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Author: Henry V. Lyatsky Publisher: Springer ISBN: 3540495983 Category : Science Languages : en Pages : 332
Book Description
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.
Author: Henry V. Lyatsky Publisher: Springer ISBN: 3540495983 Category : Science Languages : en Pages : 332
Book Description
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.
Author: C.A. Burk Publisher: Springer ISBN: 3662011417 Category : Science Languages : en Pages : 976
Book Description
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.
Author: Daniel Lizarralde Publisher: ISBN: Category : Continental margins Languages : en Pages : 456
Book Description
Many of the most important processes that create and modify continental crust occur at continental margins, but recently has the scientific community acquired the necessary intrumentation to image crustal structure across margins in detail. In this thesis we investigate the crustal structure across the U.S. East Coast rifted margin and the convergent margin of southwestern Alaska using modern, deep-penetrating marine seismic reflection/refraction data. We consider U.S. East Coast margin transects along the shelf offshore Georgia and across the mid-Atlantic margin near Chesapeak bay. Results by other workers, based on data from these transects, have shown that voluminous volcanism accompanied formation of the rifted margin during continental breakup. Results presented in this thesis constrain the landward extent of rift-related magmatic emplacement. We find that magmatic intrusion and underplating of pre-existing continental crust occurs primarily in extended crust and that crustal extension is focused in a 75-km-wide region beneath the shelf and slope. The crust thinned by 50 to 80% within this interval and then seafloor spreading began with an unusually large volume of igneous crust production. The initial volcanic extrusives were emplaced subaerially and are now present beneath the sediments in a thick seaward-dipping wedge. We use post-stack depth migration to image this wedge and use the resulting image to consider the early subsidence of the margin. The geometry of the subaerially extruded rift volcanics suggest that the margin subsided rapidly once volncanism began. We infer from the subsidence, the along-margin distribution of magmatic material, and the across-margin localization of magmatic emplacement and deformation that the U.S. East Coast rift volcanics had an anomalously-hot mantle source whose distribution beneath the lithosphere prior to rifting was long (the length of the margin) but not deep. We speculate that the distribution of this material was controlled by topography at the base of the lithosphere inherited from the Paleozoic collision of North America and Africa. Our analysis of the southwestern Alaska convergent margin is based on data from the 1994 Aleutian seismic experiment. The crust of most of Alaska has been built through terrane accretion and arc magmatism, and this experiment was conducted to study the evolution of continental crust through these processes. We consider transects across the westernmost Alaska Peninsula margin, where subduction is occurring beneath protocontinental crust composed of oceanic-arc terranes accreted in the Cretaceous, and across Bristol Bay in the back arc region where the crust has undergone a number of geologic events since accretion. Across the Peninsula, we find that the velocity structure of the accreted terranes differs little from that of the Cenozoic Aleutian oceanic-arc crust west of the Peninsula determined along another transect of this experiment. The accreted oceanicarc terranes are considerably more mafic than continental crust and the process of accretion has apparently not modified the bulk composition of these terranes toward that of average continental crust. It is possible that Cenozoic arc magmatism has been more felsic in composition than that which formed the accreted terranes and the Aleutian oceanic arc to the west, and that these magmas have been emplaced primarily within the crust inboard of the accreted terranes which lie south of the currently active arc. The geology of the Bristol Bay region suggests that the crustal components here had an origin similar to that of the Alaska Peninsula margin- that is, accreted terranes. We find, however, that the crust beneath Bristol Bay has a typically continental velocity structure. If this crust originally had a structure similar to the Alaska Peninsula margin, then at least two processes must have occured to affect the transformation to its current structure: crustal thickening and removal of the mafic lower crust. The geologic events that have affected this region since accretion are consistent with such and evolution.
Author: Steven Earle Publisher: ISBN: 9781537068824 Category : Languages : en Pages : 628
Book Description
This is a discount Black and white version. Some images may be unclear, please see BCCampus website for the digital version.This book was born out of a 2014 meeting of earth science educators representing most of the universities and colleges in British Columbia, and nurtured by a widely shared frustration that many students are not thriving in courses because textbooks have become too expensive for them to buy. But the real inspiration comes from a fascination for the spectacular geology of western Canada and the many decades that the author spent exploring this region along with colleagues, students, family, and friends. My goal has been to provide an accessible and comprehensive guide to the important topics of geology, richly illustrated with examples from western Canada. Although this text is intended to complement a typical first-year course in physical geology, its contents could be applied to numerous other related courses.
Author: Louis Charles Pakiser Publisher: Geological Society of America ISBN: 081371172X Category : Science Languages : en Pages : 843
Book Description
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.
Author: Kenneth D. Ridgway Publisher: Geological Society of America ISBN: 0813724317 Category : Science Languages : en Pages : 676
Book Description
"The convergent margin of southern Alaska is considered one of the type areas for understanding the growth of continental margins through collisional tectonic processes. Collisional processes that formed this margin were responsible for multiple episodes of sedimentary basin development, subduction complex growth, magmatism, and deformation. Two main collisional episodes shaped this Mesozoic-Cenozoic continental margin. The first event was the Mesozoic collision of the allochthonous Wrangellia composite terrane. This event represents the largest addition of juvenile crust to western North America in the past 100 m.y. The second event is the ongoing collision of the Yakutat terrane along the southeastern margin of Alaska. This Cenozoic event has produced the highest coast mountain range on Earth (Saint Elias Mountains), the Wrangell continental arc, and sedimentary basins throughout southern Alaska. Active collisional processes continue to shape the southern margin of Alaska, mainly through crustal shortening and strike-slip deformation, large-magnitude earthquakes, and rapid uplift and exhumation of mountain belts and high sedimentation rates in adjacent sedimentary basins. This volume contains 24 articles that integrate new geophysical and geologic data, including many field-based studies, to better link the sedimentary, structural, geochemical, and magmatic processes that are important for understanding the development of collisional continental margins."--Publisher's website.
Author: Henry Lyatsky Publisher: Springer ISBN: 3540493964 Category : Science Languages : en Pages : 487
Book Description
Steep crystalline-basement faults, commonly indicated by potential-field anomalies, played a crucial role in evolution of continental cratonic platforms. In the Phanerozoic Western Canada Sedimentary Province, history of crustal block movements and warps is reconstructed from the distribution of depocenters, lithofacies and structures in structural-formational étages in sedimentary cover. Each étage is a rock succession formed during a particular tectonic stage; regional tectonic restructuring closes each stage, and the next stage represents a new tectonic regime. Practical tectonic analysis, based on observation of rocks and geophysical data, is a reliable guide for deciphering a region's geologic history and for resource exploration.