Ebook: Basement Tectonics 8: Characterization and Comparison of Ancient and Mesozoic Continental Margins

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.

---

The Proceedings of the Eighth International Basement Tectonics Conference examines the tectonics of Mesozoic and older continental margins. Internationally recognized experts in a variety of fields -- igneous and metamorphic petrology, geophysics, structural geology, metallogeny, geochronology -- reviewed broad, key, integrative aspects of major fields that contribute to knowledge of the tectonics of margins. Many other presentations represented new, recently completed studies of specific areas or problems. The Penrose style of presentation ensured the cross fertilization of interdisciplinary ideas within the constraints that one field superimposes on another.
The introductory chapter deals with specific concepts, techniques, and ambiguities applicable to the tectonics of continental margins. An entire chapter is devoted to the relationship of metallogeny and continental margins with a major emphasis on the occurrence of gold.
The tectonic development of many Archean, Proterozoic, and even Paleozoic orogenic belts is commonly obscure or poorly constrained because erosion or subsequent tectonism has often obliterated important tectonic `keys' recorded in rocks of shallower crustal levels leaving only deeper crustal rocks juxtaposed. By comparison, a high degree of understanding has evolved regarding the complex tectonics (e.g. terrane accretion, development of metamorphic core complexes) of the convergent margin of the North American Cordillera. The second chapter is exclusively devoted to many superlative comparative aspects of the Cordilleran Mesozoic margin. Characterization of Precambrian margins, particularly of the North American craton, is the subject of another chapter. Aspects of the divergent margins of the late Proterozoic and Mesozoic Appalachian orogen, as well as its Paleozoic convergent margin, are described in a single chapter.
Problems at margins in Europe, Asia, Africa and the circum-Pacific region are discussed in several chapters.