New evidence for Cretaceous strike-slip faulting in the United States Cordillera and implications for terrane-displacement, deformation patterns, and plutonism

摘要: Early to mid-Cretaceous dextral strike-slip faulting, involving up 400 km displacement, has been documented in the southern Sierra Nevada of California. In western Idaho, Salmon River suture juxtaposes unrelated oceanic and continen- tal rocks along a major, near-vertical shear zone that was active mid-Cretaceous. These two structural zones have treated as separate entities; however, new data indicate they likely connect via discontinuity northwest southeast Oregon, herein called (WNS). Current structures within WNS record dip-slip contractional deformation; regional relations (structural stratigraphic) mismatch early Mesozoic geology across is best explained by displacement several 100 km. argue an structure reactivated obscured during later shortening deformation, most related Cretaceous Sevier orogeny. The strike broadly coeval with boundaries Nevada. We hypothesize all these features are elements major boundary United States Cordil- lera. This interpreted accommodated significant outboard arc terranes Cordillera Cretaceous, followed reactivation localized batholiths closely parallel boundary, which we suggest formed crustal flaw facilitated emplacement magmas.