Earth Processes


Book Description

Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 95. Publication of this monograph will coincide, to a precision of a few per mil, with the centenary of Henri Becquerel's discovery of "radiations actives" (C. R. Acad. Sci., Feb. 24, 1896). In 1896 the Earth was only 40 million years old according to Lord Kelvin. Eleven years later, Boltwood had pushed the Earth's age past 2000 million years, based on the first U/Pb chemical dating results. In exciting progression came discovery of isotopes by J. J. Thomson in 1912, invention of the mass spectrometer by Dempster (1918) and Aston (1919), the first measurement of the isotopic composition of Pb (Aston, 1927) and the final approach, using Pb-Pb isotopic dating, to the correct age of the Earth: close-2.9 Ga (Gerling, 1942), closer-3.0 Ga (Holmes, 1949) and closest-4.50 Ga (Patterson, Tilton and Inghram, 1953).




Modelling of Magmatic and Allied Processes


Book Description

Modeling of Magmatic and Allied Processes presents methods and models for the quantification of geological processes. Conceptual models for magmatic differentiation involving crystallization and mixing are presented and applied to field and textural data. Model equations for the degree of partial melting in presence perturbations of lithospheric geotherms and partitioning of trace/radioactive elements in the matrix and melts, and the formation of continents with melt additions are described. Diverse magmatic products are shown to result from differentiation processes rather than magmatic source heterogeneities. The degree of partial melting depends on mantle temperatures, for which parameterized thermal convection models are reviewed. Perturbations in geotherms caused by mantle heat flow, CO2 flux from great depths and tectonic thrusting are analyzed. The petrogenetic significance of accessory minerals of felsic magma evolution is assessed with the help of examples from Carpathian granitoids. Methods for simulating the 3-D Concentration and Distribution Models (DC-DMs) and fractal dimension of evolving magma systems are described with examples. The use of conventional scanning electron microscopy methods and electron microprobe to characterize and infer magmatic processes is explained, and the background and economic potential of hydrothermal systems are examined. The nature of oxidizing felsic magmas along with their potential for copper mineralization is discussed. In closing, the handling, calculation and plotting of geochemical data for igneous rock suites using the R-language-based software Geochemical Data Toolkit (GCDkit) along with plug-in modules for the forward and reverse mass-balance calculation of fractional crystallization are demonstrated.




Contact Metamorphism


Book Description

Volume 26 of Reviews in Mineralogy provides a multidisciplinary review of our current knowledge of contact metamorphism. As in any field of endeavor, we are provided with new questions, thereby dictating future directions of study. Hopefully, this volume will provide inspiration and direction for future research on contact metamorphism. The Mineralogical Society of America sponsored the short course on Contact Metamorphism, October 17-19, 1991, at the Pala Mesa Resort, Fallbrook, California, prior to its annual meeting with the Geological Society of America.




Stable Isotopes in High Temperature Geological Processes


Book Description

Volume 16 of Reviews in Mineralogy inroduces to high-temperature stable isotope geochemistry and should provide an entry into the pertinent literature, as well as some understanding of the basic concepts and potential applications. The first three chapters focus on the theory and experimental data base for equilibrium, disequilibrium, and kinetics of stable isotope exchange reactions among geologically important minerals and fluids. The fourth chapter discusses the primordial oxygen isotope variations in the solar system prior to formation of the Earth, along with a discussion of isotopic anomalies in meteorites. The fifth chapter discusses isotopic variations in the Earth's mantle and the sixth chapter reviews the variations in the isotopic compositions of natural waters on our planet. In Chapters 7, 8, 9 and 10, these isotopic constraints and concepts are applied to various facets of the origin and evolution of igneous rocks, bringing in much material on radiogenic isotopes as well, because these problems require a multi-dimensional attack for their solution. In Chapters 11 and 12, the problems of hydrothermal alteration by meteoric waters and ocean water are considered, together with discussions of the physics and chemistry of hydrothermal systems and the 18O/16O history of ocean water. Finally, in Chapters 13 and 14, these concepts are applied to problems of metamorphic petrology and ore deposits, particularly with respect to the origins of the fluids involved in those processes.




Minerals, Inclusions And Volcanic Processes


Book Description

Volume 69 of Reviews in Mineralogy and Geochemistry covers the fundamental issues of volcanology: At what depths are eruptions triggered, and over what time scales? Where and why do magmas coalesce before ascent? If magmas stagnate for thousands of years, what forces are responsible for initiating final ascent, or the degassing processes that accelerate upward motion? To the extent that we can answer these questions, we move towards formulating tests of mechanistic models of volcanic eruptions (e.g., Wilson, 1980; Slezin, 2003; Scandone et al., 2007), and hypotheses of the tectonic controls on magma transport (e.g., ten Brink and Brocher, 1987; Takada, 1994; Putirka and Busby, 2007). Our goal, in part, is to review how minerals can be used to understand volcanic systems and the processes that shape them; we also hope that this work will spur new and integrated studies of volcanic systems.




Basement Tectonics 12


Book Description

Proceedings of the Twelfth International Conference on Basement Tectonics held in Norman, Oklahoma, U.S.A., May 1995







The Early Earth


Book Description




Layered Intrusions


Book Description

Written by leading experts in the field, this work summarises the important aspects relating to layered intrusions, with almost universal coverage of the subject.Each chapter is a complete review of a theme or specific geological intrusion. The first part of the book covers the general principles and processes which apply to all intrusions. Those chapters on individual intrusions concentrate on factual information.A detailed full colour geological map of the Skaergaard intrusion is also included.This book will appeal to a wide audience - university libraries, research students in igneous petrology, state organisations such as exploration companies - as well as being an ideal textbook for university courses on igneous petrology, and geochemistry and petrography.




Magma-Rock and Magma-Mush Interactions as Fundamental Processes of Magmatic Differentiation


Book Description

During transport, a percolating melt or magma may contact rock or a magmatic mush, resulting in inevitable interactions that may be described as magma/melt-rock or magma/melt-mush interactions. Examples of these types of interactions include mantle metasomatism, mineral-melt reaction in the mantle, mineral dissolution in magma, crustal wallrock partial melting, and thermal remobilization of preexisting mushy magma (rejuvenation of mush) by intruding high specific enthalpy magma. This spectrum of processes plays a major role in the composition, thickness, and age of the mantle lithosphere and its associated crust. These interactions also impact the asthenosphere because melts that form in the deepest parts of the mantle may ascend and interact with shallower mantle during transport.