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Table of Contents - Special Paper 457

Did Westward Subduction Cause Cretaceous–Tertiary Orogeny in the North American Cordillera?

by Robert S. Hildebrand

Abstract 1
Introduction 2
Geological Overview of the Cordillera 4
Why Current Models Fail 5
The Passive Margin and Westward Correlations 7
Fold-Thrust Belt and Exotic Slices 10
The Hinterland Belt 13
Failed Subduction of North America 18
Age of Thrusting and Collision 19
Exotic Rocks Generally Considered Part of North America 20
The Superterrane 23
The Suture 24
Slab Break-Off and Development of Metamorphic Core Complexes 26
Laramide Uplifts and Thick-Skinned Deformation 27
Slab Break-Off Magmas and the Segmented North American Plate 28
Cordilleran-Type Batholiths and Subducted Crust 31
Postcollisional Magmatism on North America 36
Triangle Zone 36
Mojave-Sonoran Segment 37
The Case for the Phoenix Fault 40
Mojave-Sonora Megashear and Orocopia-Pelona-Rand Schists 44
Porphyry Copper Deposits 44
Baja-BC and Strike-Slip Faults 46
Origin and Significance of Early to Mid-Tertiary Extension 46
Summary of the Evolution of the Cordilleran Orogen 49
Discussion 52
Problems Deserving Additional Study 53
New Directions 53
Acknowledgments 54
References Cited 54