Sulfidic Sediments and Sedimentary Rocks

David Rickard

• Publisher: Elsevier
• Year: 2012
• ISBN:
  9780080931838
• Topic: Physical Sciences
• Subtopic: Geology & Earth Sciences

This book deals with sedimentary sulfides which are the most abundant authigenic minerals in sediments. Special emphasis is given to the biogeochemistry that plays such a central role in the formation of sedimentary sulfides. It will be of interest to scientists in a number of disciplines, including geology, microbiology, chemistry and environmental science. The sulfur system is important to environmental scientists considering the present and future effects of pollution and anoxia. The development of the sulfur system – particularly the characteristics of ocean anoxia over the last 200 Ma – is useful in predicting the future fate of the Earth surface system as well as in understanding the past. The biochemistry and microbiology of the sulfur system are key to understanding microbial ecology and the evolution of life.

• First monograph on sedimentary sulfides, covering the ancient and modern sedimentary sulfide systems
• Comprehensive, integrating chemistry, microbiology, geology and environmental science
• All key references are included and discussed

Chapter 1

Introduction

David Rickard

Abstract

The study of sedimentary sulfides is one of the most exciting areas of current international research in many areas. Much of the information we have about the nature of the Early Earth environment is based on analyses of sulfides in sedimentary rocks. These studies are also key to understanding the occurrence of global oceanic anoxia and pollution in marine and freshwater systems. The sulfide is produced by microorganisms and thus research into sedimentary sulfides illuminates biological evolution on Earth and the origins of microbial ecology. The sequestration of sulfur in sediments in concert with the consequent preservation of organic carbon means that understanding sedimentary sulfides is a cornerstone of investigations of the global biogeochemical cycles of oxygen and carbon. Molecular approaches to microbial sulfur ecology provide insights into the present sedimentary biome. Sulfide studies have a long history and have contributed to the development of fundamental chemical paradigms such as the law of definite proportions, X-ray structural analyses of solids and, more recently, nanochemistry and nucleation theory.

Keywords

sediments; sulfide; iron; sulfur microbiology; iron microbiology; sulfur chemistry; iron chemistry; geology; history of science; sulfur isotopes; iron isotopes

But facts are chiels that winna ding, And downa be disputed.

Robert Burns, 1786. A Dream

1 Scope and Aims

This book reviews the geochemistry and biogeochemistry of sulfides in sediments and sedimentary rocks and considers the evolution of the sedimentary sulfur cycle and the associated biology through time. Chemical sediments, such as evaporites and hydrothermal precipitates, are not considered. Shales are the most abundant sedimentary rock type and often contain substantial mineral deposits. Therefore, the subject matter of this volume will find application to economic geology. However, mineral deposits per se are outside the remit of this book since enhanced metal contents in shales are often hydrothermally enhanced and not a result of normal sedimentary processes (Chapter 15).

The volume is a synthesis of, especially, the chemistry, biology and geology of sedimentary sulfides. The book structure reflects this multidisciplinary approach. It consists of three basic parts. The chemistry of sulfur and iron in sedimentary sulfides is considered in Chapters 2–7. The biology of sedimentary sulfides, particularly the microbiology and microbial ecology, is described in Chapters 8–10. Chapters 14–17 consider the geology of sedimentary sulfides including both the evolution of the sulfur biome and the sedimentary sulfur cycle through geologic time. The biogeochemistry of stable isotopes of sedimentary sulfides constitutes a link between the biological and geological sections and is considered in Chapters 11 and 12.

The volume is basically aimed at presenting the state of the art of sedimentary sulfide research. As well as introducing the diverse aspects of modern sedimentary sulfide studies, it constitutes a vehicle for information gathering. As such, it is a source book for instructors, students, research scientists, government agencies (especially those involved in program support and management and in environmental assessment and control), private industries concerned with Earth resources and independent consultants. Each chapter represents a research review paper. I have tried wherever possible to cite the source papers and not rely on metadata.

Defining the level of background knowledge of the target audience required to reach research level in relevant aspects of the three major disciplines of chemistry, biology and geology proved a problem. Finally, I decided on an approach that provided sufficient information for a nonspecialist in any one area to understand the other two. At the same time, the specialist might appreciate the explanations of particular aspects of their science including some introduction into the basics of chemistry (e.g. Chapter 2), microbiology (e.g. Chapters 8 and 10), and geology (e.g. Chapters 16 and 17) as relevant to sedimentary sulfide research.

The study of sedimentary sulfides has proven to be one of the most exciting areas of contemporary Earth and environmental science research. Consequently, it has attracted a number of recent reviews (cf. Barton and Hamilton, 2007; Bottrell and Newton, 2004; Brocks and Banfield, 2009; Buick, 2008; Canfield, 2004, 2005; Canfield et al., 2005, 2006; De Beer and Stodley, 2006; DeLong, 2009; Farquhar et al., 2010; Frigaard and Dahl, 2009; Fry et al., 2008; Holland, 2006; Jenkyns, 2010; Jørgensen and Boetius, 2007; Keeling et al., 2010; Kemp et al., 2009; Kirschvink and Kopp, 2008; Luther and Rickard, 2005; Lyons and Gill, 2010; Lyons and Reinhard, 2009; Lyons and Severmann, 2006; Medini et al., 2005; Meyer and Kump, 2008; Montero-Serrano et al., 2009; Ohfuji and Rickard, 2005; Parkes and Sass, 2009; Pearce et al., 2006; Rabus et al., 2006; Reeburgh, 2007; Rickard and Luther, 2006, 2007; Rickard and Morse, 2005; Roberts et al., 2011; Seal et al., 2000; Sleep and Bird, 2008; Sverjensky and Lee, 2010; Tribovillard et al., 2006). Some of the content of this book has been précised in a chapter in the second edition of Treatise on Geochemistry (Rickard, in press). The diversity of these reviews in biology and chemistry as well as the Earth and environmental sciences, with the large number of recent Science and Nature papers and dedicated symposia, reflects how the biogeochemistry of sulfur-rich sediments and sedimentary rocks is currently leading the frontiers of much international natural science.

2 History of the Study of Sedimentary Sulfides

2.1 Background

Before ground positioning satellites and accurate clocks, inshore navigation was a dangerous business. The old-time sailing masters not only kept sketches of coasts and ports they had visited but also notes on color of the seawater and the nature of the sediments. The character of the seafloor was regularly sampled, usually by means of tallow on the end of a weighted rope, recorded and used to help determine position. For example, in 1773, two bomb ketches, HMS Racehorse and HMS Carcass, were dispatched on a scientific voyage to explore the Arctic Ocean. In overall command was Captain the Honorable John Constantine Phipps. A 14-year-old Mr. Horatio Nelson was midshipman on the Carcass, whose captain was Skeffington Lutwidge, later Admiral of the Red. The expedition weighed anchor on 4 June 1773. By the 31 July 1773, they were stuck fast in the ice northeast of Spitsbergen (Fig. 1) and were back in port by 17 September 1773. The expedition took soundings of the ocean floor on the continental shelf in the Norwegian Sea, possibly the first such soundings recorded from such depths. The Master reported “blue mud” from 383 fathoms.

FIGURE 1 The end of an early marine expedition: Captain Phipps’ 1773 expedition to the Arctic where he reported blue muds at 338 fathoms on the continental shelf. HMS Racehorse is being hauled out of the ice where she was stuck with her companion vessel HMS Carcass on 31^st July 1773. Midshipman Horatio Nelson was onboard the Carcass. The image is part of an oil painting by John Cleveley, who was on board, from his original ink and water color sketches.

A century later, John Murray led the first scientific marine expedition in HMS Challenger (1873–1876). The formation of this blue mud and the disappearance of sulfate from the interstitial waters was one of the early observations. He sailed out of the Clyde in Scotland and examined the sediments in the estuary. These were also “blue muds” and Murray and Irving (1895) reported the surprising decrease in the sulfate content of the interstitial water in these muds. They found that this was a characteristic feature of blue muds worldwide (Murray and Irving, 1895; Murray and Renard, 1891).

Murray and Renard (1891, p. 229) wrote:

The blue color is due to organic matter and sulphide of iron in a fine state of division.

The blue color of these muds has more recently been ascribed to the presence of finely divided pyrite (cf. Rickard and Morse, 2005) but a caveat was sounded by Rickard and Luther (2007) who pointed out that, by analogy with soils, not all blue muds were necessarily sulfidic.

Murray and Irvine (1895) concluded that the seawater sulfide was reduced to sulfides by bacterial decay of organic matter. They suggested that the sulfide reacted with ferric oxides from the surface layer to produce the iron sulfides. Interestingly, they also noted that the seawater immediately above the muds was saturated with respect to calcium carbonate and suggested that carbon dioxide was a product of the bacterial decay of organic matter. It appears that Murray and Irvine (1895) had identified the major components of the formation of sedimentary sulfides (Chapters 8 and 14). Murray and Irvine’s conclusions were substantiated by the results of Van Delden (1903) who reached similar conclusions with respect to black, sulfidic muds from canal waters.

Murray and Renard (1891) reported that sulfidic blue muds are the dominant sediment in both deep and shallow waters in all partly enclosed seas and the continental shelves and slopes. However, most of the observations of sedimentary sulfides, especially pyrite in sediments, were restricted to descriptions of individual occurrences until the second half of the twentieth century. For example, Malaguti and Durocher (1852) reported pyrite in recent sediments—again in blue muds—on the beach at Saint Malo on the Bretagne coast.

The importance of sedimentary iron sulfides to the global sulfur system was first recognized by Sugawara et al. (1953, 1954). It took more than 50 years after the Murray and his coworkers first reported the abundance of sulfidic, blue muds in the oceans for their full import to be appreciated.

One of the landmark contributions to understanding the role of sedimentary sulfides in the global biogeochemical cycles of many key elements, including O and C, was the publication in 1971 of the book Evolution of Sedimentary Rocks by Garrels and Mackenzie (1971). Holser et al. (1988) provided the first modern account on the long-term geochemical cycles of carbon a...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Acknowledgements
• Chapter 1. Introduction
• Chapter 2. Sulfur Chemistry in Aqueous Solutions
• Chapter 3. Sedimentary Iron Biogeochemistry
• Chapter 4. Aqueous Metal–Sulfide Chemistry
• Chapter 5. Metastable Sedimentary Iron Sulfides
• Chapter 6. Sedimentary Pyrite
• Chapter 7. Metal Sequestration by Sedimentary Iron Sulfides
• Chapter 8. Microbial Sulfate Reduction in Sediments
• Chapter 9. Microbial Sulfide Oxidation in Sediments
• Chapter 10. Microbial Ecology of Sulfidic Sediments
• Chapter 11. Sedimentary Sulfur Isotope Biogeochemistry
• Chapter 12. Iron Isotope Fractionation In Sedimentary Sulfides
• Chapter 13. Euxinic Systems
• Chapter 14. Sedimentary Sulfides
• Chapter 15. The Geochemistry of Sulfidic Sedimentary Rocks
• Chapter 16. Fossil Bacteria
• Chapter 17. The Evolution of the Sedimentary Sulfur Cycle
• Index