Geophysical Framework Of The Continental United States

A review and evaluation of our knowledge of the structure of the crust and upper mantle of the continental United States, exclusive of Alaska, as determined from geophysical observations. Covers geophysical methods of studying the crust and upper mantle; a region-by-region review of crustal and upper-mantle structure; continental overviews based on the different geophysical methods; and geologic and petrologic syntheses based largely on the geophysical results.

"This book contains landmark papers on the processes of formation of continental crust from its beginnings in the Archean to modern processes, as well as discussions of several ancient and modern orogenic belts. The book is international in scope, with contributions from geoscientists dealing with crustal processes on five continents, and articles from more than 50 non-U.S. authors and co-authors."--Publisher's website.

Summaries of the major features of the geology of North America and the adjacent oceanic regions are presented in 20 chapters. Topics covered include concise reviews of current thinking about Precambrian basement, Phanerozoic orogens, cratonic basins, passive-margin geology of the Atlantic and Gulf Coast regions, marine and terrestrial geology of the Caribbean region and economic geology.

Variations in seismic Q are sensitive to a much greater extent than are seismic velocity variations on factors such as temperature, fluid content, and the movement of solid state defects in the earth. For that reason an understanding of Q and its variation with position in the earth and with time should provide information in earth's tectonic evolution, as well as on aspects of its internal structure. Progress in understanding Q has suffered from difficulty in obtaining reliable amplitude data at global and temporary stations. Moreover, laboratory determinations of Q, until recently, were most often made at frequencies much higher than those measured by seismologists for waves propagating through the earth. Recent advances in seismic station distribution and quality, as well as in methodology at both high and low fequencies, have greatly improved the quality of observational data available to seismologists from global stations. Concurrent advances have been made in measuring Q using laboratory samples at frequencies that pertain to the earth and in theoretical understanding of seismic wave attenuation. Papers of this volume present new information on Q in the earth from several perspectives: methodology, results from global and regional observations of both body and surface waves, laboratory measurements, and theoretical understanding. The editors believe that we have reached a new threshold in Q studies and that advances in data quality and methodology will spur increased interest in this difficult, but interesting field.