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Glauconitization of detrital silica substrates in the Barton Formation (upper Eocene) of the Hampshire Basin, southern England
Article first published online: 14 JUN 2006
Volume 34, Issue 5, pages 825–835, October 1987
How to Cite
HUGHES, A. D. and WHITEHEAD, D. (1987), Glauconitization of detrital silica substrates in the Barton Formation (upper Eocene) of the Hampshire Basin, southern England. Sedimentology, 34: 825–835. doi: 10.1111/j.1365-3091.1987.tb00806.x
- Issue published online: 14 JUN 2006
- Article first published online: 14 JUN 2006
- (Manuscript received 30 January 1986; revision received I2 January 1987)
Upper Eocene detrital silica grains (chert and quartz) of the Hampshire Basin display alteration and replacement fabrics by glauconite. Silica grains have etched surfaces due to glauconitization which appear green in reflected light and thin section.
Quartz grains were glauconitized by surface nucleation and replacement, which spreads from the margin with progressive glauconitization, replacing the quartz grain interior. Chert grains were glauconitized by surface replacement and nucleation internally along cracks and in pores. Different forms of glauconite are associated with the two minerals; glauconite associated with quartz is generally highly-evolved whereas glauconite associated with chert is of the evolved variety. This is interpreted as being due to different surface-reaction control mechanisms associated with the two forms of silica. There is no evidence to suggest that glauconite evolved in stages from a nascent form.
Two crystalline morphological forms of glauconite are found associated with both quartz and chert. Glauconite growing within a confined space has a laminated morphology whilst glauconite occurring on the surface has a rosette morphology.