Abstract
This edited volume of papers has been assembled as a tribute to the research of Douglas James Shearman, whose name is synonymous with the study of modern evaporite-dominated environments. The chapters have been selected from papers presented at two research meetings that were held in Abu Dhabi in 2004 and 2006. They provide an excellent overview of the nature of modern carbonate-evaporite environments, mainly in the Arabian Gulf region, where Shearman conducted a huge amount of research from the early 1960s onwards. In addition, the volume contains contributions on various aspects of sabkha sediment geochemistry and their relevance to the rock record (where they are of key interest in the context of hydrocarbon reservoir development). Indeed, the book is structured so that it groups the contributions around these three theme areas. The contributions in this book thus span across the research interests of both geomorphologists and geologists, but for the readers of The Holocene it is likely that the first set of contributions (comprising some nine chapters) will be of most interest, as these deal with aspects of sabkha geomorphology and contemporary sedimentology, and with the role of sea-level and environmental change on their development.
The book opens with a short but fascinating insight into the life and research of Douglas Shearman and a brief review of the regional and scientific context for the book. This is followed by a very informative chapter by Graham Evans on the geological development of the Arabian Gulf, the key contemporary coastal geomorphological environments, and the evolutionary development of the modern sabkha environments. This provides a useful introduction to the rest of the book. The following chapter, by Kendall and Alsharhan, provides a very nicely illustrated overview of the geomorphological and sedimentary environments of the Adu Dhabi region and would provide some fantastic and accessible case study material of the unique character of these environments for undergraduate students. Robert Park then goes on to provide a review of the role of sea-level change in the evolution of the Abu Dhabi sabkhas (again wonderfully illustrated), Ananda Gunatilaka provides an account of the environment history of the region based on stable-isotope analysis, and Eugene Shinn contributes a short, but informative, chapter on contemporary sabkha coastal landform development in Qatar. The next two chapters (the first by Christian Strohmenger et al., the second by Monique Mettraux et al.) consider the development of coastal sabkha sediment facies and describe the different elevationally controlled sabkha zones in, respectively, the Al-Qanatir Island area of Abu Dhabi, and the Barr Al Hikman sabkha of Oman. Both are beautifully illustrated with a mix of both field and thin section imagery showing the depositional character of each zone. The final two chapters of this first section of the book deal with, first, the development of different depositional sediment types and their preservation in different sabkha zones (again by Kendall and Alsharhan), and second the engineering properties of these sabkha sediments (by Roger Epps) which has obvious implications in terms of the urban development of this region.
The second block of contributions deal with, as outlined above, aspects of sabkha geochemistry in the region. This includes several short contributions by Warren Wood on models of sabkha evaporite mineral formation, by Suad Qabazard and co-workers on sabkha sediment geochemistry, by Anthony Kirkham on the evaporite minerals in Abu Dhabi, and by Fabien Kenig on microbial mat development and other organic matter sources within sabkha sediments. This section concludes with a contribution on the role of bacterial sulphate reduction in carbonate diagenesis by David Wright and Anthony Kirkham.
Much of the final section of the book may well be outside the immediate interest of readers of The Holocene, but nonetheless represents an interesting collection of papers on carbonate-evaporite sequences in the rock record. The first of these four papers is a lengthy consideration of evaporite source rocks by John Warren, and specifically the controls on organic-rich laminate sediment accumulation. The following two contributions by Elisabetta Costa et al. and Mohamad Hafid et al. then consider aspects of sabkha sediment tectonics and their deformation, the latter focused on data from the Moroccan Atlantic margin. The final chapter, by Federico Ortí, discusses the development of selenite facies in marine evaporates, including aspects of their crystallography, facies development and sequence evolution. For the many geomorphologists and sedimentologists who take their students to the Sorbas region of SE Spain, this beautifully illustrated chapter would be a useful read.
Overall, this is a very nicely presented volume with some wonderful colour images and very useful process-orientated diagrams. For anyone interested in understanding more about the nature, character and controls on the geomorphology and sedimentology of modern carbonate-evaporite environments this volume is highly recommended.