Introduction and overview

This volume grew out of the various oral and poster presentations given during the ‘Evaporite’ session at the International Geological Union conference (2004) in Florence, Italy. It was clear that only a few of the participants or attendees, coming from many countries and various distant parts of the world, were well informed about evaporites outside their immediate area of study, apart from data from the most commonly available literature. Diversity in the languages of publication and the logistical difficulty of making first-hand comparisons acts as a major barrier to study. As a result, the basic concept of evaporites that most geologists have is that deposits are the product of simple, chemically controlled environments and, if evaporitic compounds are chemically the same, then it follows that their lithology and origin are also the same. Based on many studies over the past 30 years, it is now clear that this long-held impression is manifestly untrue. The disparities were very evident in the photographic presentations and descriptions at the 2004 International Geological Congress: the same evaporitic compounds can have distinct and diverse lithology, depositional sources and geological history. They cannot be considered to arise solely from simple, direct chemical origins as explained by a single universal model! This is the same paradigm of sedimentation that functions with other deposits, such as siliciclastics and carbonates, and should also apply to evaporites. In putting this volume together, we realized there were many questions about evaporites from parts of the world not discussed in Florence, despite the large number of participants. Thus, in order to broaden and balance the topics already in our Congress program, we added two additional review papers. One paper that we have added is a chapter covering the many evaporites in the former Soviet Union territory: Russia, Ukraine, Belarus and Moldova. This area contains many deposits of different ages but is poorly represented in Western literature due to language barriers. This review paper gives those scientists who do not read languages written in the Cyrillic alphabet an opportunity to become acquainted with those evaporites. The second additional paper is also a review, taken from tectonically stable interior basins of North America (the Permian deposits of Texas and New Mexico). This study is in contrast to many other deposits described in this volume as it contains a well-developed, undisturbed basin-fill. As a group, this set of 18 papers gives a good introduction to many diverse environments and styles of deposition and preservation to be found in varied evaporite basins. In order to make the volume more approachable, we divided the book into five parts: (1) Tectonics, Basin Evolution and Evaporites, (2) Working depositional Models, (3) Post-depositional Evolution of Sediments, (4) Ancient Basins, and (5) Regional Reviews. The first section (five papers) places the formation of evaporite basins and the mechanical behaviour of some evaporites into an observed structural/stratigraphic framework. Karner & Gamboa present the creation and early infilling of the South Atlantic rift basin, while Bertoni & Cartwright address the destabilization and massive reworking of evaporitic sediments into an adjacent ocean basin. Specific tectonic settings with associated depositional styles and stratigraphy are presented in the other three papers in part one, and links tectonics to sedimentary styles. The early and middle Miocene evaporites of Iraq, by Ismail Al-Juboury, Mehdi AlTarif & Al-Eisa, and Iran by Rahimpour-Bonab, Shariatinia & Siemann are strongly tied to their rapid geologic evolution. Turner & Sherif, describe a large Triassic–Jurassic basin that stretches across North Africa from Libya to Morocco and its evolution. The second part of the book (two papers) presents a fairly rigorous treatment of evaporitic water-body behaviour with associated sedimentation. The first paper, by Bąbel, is based on the observed sedimentary section from the middle Miocene of the Carpathian foredeep, and addresses the problem of how evaporite deposition is controlled by water stratification, circulation and mixing. The second paper, by Lopez & Mandado, deals with an observed