Sunday, October 18, 2009

Westward subduction in the Cordillera?

Tucson geologist Bob Hildebrand was autographing copies of his new book at the opening of the Geological Society of America Annual Meeting in Portland (Oregon) tonight. GSA Special Paper 457 is entitled "Did Westward Subduction Cause Cretaceous-Tertiary Orogeny in the North American Cordillera?" I bought a copy that Bob graciously signed.

GSA's blurb on it say,
This volume describes an iconoclastic model for the Cretaceous–Tertiary development of the Cordilleran orogen. Hildebrand argues that the orogeny was collisional in origin, caused by westerly-dipping subduction beneath an exotic ribbon continent named Rubia, and followed by development of an eastward-dipping subduction zone outboard of the collision zone. This model explains the origin of Laramide thick-skinned deformation, Cordilleran-type batholiths, early Tertiary metamorphic core complexes, Basin and Range extension, porphyry copper deposits, and the Pelona-Orocopia-Rand schists, and it helps resolve the longstanding Baja–British Columbia controversy.
Bob's very good-natured about the controversy this publication has already generated in the tectonics community. This is just the kind of out-of-the-box thinking that produces wonderful debates and helps resolve long-standing problems in the field.

A professor friend told me he intends to use the volume as a text in one his classes.


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