Continental Crust Structures On The Continental Margin Of Western North America

The NE Pacific Ocean is considered the birthplace of many fundamental ideas for modern plate tectonics theory. In this book the orogenic belts of this region are discussed in a single, internally consistent tectonic concept. Geological information is considered the most reliable. Geophysical models are tested for compatibility with observable geological data. The new concept avoids force-fitting interpretations to preconceived assumptions regarding accreted far-traveled terranes in the Cordillera and continental-oceanic plate interactions in the entire region.

The continental margins of the world constitute the most impressive and largest physiographic feature of the earth's surface, and one of fundamentally great geological significance. Continental margins have been the subject of increasing attention in recent years, an interest focused by a body of new data that has provided new insights into their character. This interest was further stimulated by the realization that, in addition to the abundant living resources, continental margins contain petroleum and mineral resources that are accessible with existing technology. This realization, along with their basic geological importance, has provoked further research into the nature of continental margins throughout the world. A summary of these findings, as related to both recent and ancient continental margins, is the subject of this book. At various times in the past we had been approached individually to prepare a basic reference to continental margins; we then proposed to do such a volume jointly. However, the stimulus for the present volume eventually arose from a Penrose Conference arranged through the Geological Society of America. This conference was attended by specialists of numerous disciplines and from throughout the world, many of whom insisted that such a volume would be both timely and useful. Consequently, we agreed to undertake the task of assembling this book, with the objectives of making it available as soon and as inexpensively as possible.

The 8th International Conference on Basement Tectonics was held in Butte, Montana, August 8-12,1988. Historically, basement tectonics conferences have focused on such topics as reactivation of faults, the influence of basement faults on metallogeny and hyrocarbon accumulation, and the use of geophysical and remote sensing techniques to interpret subsurface and surface geology. The 8th Conference diverged from past conferences in that a unifying theme was selected. Because ancient major terrane or cratonic boundaries are often postulated to be fault zones which are subsequently reactivated, the conference was organized to examine all aspects of ancient continental margins and terrane boundaries and to compare younger (Mesozoic) ones, about which more is known, with older (Paleozoic and Precambrian) ones. Moreover, because the 8th Conference was held in the northwestern United States, a greater emphasis was placed on the Mesozoic margin of western North America and the North American shield. The seven oral sessions and four poster sessions all dealt with aspects of the conference theme: characterization and comparison of ancient continental margins. The organizers extend their thanks to those individuals who graciously consented to serve as moderators for the oral sessions: John M. Bartley, Mark S. Gettings, M. Charles Gilbert, John M. Guilbert, Donald W. Hyndman, William P. Leeman, Robert Mason, and A. Krishna Sinha. The program with abstracts volume was prepared by S. E. Lewis and M. J. Bartholomew.

Understanding the structure and nature of movements within the Earth's crust has become increasingly important as we try to understand the history of the Earth and try to use this knowledge as a key to events in the future. This is especially relevant to those everincreasing communities populating the edges of the Pacific Ocean. This collection of papers deals with the tectonic modelling and evolution in some of the most seismically active regions in the world. Structural and stratigraphical analysis, together with geophysical, petrological and geochemical data give us some insight into tectonic events from the past and how they affected ancient landforms, and gives us a clearer understanding of earth movements and, therefore, allows us to predict catastrophic events such as earthquakes with greater accuracy.

Developments in Geotectonics, 15: Crustal Properties across Passive Margins covers the papers presented at the symposium ""Crustal Properties across Passive Margins"", held at Dalhousie University in Halifax, Nova Scotia on June 19-23, 1978. The book focuses on theoretical modelling of the rheological properties in the upper mantle beneath oceans and continents and stratigraphic studies of the sedimentary basins. The selection first offers information on seismic refraction study of the continental edge off the Eastern United States and gravity field of the U.S. Atlantic continental margin. Topics include crustal sections, inner and outer quiet zones, alternative models and complications, gravity models, free-air anomaly map, and the ocean-continent transition zone. The text then takes a look at the geologic history of the passive margin off New England and the Canadian Maritime Provinces and geophysical observations bearing upon the origin of the Newfoundland Ridge. The manuscript elaborates on the age and origin of the deepest correlative structures recognized off Canada and Europe and geophysical transects of the Labrador Sea. Discussions focus on magnetics and gravity, stratigraphic control, consequences regarding subduction or rifting, and deep structures of the Grand Banks of Newfoundland. The selection is a dependable reference for readers interested in crustal properties across passive margins.

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.