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Published May 1988 | public
Journal Article

Escape hypothesis for the Stikine block

Abstract

Comparison of stratigraphic, faunal, and paleomagnetic characteristics of the Stikine terrane of British Columbia with other terranes in the Cordilleran collage reveals broad similarities with a group of terranes that formed a volcanic belt marginal to North America in Paleozoic and early Mesozoic time. Unlike Stikine, these terranes lie inboard of another belt of terranes that represents an early Mesozoic subduction complex or melange belt. Thus, in British Columbia the marginal volcanic belt is apparently doubled. In the Columbia embayment region, the marginal volcanic and melange belts are missing, and rocks of the outermost major component of the collage, the Wrangellia superterrane, are juxtaposed directly against cratonic rocks. We propose that Stikine is the missing fragment from the Columbia embayment; its northward "tectonic escape" was driven by the early stages of collision of the Wrangefia superterrane with North America in Middle to Late Jurassic time. The escaped fragment was then trapped between melange and more northerly, later arriving parts of the Wrangellia superterrane in Early to mid-Cretaceous time.

Additional Information

© 1988 Geological Society of America. Manuscript received June 25, 1987; Revised manuscript received February 8, 1988; Manuscript accepted February 18, 1988. Supported by National Science Foundation Grant EAR-8451181 to Wernicke and Grant EAR-7713637 to B. C. Burchfiel; a grant from the Shaler and Clifford P. Hickock Junior Faculty Development Funds of Harvard University; and the Geological Survey of Canada. We thank J. O. Wheeler, B. C. Burchfiel, M. F. Folio, Karen Lund, J.W.H. Monger, and L. W. Snee for fruitful discussions. Careful reviews by M. T. Brandon and D. J. Tempelman-Kluit contributed greatly to the clarification of ideas presented here.

Additional details

Created:
August 22, 2023
Modified:
October 26, 2023