Mineralogy of the non-carbonate material from the Chalk of Berkshire and Oxfordshire, England

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Abstract
This paper presents detailed mineralogical analyses of the non-carbonate material obtained from four cored boreholes in the Chalk of Berkshire and Oxfordshire, England. Consideration is given to the relationship between the non-carbonate material and the interstitial water chemistry.Sample preparation was by means of acid digestion followed by vacuum sedimentation. Analyses were carried out using X-ray diffraction techniques.Results are presented in a semi-quantitative form based upon integrated peak intensities and are compared to those of previous studies on the Chalk of southern England. It is concluded that the zones of occurrence of the major clay minerals as demonstrated in this study are in general agreement with those established by other authors. The non-carbonate content of the Chalk increases from the concealed beds at the Fair Cross site towards the outcrop Chalk of Lambourn and Harwell. The variation in mineralogy and purity is ascribed to changing conditions of deposition and to diagenesis related to groundwater circulation.