Porosity reduction, microfabric and resultant lithification in UK uncemented sands

Abstract
Summary: Studies of the extent of diagenetic change in matrix-free, uncemented, quartzose sands ranging in age from the Jurassic to the Recent in the UK have been carried out as part of a geotechnical research programme. All the sands studied are thought to have experienced only a relatively small depth of burial and the extent of diagenetic change is consequently small. Previous studies of the in situ fabric of sands in this category have been limited owing to the sampling difficulties created by their very friable nature. Careful sampling, however, has succeeded in obtaining undisturbed material and has facilitated studies of the porosity, microfabric and degree of lithification. Distinctive changes, progressive with age, include reduction of porosity, an increase in the numbers and complexity of grain contacts and an increasing degree of lithification. The cause of these diagenetic changes are discussed and it is concluded that the evidence strongly favours pressure solution of the detrital quartz grains as the dominant process.