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1 B r i n e s a n d E v a p o r i t e s

2 Short Course in Geology: Volume 3 Brines and Evaporites Peter Sonnenfeld and J.-P. Perthuisot 'SQ Short Course Presented athe 28th International Geological Congress Washington, D. C. American Geophysical Union, Washington, D.C.

3 Maria Luisa Crawford and Elaine Padovani Short Course Serie Editor Library of Congress Cataloging-in-Publication Data Sonnenfeld, Peter. Brines and evaporites. Bibliography: p. 1. Salt. 2. Evaporites. II. Title. QE S2S ISBN I. Perhuisot, J.-P. 552' Copyright 1989 by the American Geophysical Union, 2000 Florida Avenue, NW, Washington, DC 20009, U.S.A. Figures, tables, and short excerpts may be reprinted in scientific books and journals if the source is properly cited. Authorization to photocopy items for internal or personal use, or the internal or personal use of specific clients, is granted by the American Geophysical Union for libraries and other users registered with the Copyright Clearance Center (CCC) Transactional Reporting Service, provided that the base fee of $1.00 per copy plus $0.10 per page is paid directly to CCC, 21 Congress Street, Salem, MA /89/$ This consent does not extend to other kinds of copying, such as copying for creating new collective works or for resale. The reproduction of multiple copies and the use of full articles or the use of extracts, including figures and tables, for commercial purposes requires permission from AGU. Printed in the United States of America.

4 CONTENTS Part L Genesis of Evaporites P. Sonnenfeld Preface 3 Introduction 5 Climatological factors 5 Freeze-drying 6 Evaporation 6 Aridity 6 Air masses 8 Hydrography 9 The Coriolis effect 10 The entrance restriction 11 Brines 11 Density stratification 13 Radiation and thermal effects 14 Anions in the concentrating brine 15 Cation surplus in the brine 16 Complexing in the brine 17 Biota in hypersaline brines 17 Brines moving through evaporites 18 Evaporitic rocks 19 Non-marine evaporites 20 Groundwater precipitation 20 The polar environment 22 Subtropicalakes 23 Sebkhas 25 Marine evaporites 25 Evaporite-related marine carbonates 26 Marine gypsum 27 Celestite and barite 27 Marine halite 27 Marine potash salts 28 Marine magnesium salts 34 Substitutions 34 Accessories in marine evaporites 35 Siliciclastics 36 Base metals around evaporites 39 Organic matter in evaporites 40 Secondary alteration of marine evaporites Dehydration of gypsum 41 Sulfatization of potash beds 43 Further alterations 46 Basin configuration 46 Basin modelling 51 The bull's eye model 51 The tear-drop model 53 The open shelf model 53 The barred basin model 54 The reflux model 55 The deep basin model 55 The deep dry basin or giant flood model The synsedimentary subsidence model Conclusion 64 Acknowledgments iii

5 iv CONTENTS Part IL Recent Evaporites J P. Perthuisot 65 Preface 67 Abstract 69 Introduction 69 Main characteristics of modern evaporite basins 69 Conditions of evaporite formation 69 Tentative typology of present sites of evaporites 70 Salt precipitation 71 Salinity distribution and gradients 72 Rate of deposition of evaporites 72 The significance of water depth 73 Independence of evaporitic processes of depth of water 73 Consequences of a deep water body 73 Organic matter and evaporites 74 The origin of organic matter in paralic evaporite basins 74 Preservation of organic matter 75 Modern evaporite occurrences 80 Continental evaporitic areas 80 Groundwater precipitation: The pedological crusts 80 Intermittent lakes 80 Perennial lakes 85 Paralic evaporitic areas 92 Hydrophysical and hydrochemical arrangement of paralic areas Experimental models: Salinas 94 The evaporitic tidal flats 98 The role of evaporitic tidal flats (sebkhas) and their feeder lagoons Sporadically flooded basins 101 Evaporitic inlets 103 Paralic to deep basins with continuous seawater input 105 The necessity of a dynamic approach to evaporite deposits 116 Conclusion 116 Acknowledgments 118 Index of evaporitic minerals 119 References cited

6 LIST OF FIGURES 1. Relative humidity over saturated brines 2. Width of subtropical anticyclones 3. The Coriolis effect on inflow/outflow interfaces 4. Crusts in semi-arid soils 5. Primary precipitation curve 6. Precipitation paths in exposed and covered brines 7. ph of iron sulfide stability 8. Primary sylvite-carnallite relationship 9. Modes of alkane production 10. Gypsum and celestite solubility in NaCl-brines 11. Basin with limited subsidence 12. Areal extent of Permian Castile and Salado seas 13. The bull's eye pattern 14. The Kara Bogaz Gol 15. The Salina A-1 unit in the Michigan Basin 16. The tear-drop pattern 17. The open shelf model 18. The barred basin model 19. The reflux model 20. The deep basin model 21. Wilfarth's deep dry basin model 22. Upper Miocene halite distribution under the Mediterranean Sea 23. The synsedimentary subsidence model 24. Stages in the synsedimentary subsidence model 25. Organic matter production in terrestrial, paralic and marine settings 26. Paralic species distribution and quantitative variations of biota 27. Source rock potential of the proximal paralic area in a lagoon 28. Bathymetric map and water currents in Lake Melah (Algeria) 29. Content of organic matter in present Lake Melah sediments 30. Organic matter in present sediments of Bahirat el Biban 31. The sedimentological framework of the paralic setting 32. Comparison of brines in continental sebkha and paralic salt basin 33. The Sebkha Kourzia (Tunisia) 34. Composition of Sebkha Kourzia brines 35. Tentative reconstruction of the evolution of the Sebkha Kourzia basin 36. Setting and drainage area of the Dead Sea 37. Bathymetry of the Dead Sea 38. Temperature, density and salinity in the northern basin of the Dead Sea 39. Recent evolution of Dead Sea brines (northern basin) 40. The Kara Bogaz Gol 41. Lake Chad 42. The lakes of the Kanem Peninsula 43. Lake Liwa 44. Composition of the surficial evaporite crust in Lake Liwa 45. Salinity gradients in the paralic setting 46. Climatic conditions at Salin de Giraud 47. Brine movements in concentrators at Salin de Giraud 48. Brine densities in the Salin de Giraud salt works 49. Present sediments in the Salin de Giraud salt works 50. Plant associations in the Salin de Giraud salt works 51. Trucial Coast sebkha 52. Schematic section of Trucial Coast tidal sebkhas 53. Laguna Ojo de Liebre, Baja California, Mexico 54. Location and bathymetric map of Bahirat el Biban and Sebkha bou Jmel 55. Evolution of the ionic composition of brines in Sebkha bou Jmel

7 vi FIGURES AND TABLES 56. Map of the Mg/Ca ionic ratio of surficial waters in Bahirat el Biban 57. Total organicarbon content of surficial waters in Bahirat el Biban 58. Boccana de Virrila (Peru) 59. Khwar al Odeid (Qatar) 60. The salinity field at Khawr al Odeid 61. Lake Assal 62. The Sebkha el Melah 63. Geological map of the Sehkha el Melah and its surrounding area 64. Isobathic map of sedimentary infill in the Sebkha el Melah 65. Isobathic map of the Flandrian sequence in the Sebkha el Melah 66. Isopach map of the sulfate layer, Sebkha el Melah 67. Isopach map of the halite layer, Sebkha el Melah 68. Cross section of the sedimentary infill of the Sebkha el Melah 69. Block diagram of Sebkha el Melah 70. Development of Flandrian sedimentation in the Sebkha el Melah 71. Explanation of the "bull's eye" pattern of a paralic evaporitic basin 72. Size comparison between a present and an Upper Jurassic evaporite basin 73. Zones of restriction in the Triangulo de las Bermudas, Spain 74. Zones of restriction in the Baltic Sea LIST OF TABLES 1. Changing ion ratios in precipitating brines 2. Types of perennial water bodies 3. Data on Sebkah el Melah 3O 7O 115

Basement Geology of the Beardmore Glacier Region. Triassic Vertebrates in the Transantarctic Mountains

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