Fracture patterns associated with the evolution of the Teton anticline, Sawtooth Range, Montana, USA
Published:January 02, 2020
C. M. Burberry, D. L. Cannon, J. W. Cosgrove, T. Engelder, 2020. "Fracture patterns associated with the evolution of the Teton anticline, Sawtooth Range, Montana, USA", Folding and Fracturing of Rocks: 50 Years of Research since the Seminal Text Book of J. G. Ramsay, C. E. Bond, H. D. Lebit
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The Teton anticline and adjacent structures, in the Sawtooth Range, Montana, USA, are fractured in such a way that may be taken as a model for fractures propagating during buckle folding. However, advances in understanding both the process of folding in forelands and the evolution of fracture patterns found within these folds suggest that it is time to reinterpret the nexus between fracturing and folding within these classic structures. With the benefit of seismic lines, the Teton anticline is best described as a fault-propagation fold. Joint propagation initiated with the formation of two major sets whose orientation is controlled by pre-folding, regional stresses. Two more joint sets propagated in local stress fields, developed in response to anticline growth. Some early joints were reactivated as wrench faults during amplification and tightening of the anticlines. The fracture sets identified are consistent with: (a) propagation in a regional stress field, which may be related to stretching in the Sawtooth Range orocline; and (b) tangential longitudinal strain of the backlimb and forcing or trishear of the forelimb during anticline development. Thus, we suggest that fracture networks across folded structures should be interpreted and characterized in the light of the geological history of the entire system.
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Folding and Fracturing of Rocks: 50 Years of Research since the Seminal Text Book of J. G. Ramsay
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This Special Publication is a celebration of research into the Folding and Fracturing of Rocks to mark the 50th anniversary of the publication of the seminal textbook by J. G. Ramsay. Folding and Fracturing of Rocks summarised the key structural geology concepts of the time. Through his numerical and geometric focus John pioneered and provided solutions to understanding the processes leading to the folding and fracturing of rocks. His strong belief that numerical and geometric solutions, to understanding crustal processes, should be tested against field examples added weight and clarity to his work. The basic ideas and solutions presented in the text are as relevant now as they were 50 years ago, and this collection of papers celebrates John's contribution to structural geology. The papers explore the lasting impact of John and his work, they present case studies and a modern understanding of the process documented in the Folding and Fracturing of Rocks.