The mineralogy and surface area of till samples from Buckinghamshire, Lancashire and Norfolk
Kemp, S.J.; Wagner, D.; Mounteney, I.. 2009 The mineralogy and surface area of till samples from Buckinghamshire, Lancashire and Norfolk. Nottingham, UK, British Geological Survey, 60pp. (IR/08/053) (Unpublished)Before downloading, please read NORA policies.
This report describes the results of mineralogical and surface area analysis completed on the ‘fine matrix’ (<425 μm material) of a suite of tills from England. The work was carried out as part of the ongoing BGS project, ‘Physical Properties and behaviour of UK rocks and soils’ under the Land Use and Development Science Theme. The first part of the report gives a summary of previous BGS mineralogical studies of till deposits. A summary of analytical methods employed (X-ray diffraction analysis and surface area determinations) is then provided and the results discussed with reference to their likely effect on the engineering performance. Analyses indicate that the till samples are ‘fine matrix’-rich and typically composed of location-dependant varying proportions of quartz, calcite and phyllosilicates/clay minerals together with a range of minor-trace constituents. Given their typically ‘fine-matrix’-dominated nature, the geotechnical behaviour of the till samples examined is likely to be influenced by both the proportion of phyllosilicates/clay minerals present and their composition and can be indicated by the surface area measurements. This being the case, the tills from Thetford (BHs 2 and 5) and Milton Keynes would be expected to show the most problematic engineering behaviour. Although the mineralogy of till deposits are typically thought to be derived from several sources, mineral and clay mineral assemblages suggest that the tills in this study are predominantly derived from underlying lithologies. Tills from various locations in Norfolk other than Thetford appear to be principally derived from the Norwich and Red Crag formations with some input from the Upper Chalk whilst the more carbonate-rich Thetford tills appear to have a greater Upper Chalk input. The mineralogically distinct Lancashire tills suggest Permo-Triassic sources, probably the Mercia Mudstone Group while the Milton Keynes tills indicate that the underlying Jurassic limestones and mudstones probably produced their sediment supply.
|Item Type:||Report (UNSPECIFIED)|
|Programmes:||BGS Programmes 2008 > Land use and development|
|Additional Information:||This report was made open by author 20.09.12. This item has been internally reviewed but not externally peer-reviewed|
|Date made live:||20 Sep 2012 13:29|
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