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This book provides a comprehensive summary of research to date in the field of stable iron isotope geochemistry. Since research began in this field 20 years ago, the field has grown to become one of the major research fields in "non-traditional" stable isotope geochemistry. This book reviews all aspects of the field, from low-temperature to high-temperature processes, biological processes, and cosmochemical processes. It provides a detailed history and state-of-the art summary about analytical methods to determine Fe-isotope ratios and discusses analytical and sample prospects.
There are no books published on this subject yet. Only review articles and review book chapters have been written so far. Perhaps the most comprehensive ones were published in 2004 in the Reviews in Geochemistry and Cosmochemistry series under the title "Geochemistry of non-traditional isotopes". Brian Beard and Clark Johnson wrote two chapters devoted to Fe isotopes. However, because the target was the specialist audience and this field expands so rapidly, this book is already partly outdated.
The stable chromium (Cr) isotope system has emerged over the past decade as a new tool to track changes in the amount of oxygen in earth's ocean-atmosphere system. Much of the initial foundation for using Cr isotopes (δ53Cr) as a paleoredox proxy has required recent revision. However, the basic idea behind using Cr isotopes as redox tracers is straightforward—the largest isotope fractionations are redox-dependent and occur during partial reduction of Cr(VI). As such, Cr isotopic signatures can provide novel insights into Cr redox cycling in both marine and terrestrial settings. Critically, the Cr isotope system—unlike many other trace metal proxies—can respond to short-term redox perturbations (e.g., on timescales characteristic of Pleistocene glacial-interglacial cycles). The Cr isotope system can also be used to probe the earth's long-term atmospheric oxygenation, pointing towards low but likely dynamic oxygen levels for the majority of Earth's history.
The interdisciplinary field of Astrobiology constitutes a joint arena where provocative discoveries are coalescing concerning, e.g. the prevalence of exoplanets, the diversity and hardiness of life, and its increasingly likely chances for its emergence. Biologists, astrophysicists, biochemists, geoscientists and space scientists share this exciting mission of revealing the origin and commonality of life in the Universe. The members of the different disciplines are used to their own terminology and technical language. In the interdisciplinary environment many terms either have redundant meanings or are completely unfamiliar to members of other disciplines. The Encyclopedia of Astrobiology serves as the key to a common understanding. Each new or experienced researcher and graduate student in adjacent fields of astrobiology will appreciate this reference work in the quest to understand the big picture. The carefully selected group of active researchers contributing to this work and the expert field editors intend for their contributions, from an internationally comprehensive perspective, to accelerate the interdisciplinary advance of astrobiology.
"Isotope Tracers in Catchment Hydrology" is the first synthesis of physical hydrology and isotope geochemistry with a catchment focus, and is a valuable reference for professionals and students alike in the fields of hydrology, hydrochemistry, and environmental science.
Explores the many facets of redox exchanges that drive magma's behavior and evolution, from the origin of the Earth until today The redox state is one of the master variables behind the Earth's forming processes, which at depth concern magma as the major transport agent. Understanding redox exchanges in magmas is pivotal for reconstructing the history and compositional make-up of our planet, for exploring its mineral resources, and for monitoring and forecasting volcanic activity. Magma Redox Geochemistry describes the multiple facets of redox reactions in the magmatic realm and presents experimental results, theoretical approaches, and unconventional and novel techniques. Volume highlights include: Redox state and oxygen fugacity: so close, so far Redox processes from Earth’s accretion to global geodynamics Redox evolution from the magma source to volcanic emissions Redox characterization of elements and their isotopes The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
Small, but significant fractionation of Fe isotopes occurs in high-temperature igneous rocks. Despite increasing study, the exact causes of this fractionation are still debated. Therefore, a systematic study of a complete igneous intrusive system is presented to evaluate the extent and causes of Fe isotope fractionation. The Eocene Skaergaard layered mafic intrusion, SE Greenland has a relatively simple magmatic history and localized superimposed alteration, which makes it a good setting to study Fe isotope fractionation. High-precision Fe isotope compositions ([delta]Fe56, relative to igneous rocks, in ‰) are presented for bulk rocks and bulk Fe-Ti oxides (magnetite-ilmenite) from a suite of 26 gabbros and ferrodiorites that encompasses the magmatic/alteration history of the Skaergaard intrusion. The [delta]Fe56 values of bulk rocks differ only by 0.074‰ (-0.043±0.013‰ to +0.031±0.027; avg. = -0.007±0.012‰, 2-SE; n = 11) and show a lack of or a slight variation with magmatic evolution as measured by plagioclase compositions and bulk-rock geochemistry. These bulk-rock [delta]Fe56 values remain within the 2-SE of the average mafic-intermediate composition of the Earth's crust (0.00±0.08‰ ). The lack of clear measurable trends in [delta]Fe56 values of Skaergaard bulk rocks as a function of magmatic evolution outside of analytical error is consistent with data from other mafic and ultramafic intrusions in that [delta]Fe56 values do not vary as much as in high-silica igneous rocks. In contrast, [delta]Fe56 values of Fe-Ti oxides throughout the evolution vary significantly, up to 0.69‰ (-0.179±0.010‰ to +0.508±0.012‰ , 2-SE; n = 26). A positive correlation between [delta]Fe56 values and Fe3+:Fe2+ ratios for bulk Fe-Ti oxides shows that their Fe isotope compositions are controlled by their Fe3+:Fe2+ ratio. Similar trends of [delta]Fe56 variations in Fe-Ti oxides and previously modeled fO2 values through the Layered Series seem to suggest that Fe isotope fractionation in Fe-Ti oxides may be driven by redox changes of the magma, but this is not seen in bulk rocks. The removal of iron via partial or complete magnetite dissolution by hydrothermal fluids may account for Fe isotope variations in bulk Fe-Ti oxides from highly altered rocks. Secondary minerals, not analyzed but replacing altered Fe-Ti oxides, likely have the light Fe isotopes removed from magnetite that results in high [delta]Fe56 values, and this difference can explain why altered and fresh bulk rocks do not differ in [delta]Fe56 values. Compared to the average Fe isotope composition of the Earth's mantle and chondritic meteorites, the average [delta]Fe56 value of Skaergaard bulk rocks is higher by 0.053‰ and 0.081‰, respectively. The higher [delta]Fe56 average of Skaergaard rocks is similar to that of terrestrial basalts, which record an average [delta]Fe56 value (+0.006±0.007‰ ) ~ 0.07‰ higher than mantle values. Further detailed Fe isotope studies of large mafic igneous intrusions will help better understand the mechanisms that produce the observed differences in [delta]Fe56 values between terrestrial mafic rocks and those of other planetary bodies.