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The Microstructure of Vermicular Glaucony

Published online by Cambridge University Press:  28 February 2024

Simon G. McMillan
Simon G. McMillan*
Affiliation:
Department of Geology, University of Otago, P.O. Box 56, Dunedin, New Zealand
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Abstract

Vermicular glaucony grains observed by transmission electron microscopy (TEM) show three irregularly alternating zones. Zone A has a high degree of linear orientation, no void space, and relatively defect-free lattice-fringe images. Zone B has an amalgamated bundle texture with a sub-parallel, linear orientation of bundles to each other and to zone A. Zone B has little or no void space, and lattice images appear to be a combination of those typical of zone C with minor amounts of modified zone A forms. Zone C has a randomly oriented, curved, and circular or semicircular bundle texture. In addition, zone C has much void space and curvilinear and linear lattice-fringe images with numerous defects, including edge dislocations. Such morphologic and crystallographic characteristics indicate that zones B and C probably comprise the glauconitic minerals of the vermicular glaucony grains, and that zone A comprises non-glauconitic micaceous minerals of higher structural order. Zone B is sharply demarcated from zone A, but B zone bundle textures merge gradationally to those of zone C. These spatial relationships suggest that zone B forms first on the surface of zone A. Sub-parallel orientation in the B zone could be produced by initial confinement between adjacent A zones. Once constraints change or are removed, the randomly oriented, curved, and semicircular or circular bundles of zone C develop.

Keywords

Transmission electron microscopyVermicular glaucony
Type
Research Article
Information
Clays and Clay Minerals , Volume 42 , Issue 1 , February 1994 , pp. 63 - 70
Copyright
Copyright © 1994, Clay Minerals Society

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References

Amouric, M., and Parron, C., (1985) Structure and growth mechanism of glauconite as seen by high-resolution transmission electron microscopy: Clays & Clay Minerals 33, 473–482.CrossRefGoogle Scholar
Banfield, J. F., and Eggleton, R. A., (1988) Transmission electron microscope study of biotite weathering: Clays & Clay Minerals 36, 47–60.CrossRefGoogle Scholar
Brown, E. H., (1963) The geology of the Mt. Stoker area, Eastern Otago. Part 1. Metamorphic geology: N. Z. J. Geol. Geophys. 6, 847–871.CrossRefGoogle Scholar
Burst, J. F., (1958a) “Glauconite” pellets: Their mineral nature and applications to stratigraphic interpretations: Bull. Am. Assoc. Petrol. Geol. 42, 310–327.Google Scholar
Burst, J. F., (1958b) Mineral heterogeneity in “glauconite” pellets: Amer. Mineral. 43, 481–497.Google Scholar
Carter, R. M., and Norris, R. J., (1976) Cainozoic history of southern New Zealand: An accord between geological observations and plate-tectonic predictions: Earth Planet. Sci. Lett. 31, 85–94.CrossRefGoogle Scholar
Carter, R. M., (1988) Post-breakup stratigraphy (Kaikoura Synthem: Cretaceous-Cenozoic) of the continental margin of southeastern New Zealand: N. Z. J. Geol. Geophys. 31, 405–429.CrossRefGoogle Scholar
Galliher, E. W., (1935) Geology of glauconite: Bull. Am. Assoc. Petrol. Geol. 19, 1569–1601.Google Scholar
Iijima, S., and Buseck, P. R., (1978) Experimental study of disordered mica structures by high resolution electron microscopy: Acta. Cryst. A34, 709–719.CrossRefGoogle Scholar
Ireland, B. J., Curtis, C. D., and Whiteman, J. A., (1983) Compositional variation within some glauconites and illites and implications for their stability and origins: Sedimentology 30, 769–786.CrossRefGoogle Scholar
Lee, J. H., Ahn, J. H., and Peacor, D. R., (1985) Textures in layered silicates: Progressive changes through diagenesis and low-temperature metamorphism: J. Sedim. Petrol. 55, 532–540.Google Scholar
McMillan, S. G., (1993) The Abbotsford Formation: Ph.D. thesis, University of Otago, Dunedin, New Zealand, 646 pp.Google Scholar
Norris, R. J., Carter, R. M., and Turnbull, I. M., (1978) Cainozoic sedimentation in basins adjacent to a major continental transform boundary in southern New Zealand: J. Geol. Soc. Lond. 135, 191–205.CrossRefGoogle Scholar
Odin, G. S., (1972) Observations nouvelles sur la structure de la glauconie en accordeón: Description du processus de genèse par néoformation: Sedimentology 19, 285–294.CrossRefGoogle Scholar
Odin, G. S., 1988 ed. () Green marine clays: Developments in Sedimentology 45, Amsterdam. Elsevier, 445 pp.Google Scholar
Odin, G. S., and Matter, A., (1981) De glauconiarum origine: Sedimentology 28, 611–641.CrossRefGoogle Scholar
Page, R. H., (1980) Partial interlayers in phyllosilicates studied by transmission electron microscopy: Contrib. Mineral. Petrol. 75, 309–314.CrossRefGoogle Scholar
Phakey, P. P., Curtis, C. D., and Oertal, G., (1972) Transmission electron microscopy of fine-grained phyllosilicates in ultra-thin rock sections: Clays & Clay Minerals 20, 193–197.CrossRefGoogle Scholar
Tapper, M., and Fanning, D. S., (1968) Glauconite pellets: Similar X-ray patterns from individual pellets of lobate and vermiform morphology: Clays & Clay Minerals 16, 275–283.CrossRefGoogle Scholar
Vali, H., and Köster, H. M., (1986) Expanding behaviour, structural disorder, regular and random irregular interstratification of 2: 1 layer silicates studied by high resolution images of transmission electron microscopy: Clay Miner. 21, 827–859.CrossRefGoogle Scholar
Wood, B. L., (1968) Otago Schist: in Geological Map of the Dunedin District. 1: 50,000, Benson, W. N., ed., New Zealand Geological Survey Miscellaneous Series Map 1, Department of Scientific and Industrial Research, Wellington, New Zealand.Google Scholar