Iron is a remarkable element in its relatively high abundance for its mass and its sensitivity to (and control of) redox on a planetary scale over geologic time. Numerous volumes have been written on iron geochemistry, and here we provide an in-depth review of iron geochemistry from the isotopic perspective. Stable iron isotope geochemistry is a relatively new field, belonging to what is sometimes called “non-traditional” stable isotopes. There have been a number of reviews of this field of isotope geochemistry, the most recent of which is found in Teng et al. (2017) in their Reviews in Mineralogy and Geochemistry volume 82, published by the Mineralogical Society of America and the Geochemical Society. In chapter 11 of this volume, Dauphas et al. (2017) review iron isotope systematics. <...>

This preface presents the background to this book, the second volume of the "Hydrothermal Iron Oxide Copper-Gold & Related Deposits - A Global Perspective" series, and briefly discusses the rationale for inviting the papers it contains, their format and what it is hoped the volume will achieve. It also offers some observations on the unifying characteristics of the iron oxide copper-gold family of deposits and what they may represent in a broader context.

Abstract - The magnetite-apatite deposits ("Kiruna-type") and the iron oxide-Cu-Au deposits form end members of a continuum. In general the magnetite-apatite deposits form prior to the copper-bearing deposits in a particular district. While the magnetite-apatite deposits display remarkably similar styles of alteration and mineralization from district to district and throughout geologic time, the iron oxide-Cu-Au deposits are much more diverse. Deposits of this family are found in post-Archean rocks from the Early Proterozoic to the Pliocene. There appear to be three "end member" tectonic environments that account for the vast majority of these deposits: (A) intra-continental orogenic collapse; (B) intra-continental anorogenic magmatism; and (C) extension along a subduction-related continental margin. All of these environments have significant igneous activity probably related to mantle underplating, high heat flow, and source rocks (subaerial basalts, sediments, and/or magmas) that are relatively oxidized; many districts contain(ed) evaporites. While some of the magnetite-apatite deposits appear to be directly related to specific intrusions, iron oxide-Cu-Au deposits do not appear to have a direct spatial association with specific intrusions. Iron oxide-Cu-Au deposits are localized along high- to low-angle faults which are generally splays off major, crustal-scale faults. Iron oxide-Cu-Au deposits appear to have formed by: 1) significant cooling of a fluid similar to that responsible for precipitation of magnetite-apatite; 2) interaction of a fluid similar to that causing precipitation of magnetite-apatite with a cooler, copper-, gold-, and relatively sulfate-rich fluid of meteoric or "basinal" derivation; or 3) a fluid unrelated to that responsible for the magnetite-apatite systems but which is also oxidized and saline, though probably cooler and sulfate-bearing. The variability of potential ore fluids, together with the diverse rock types in which these deposits are located, results in the wide variety of deposit styles and mineralogies.

This book is an educational monograph addressed to graduate students and others undertaking isotope effect research. The fundamental principles needed to understand isotope effects are presented in appropriate detail. While it is true that these principles in the beginning will be more familiar to students of physical chemistry, and some background in physical chemistry is strongly recommended, the text provides enough detail to make the book an asset to students in organic and biochemistry, and geochemistry. Isotope effects are widely employed in many fields of science because of their utility. The underlying scientific principles needed to apply isotope effects to problems in physical chemistry, in organic and biochemistry, and in geochemistry are all the same or similar. This accounts for widespread communication between scientists in very different disciplines who share a fundamental interest in isotope effects. Nowhere has this been better exemplified than at the Gordon Conference on Isotope Effects which has met regularly for more than 50 years and has just as regularly stimulated cooperative efforts. <...>