This book is the long-overdue successor to the 1971 publication The Clay Mineralogy of British Sediments by R. M. S. Perrin, in which several decades of clay mineral research were for the first time collated and discussed within a stratigraphical framework.
The twelve contributors have produced a much more detailed and interpretative account in their ten chapters that are arranged in reverse stratigraphical order. Much use has been made of data from UK hydrocarbon exploration activities that reached their height in the 1980s and 1990s, augmented by academic research studies and government-funded strategic surveys. Most data have been determined using X-ray diffraction (XRD) analyses, underlining the importance of this technique when studying fine-grained minerals, but the book is enhanced by the inclusion of both colour and monochrome optical, scanning electron and transmission electron micrographs.
The first chapter (Huggett & Knox) discusses the smectite-dominated clay mineral assemblages of the onshore Tertiary and their more extensive offshore equivalents which are derived from the alteration of volcanic ash and the weathering of smectite-rich soils. However, considering the increasing level of interest in the shallow interface, it is perhaps disappointing that few data and little discussion are focussed on the Quaternary deposits that often overlie the ‘solid geology’.
Almost half of the book is composed of lengthy chapters on the onshore Cretaceous, Jurassic and Permo-Triassic, contributed by C. V. Jeans. These chapters have a similar style, drawing on much unpublished literature, presenting abundant stacked X-ray diffraction traces and copious appendices of tabulated data. The stratigraphical and regional variations in the clay mineral assemblages are employed to interpret palaeogeography, palaeoclimate, sediment source areas, soil types, volcanism and sedimentary facies.
Offshore chapters for the Cretaceous and Jurassic (Wilkinson, Haszeldine & Fallick), the Permo-Triassic (Ziegler) and the Carboniferous (Shaw) illustrate the use of clay mineral assemblages to hydrocarbon exploration. In the Cretaceous and Jurassic chapters, changes in kaolinite morphology and polytype are related to increased burial while K–Ar dating of authigenic illites may record the timing of oil charge; both being used to calibrate basin history. Additional factors control clay mineralogy in the Permo-Triassic including variations in depositional environment, the chemistry and flow of porewaters, the timing of clay mineral formation and the action of meteoric water.
The diverse clay-bearing sedimentary rocks of the onshore Carboniferous (marine and non-marine shales, turbidites, fire-clays, seat-earths, K-bentonites and tonsteins) are reflected in a diversity of their clay mineral assemblages (Spears). Highly variable clay mineral assemblages are typical of the ORS and Devonian, often illustrating the influence of diagenetic or progressive/retrogressive metamorphic change (Hillier, Wilson & Merriman). In the final chapter, R. J. Merriman describes how clay mineral assemblages of Lower Palaeozoic pelites are related to their contrasting geotectonic settings, principally using the Kübler index of illite ‘crystallinity’ for a dataset comprising over 4500 samples.
The wide applicability of clay mineralogy and its role in interpreting geological processes means that this data-filled book should form an essential reference work for not only clay mineralogists but for petroleum geoscientists, engineering geologists, environmental consultancies, forensic specialists, soil scientists and earth science students. The contributors, but especially the editors, are to be congratulated on bringing this long-term project to such a successful conclusion.
