Editors: John B. Brady, H. Robert Burger, John T. Cheney, and Tekla A. Harms
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The Tobacco Root Mountains occupy a unique niche in the Archean Wyoming province of North America. Located near the northwestern margin of the province, the Precambrian rocks of the Tobacco Root Mountains were subjected to an intense tectonothermal event (Big Sky Orogeny) during the collision of the Wyoming and Hearne provinces in the Early Proterozoic. This event overprinted earlier periods of deformation and metamorphism, but the unique lithologic packages present in the Tobacco Root Mountains aid in unraveling early from later events and in detailing many results stemming from this Early Proterozoic collision. Several papers in this volume review the geochemistry and petrology of the four major Precambrian rock sequences present in the Tobacco Root Mountains, focusing on what each rock suite represents in terms of original protolith and providing the foundation for understanding the extensive petrological and geochronological information that follows. Another paper considers the meta-ultramafic rocks that are dispersed throughout all Precambrian exposures in the Tobacco Root Mountains. Petrologic observations from all four rock suites are interpreted in terms of a metamorphic history and a pressure-temperature path for the Tobacco Root Mountains during the Proterozoic event. Numerous and extensive radiometric age determinations from all four major rock suites are presented subsequent papers. Taken together, the papers provide a solid base for understanding the timing of the tectonothermal events that affected these rock suites and for separating the effects of the last major event in the Early Proterozoic. Finally, two papers examine the structures and fabrics present in the Precambrian rocks and synthesize observed field relations, structures and fabrics with age determinations and metamorphic history into a sequence of events by which the rocks of the Tobacco Root Mountains evolved, placing Tobacco Root geology into the context of the northern Wyoming province
Published: 5/14/2004
ISBN Number: 0813723779
Pages: 256
Product Category: Special Papers