Introduction and Overview

Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021 Introduction and overview B. C. SCHREIBER1,M.BA˛BEL2 & S. LUGLI3 1University of Washington, USA (e-mail: [email protected]) 2Institute of Geology, Warsaw University, Al. Zwirki i Wigury 93, PL-02-089 Warszawa, Poland 3Dipartimento di Scienze Della Terra, Universita` degli Studi di Modena e Reggio Emilia, Largo S. Eufemia 19, 41100 Modena, Italy This volume grew out of the various oral and poster an opportunity to become acquainted with those presentations given during the ‘Evaporite’ session evaporites. The second additional paper is also a at the International Geological Union conference review, taken from tectonically stable interior (2004) in Florence, Italy. It was clear that only a basins of North America (the Permian deposits of few of the participants or attendees, coming from Texas and New Mexico). This study is in contrast many countries and various distant parts of the to many other deposits described in this volume as world, were well informed about evaporites it contains a well-developed, undisturbed basin-fill. outside their immediate area of study, apart from As a group, this set of 18 papers gives a good intro- data from the most commonly available literature. duction to many diverse environments and styles of Diversity in the languages of publication and the deposition and preservation to be found in varied logistical difficulty of making first-hand compari- evaporite basins. sons acts as a major barrier to study. As a result, In order to make the volume more approachable, the basic concept of evaporites that most geologists we divided the book into five parts: (1) Tectonics, have is that deposits are the product of simple, Basin Evolution and Evaporites, (2) Working deposi- chemically controlled environments and, if evapori- tional Models, (3) Post-depositional Evolution of tic compounds are chemically the same, then it Sediments, (4) Ancient Basins, and (5) Regional follows that their lithology and origin are also the Reviews. The first section (five papers) places the same. Based on many studies over the past 30 formation of evaporite basins and the mechanical years, it is now clear that this long-held impression behaviour of some evaporites into an observed struc- is manifestly untrue. The disparities were very tural/stratigraphic framework. Karner & Gamboa evident in the photographic presentations and present the creation and early infilling of the South descriptions at the 2004 International Geological Atlantic rift basin, while Bertoni & Cartwright Congress: the same evaporitic compounds can address the destabilization and massive reworking have distinct and diverse lithology, depositional of evaporitic sediments into an adjacent ocean sources and geological history. They cannot be con- basin. Specific tectonic settings with associated sidered to arise solely from simple, direct chemical depositional styles and stratigraphy are presented in origins as explained by a single universal model! the other three papers in part one, and links tectonics This is the same paradigm of sedimentation that to sedimentary styles. The early and middle Miocene functions with other deposits, such as siliciclastics evaporites of Iraq, by Ismail Al-Juboury, Mehdi Al- and carbonates, and should also apply to evaporites. Tarif & Al-Eisa, and Iran by Rahimpour-Bonab, In putting this volume together, we realized Shariatinia & Siemann are strongly tied to their there were many questions about evaporites from rapid geologic evolution. Turner & Sherif, describe parts of the world not discussed in Florence, a large Triassic–Jurassic basin that stretches across despite the large number of participants. Thus, in North Africa from Libya to Morocco and its order to broaden and balance the topics already in evolution. our Congress program, we added two additional The second part of the book (two papers) presents review papers. One paper that we have added is a a fairly rigorous treatment of evaporitic water-body chapter covering the many evaporites in the behaviour with associated sedimentation. The first former Soviet Union territory: Russia, Ukraine, paper, by Ba˛bel, is based on the observed sedimen- Belarus and Moldova. This area contains many tary section from the middle Miocene of the deposits of different ages but is poorly represented Carpathian foredeep, and addresses the problem of in Western literature due to language barriers. how evaporite deposition is controlled by water This review paper gives those scientists who do stratification, circulation and mixing. The second not read languages written in the Cyrillic alphabet paper, by Lopez & Mandado, deals with an observed From:SCHREIBER, B. C., LUGLI,S.&BA˛BEL, M. (eds) Evaporites Through Space and Time. Geological Society, London, Special Publications, 285, 1–13. DOI: 10.1144/SP285.1 0305-8719/07/$15.00 # The Geological Society of London 2007. Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021 2 B. C. SCHREIBER ET AL. example of modern evolution of water in several An overview of evaporite puzzles saline lakes from north-central Spain. Part three contains only two papers both of Elucidating the geological history of evaporites is which deal with unusual aspects of synsedimentary never straight-forward because evaporite deposits deformation and then diagenesis within two very record information in many different ways. Some different basins. The first is a study by Alberto, of the most difficult problems encountered by geol- Carraro, Giardino & Tiranti that addressess an ogists studying evaporities include realistic assess- unusual form of gypsum diagenesis present within ments of the time intervals of evaporite formation some tectonized Triassic evaporites that rsults in a and accumulation, the necessary climatic controls, much altered facies (rauhwacke or ‘pseudo- and the rates of water evaporation/ionic concen- carnioles’) developed within the original evaporite tration required for evaporite formation. These con- rocks. These truly reveal the complexity caused by straints are presented below, followed by a review both the tectonics and burial/exhumational history of the styles of sedimentation imposed on evaporite of the deposits. The second paper in this section, formation by differing synsedimentary tectonic by Lugli, Dominici, Barone, Costa & Cavozzi, is a histories within the formative basins. It seems that geochemical study of the late Miocene (Messinian) tectonically active and passive basins develop Apennine gypsum deposits that considers their significantly different facies assemblages, as with deposition in basins which are initially marine- other types of deposits. sourced but change over to a largely nonmarine (but concentrated) evolution higher in the strati- Depositional time intervals in evaporite graphic section. This observation appears to be formation valid throughout the late Miocene (Messinian) in many areas of the Mediterranean and may well A feature most evaporites share is that the total hold true in other evaporite sequences. depositional time-period for formation and accumu- The fourth and largest section of the book (seven lation is very short (even in very thick deposits), so papers), presents a series of observation of diverse short that the entire deposit may be represented by evaporites ranging in age from the late Miocene to only one or two biozones in the surrounding area. the Neoarchean. The first, another paper on the late This means that standard biostratigraphical Miocene of Italy by Lugli, Bassetti, Manzi, methods cannot date the evaporite formations pre- Barbieri, Longinelli & Roveri, discusses isotopic cisely and some other high-resolution methods are composition and organic matter in the evaporites of more useful. For example, Anderson et al. (1972), the Northern Apennines. Late Miocene geology and Richter-Bernburg (1963) and Kirkland (2003), stratigraphy of the Southern Apennines is addressed based on isochronous correlation of particular by Matano. Next presented are the middle Miocene sequences of varves in laminated evaporites, esti- gypsum evaporites of the Carpathian region mated that the late Permian evaporites of both addressed first by Ba˛bel & Boguckiand then by West Texas and the European Zechstein represent Bukowski, Czapowski & Karoli. The isotopic com- deposition over a period of only c. 275,000– position of the K–Mg sulphates of the same age in 300,000 years. Based on the detailed magnetostrati- one of the Carpathian basins is addressed Hryniv, graphic study by Krijgsman et al. (1999), we also Parafiniuk & Peryt. The next topic treats the origins know that the late Miocene (Messinian) of the of some of the Upper Permian (Zechstein) salts of Mediterranean took no more than 600,000 years, SW Poland as discussed by Vovnyuk & Czapowski. and sections of it (0.75–2 km thick) probably took The last paper in this section, by Gandin & Wright, far less time. In many other evaporite basins it is examines deposits from the Neoarchean and much more difficult to estimate the total time inter- addresses the elusive products of extreme evaporite val precisely due to the lack of significant stratigra- diagenesis, where only morphological remnants of phical markers (like ash beds) and, consequently, evaporites are left. applicable methodology. It seems that the internal Finally, in part five of this volume, there are the stratigraphy of evaporite formations with well- two regional review papers, describing two amaz- preserved primary features

Load more