Lithospheric Discontinuities

A multidisciplinary update on continental plate tectonics and plate boundary discontinuities Understanding the origin and evolution of the continental crust continues to challenge Earth scientists. Lithospheric Discontinuities offers a multidisciplinary review of fine scale layering within the continental lithosphere to aid the interpretation of geologic layers. Once Earth scientists can accurately decipher the history, internal dynamics, and evolution of the continental lithosphere, we will have a clearer understanding of how the crust formed, how plate tectonics began, and how our continents became habitable. Volume highlights: Theories and observations of the current state of tectonic boundaries and discontinuities Contributions on field observations, laboratory experiments, and geodynamic predictions from leading experts in the field Mantle fabrics in response to various mantle deformation processes Insights on fluid distribution using geophysical observations, and thermal and viscosity constraints from dynamic modeling Discontinuities associated with lithosphere and lithosphere-asthenosphere boundary An integrated study of the evolving physical and chemical processes associated with lithosphere asthenosphere interaction Written for academic and researchgeoscientists, particularly in the field of tectonophysics, geophysicists, geodynamics, seismology, structural geology, environmental geology, and geoengineering, Lithospheric Discontinuities is a valuable resource that sheds light on the origin and evolution of plate interaction processes.

The ensemble of manuscripts presented in this special volume captures the stimulating cross-disciplinary dialogue from the International Symposium on Deep Structure, Composition, and Evolution of Continents, Harvard University, Cambridge, Massachusetts, 15-17 October 1997. It will provide an update on recent research developments and serve as a starting point for research of the many outstanding issues. After its formation at mid-oceanic spreading centers, oceanic lithosphere cools, thickens, and subsides, until it subducts into the deep mantle beneath convergent margins. As a result of this continuous recycling process oceanic lithosphere is typically less than 200 million years old (the global average is about 80 Myr). A comprehensive, multi-disciplinary study of continents involves a wide range of length scales: tiny rock samples and diamond inclusions may yield isotope and trace element signatures diagnostic for the formation age and evolution of (parts of) cratons, while geophysical techniques (e.g., seismic and electromagnetic imaging) constrain variations of elastic and conductive properties over length scales ranging from several to many thousand kilometers. Integrating and reconciling this information is far from trivial and, as several papers in this volume document, the relationships between, for instance, formation age and tectonic behavior on the one hand and the seismic signature, heat flow, and petrology on the other may not be uniform but may vary both within as well as between cratons. These observations complicate attempts to determine the variations of one particular observable (e.g., heat flow, lithosphere thickness) as a function of another (e.g., crustal age) on the basis of global data compilations and tectonic regionalizations. Important conclusions of the work presented here are that (1) continental deformation, for instance shortening, is not restricted to the crust but also involves the lithospheric mantle; (2) the high wavespeed part of continental lithospheric mantle is probably thinner than inferred previously from vertically travelling body waves or form global surface-wave models; and (3) the seismic signature of ancient continents is more complex than expected from a uniform relationship with crustal age.

Previously published as part of the 1993 subscription to the journals: Physics of the Earth and Planetary Interiors, Volume 79, Nos. 1/2, Tectonophysics, Volume 223, Nos. 1/2, Chemical Geology, Volume 108, Nos. 1/4, Sedimentary Geology, Volume 86, Nos. 1/2, Global and Planetary Change, Volume 8, Nos. 1/2, Marine Geology, Volume 113, Nos. 1/2, Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 103, Nos. 1/2 This is a selection of keynote papers that were presented at the Interdisciplinary Union Symposia of the 7th conference of the European Union of Geosciences (EUG) from 4 to 8 April 1993 in Strasbourg. It contains both chapters reporting on forefront research as well as review articles. Since the interdisciplinary approach in the earth sciences is increasingly important, the scope of the book is wide with contributions from geology, geophysics, geochemistry and adjacent fields in biology. In a similar spirit, problems dealing with the earth's mantle as well as topics related to shallower levels in the earth and coupled earth-ocean-atmosphere systems are part of this volume. As such it provides a survey of recent advances in a wide range of fields of the earth sciences.

The Treatise on geophysics is the only comprehensive, state-of-the-art, and integrated summary of the present state of geophysics. Offering an array of articles from some of the top scientists around the world, this 11-volume work deals with all major parts of solid-Earth geophysics, including a volume on the terrestrial planets and moons in our Solar System. This major reference work will aid researchers, advanced undergrad and graduate students, as well as professionals in cutting-edge research.