral sites.

Резюме

Резюме

Бентониты мелового периода были собраны в обнажениях Свитграс Арк и Дистербд Белт в Монтане. Смешанно-слойные компоненты бентонитов иллит-смектит (И/С) из Свитграс Арк имеют 0 до 25% слоев иллита и в них не было обнаружено структурного Fе2+, тогда как пробы из Дистербд Белт имеют примерно от 25 до 90% слоев иллита, и все содержат Fе2+. Положительная корреляция (г = 0,89) существует между процентным содержанием структурного жедеза (Fе2+) и количеством фиксированного межслоя К в И/С.

Большое процентное содержание слоев иллита в пробах из Дистербд Белт относится за счет реакций, присходящих при повышенных температурах, обусловленных залеганием бентонитов под надвиговыми пластами. Увеличение Fе2+/Fе3+ с повышением процентного содержания слоев иллита, на основе опыта, связывается с окислительно-восстановительной реакцией, включающей окисление органического материала. Хотя при рассмотрении всех образцов не существует статистических доказательств увеличения октаэдрического заряда с увеличением содержания слоев иллита, восстановление железа могло обусловить от 10 до 30% увеличения общего структурного заряда, который возник в каждом образце в течение метаморфизма. Остающееся увеличение структурного заряда может быть отнесено за счет замещения Аl3+ кремнием Si4+ в тетраэдрических слоях.

Resümee

Resümee

Kreidehaltige Bentonite wurden in Zutageliegen vom “Sweetgrass Arch” und “Disturbed Belt” in Montana gesammelt. Die Illit-Smektit (I/S) Anteile der Wechselschicht der Bentonite vom “Sweetgrass Arch” haben von 0 bis 25% Illitschichten und kein feststellbares strukturelles Eisen2”1”, wohingegen die Proben vom “Disturbed Belt” ungefähr von 25 bis 90% illitschichten haben und alle enthalten Eisen2+. Eine positive Abhängigkeit (r = 0,89) besteht zwischen dem Prozentsatz des strukturellen Eisen, welches als Eisen2”1” vorkommt und der Menge der gehärteten Zwischenschicht K im I/S.

Der höhere Prozentsatz von Illitschichten in den Proben vom “Disturbed Belt” wird Reaktionen zugeschrieben, die mit erhöhten Temperaturen verbunden sind, die durch Vergrabung unter Schubschichten erzeugt wurden. Die Zunahme in Eisen2+/Eisen3+ mit zunehmendem Prozentsatz von Illitschichten wird versuchsweise einer Redoxreaktion zugeschrieben, in der Oxidation von organischem Material beteiligt ist. Wenn alle Proben zusammen berücksichtigt werden, gibt es keine statistischen Beweise für die Zunahme in oktaedrischer Ladung mit Zunahme in Illitschichten. Eisenreduktion könnte jedoch soviel wie 10 bis 30% zu der Zunahme in gesamtstruktureller Ladung, welche in jeder gegebenen Probe vorkommt, beitragen. Der Rest der strukturellen Ladungszunahme kann der Substitution von Si4+ mit Al3+ in den tetraedrischen Plätzen zugeschrieben werden.

Résumé

Résumé

Des bentonites du Crétacé ont été collectionés d'un affleurement de Sweetgras Arch et du Disturbed Belt du Montana. Les constituants illite-smectite à couches mélangées (I/S) des bentonites de Sweet-gras Arch ont de 0 à 25% de couches d'illite et pas de Fe2+ détectible, alors que les échantillons du Disturbed Belt ont de 25 à 90% de couches d'illite, et tous contiennent Fe2+. Une corrélation positive (r = 0,89) existe entre le pourcentage de fer de composition qui est Fe2+ et la quantité de K fixe intercouche dans I/S.

Le pourcentage plus élevé des couches d'illite dans les échantillons du Disturbed Belt est attribué à des réactions liées à de hautes températures causées par l'enterrement sous des nappes de charriage. L'augmentation de Fe2+/Fe3+ allant de pair avec l'augmentation des pourcentages des couches d'illite est tentativement attribué à une réaction rédox impliquant l'oxidation de matière organique. Bien qu'il n'y ait aucune évidence statistique d'une augmentation de charge octaèdrique accompagnant une augmentation dans les couches d'illite lorsque tous les échantillons sont considérés ensemble, la réduction de fer peut avoir contribué de 10 à 30% à l'augmentation de la charge totale de composition qui s'est passée pendant le métamorphisme de tout échantillon. Le reste de l'augmentation de charge de composition peut être attribué à la substitution d'Al3+ à Si4+ dans les sites tétraèdriques.

Keywords

BentoniteIlliteIron reductionMixed layerMontanaSmectite
Type
Research Article
Information
Clays and Clay Minerals , Volume 27 , Issue 5 , October 1979 , pp. 327 - 338
Copyright
Copyright © 1979, The Clay Minerals Society

References

Bischoff, J. L. (1972) A ferroan nontronite from the Red Sea geothermal system: Clays & Clay Minerals 20, 217–223.CrossRefGoogle Scholar
Bowen, L. H., Weed, S. B., and Stevens, J. G. (1968) Mössbauer study of micas and their potassium-depleted products: Amer. Mineral. 54, 72–84.Google Scholar
Dolcater, D. L., Syers, J. K., and Jackson, M. L. (1970) Titanium as free oxide and substituted forms in kaolinites and other soil minerals: Clays & Clay Minerals 18, 71–79.CrossRefGoogle Scholar
Dunoyer de Segonzac, G. (1965) Les argiles du Crétace supérieur dans le basin de Douala (Cameroun): Problèmes de diagenèse: Bull. Serv. Carte Geol. Alsace Lorraine 17, 287–310.CrossRefGoogle Scholar
Foscolas, A. E. and Kodama, H. (1974) Diagenesis of clay minerals from Lower Cretaceous shales of North Eastern British Columbia: Clays & Clay Minerals 22, 319–336.CrossRefGoogle Scholar
Goodman, B. A., Russell, J. D., Fraser, A. R., and Woodhams, F. W. D. (1976) A Mössbauer and i.r. spectroscopic study of the structure of nontronite: Clays & Clay Minerals 24, 52–59.CrossRefGoogle Scholar
Hoffman, J. and Hower, J. (1979) Clay mineral assemblages as low grade metamorphic geothermometers: application to the thrust faulted Disturbed Belt of Montana, U.S.A.: Soc. Econ. Paleontol. Mineral. Spec. Publ. No. 26, 55–79.Google Scholar
Hoffman, J., Hower, J., and Aronson, J. (1976) Radiometric dating of time of thrusting in the Disturbed Belt of Montana: Geology 4, 16–20.2.0.CO;2>CrossRefGoogle Scholar
Hower, J., Eslinger, E., Hower, M., and Perry, E. (1976) The mechanism of burial diagenetic reactions in argillaceous sediments, 1. Mineralogical and chemical evidence: Geol. Soc. Amer. Bull. 87, 725–737.2.0.CO;2>CrossRefGoogle Scholar
Hower, J. and Mowatt, T. C. (1966) The mineralogy of illites and mixed-layer illite/montmorillonites: Amer. Mineral. 51, 825–854.Google Scholar
Jackson, M. L. (1956) Soil Chemical Analysis—Advanced Course: University of Wisconsin, College of Agriculture, Dep. of Soils, Madison, Wisconsin, 894 pp.Google Scholar
Malathi, N., Puri, S. P., and Saraswat, I. P. (1969) Mössbauer studies of iron in illite and montmorillonites: J. Phys. Soc. Jpn. 26, 680–683.CrossRefGoogle Scholar
Medlin, J. H., Suhr, N. N., and Bodkin, J. B. (1969) Atomic absorption analysis of silicates employing LiBO2 fusion: At. Absorpt. Newsl. 8, 25–29.Google Scholar
Mudge, M. R. (1970) Origin of the Disturbed Belt in northwestern Montana: Geol. Soc. Amer. Bull. 81, 377–392.CrossRefGoogle Scholar
Mudge, M. R. (1972a) Prequaternary rocks in the Sun River Canyon area, northwestern Montana: U.S. Geol. Surv. Prof. Pap. 663–A, 142 pp.Google Scholar
Mudge, M. R. (1972b) Structural geology of the Sun River Canyon and adjacent areas, northwestern Montana: U.S. Geol. Surv. Prof. Pap. 663–B, 51 pp.Google Scholar
Muffler, L. J. and White, D. E. (1969) Active metamorphism of upper Cenozoic sediments in the Salton Sea geothermal field and the Salton Trough, Southwestern California: Geol. Soc. Amer. Bull. 80, 157–182.CrossRefGoogle Scholar
Osthaus, B. B. (1954) Chemical determination of tetrahedral ions in nontronites and montmorillonites: Clays & Clay Minerals, Proc. 2nd Nat. Conf., Nat. Acad. Sci.-Nat. Research Council Publ. 327, 407–416.Google Scholar
Oxburgh, E. R. and Turcotte, D. L. (1974) Thermal gradients and regional metamorphism in overthrust terrains with special reference to the eastern Alps: Schweiz. Mineral. Petrogr. Mitt. 54, 641–662.Google Scholar
Perry, E. and Hower, J. (1970) Burial diagenesis in Gulf Coast pelitic sediments: Clays & Clay Minerals 18, 165–177.CrossRefGoogle Scholar
Reynolds, R. C. Jr. and Hower, J. (1970) The nature of interlaying in mixed-layer illite-montmorillonites: Clays & Clay Minerals 18, 25–36.CrossRefGoogle Scholar
Rozenson, I. and Heller-Kallai, L. (1976a) Reduction and oxidation of Fe3+ in dioctahedral smectites: 1. Reduction with hydrazine and dithionite: Clays & Clay Minerals 24, 271–282.CrossRefGoogle Scholar
Rozenson, I. and Heller-Kallai, L. (1976b) Reduction and oxidation of Fe3+ in dioctahedral smectites: 2. Reduction with sodium sulfide solutions: Clays & Clay Minerals 24, 283–288.CrossRefGoogle Scholar
Rozenson, I. and Heller-Kallai, L. (1976c) Mössbauer spectra of dioctahedral smectites: Clays & Clay Minerals 25, 94–101.CrossRefGoogle Scholar
Rozenson, I. and Heller-Kallai, L. (1978) Reduction and oxidation of Fe3+ in dioctahedral smectites: 3. Oxidation of octahedral iron in montmorillonites: Clays & Clay Minerals 26, 88–92.CrossRefGoogle Scholar
Shaw, D. M. (1956). Geochemistry of pelitic rocks. Part III. Major elements and general geochemistry: Geol. Soc. Amer. Bull. 67, 919–934.CrossRefGoogle Scholar
Taylor, G. L., Ruotsala, A. P., and Keeling, R. O. Jr. (1968) Analysis of iron in layer silicates by Mössbauer spectroscopy: Clays & Clay Minerals 16, 381–391.CrossRefGoogle Scholar
Weaver, C. E. (1960) Possible uses of clay minerals in the search for oil: Amer. Assoc. Petrol. Geol. Bull. 44, 1505–1518.Google Scholar
Weaver, C. E. and Beck, K. C. (1971) Claywater diagenesis during burial: How mud becomes gneiss: Geol. Soc. Amer. Spec. Pap. 134, 96 pp.Google Scholar
Weaver, C. E. and Pollard, L. D. (1973) The Chemistry of Clay Minerals: Elsevier-Holland, New York, 213 pp.Google Scholar
Weaver, C. E., Wampler, J. M., and Pecuil, T. E. (1967) Mössbauer analysis of iron in clay minerals: Science 156, 504–508.CrossRefGoogle ScholarPubMed