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

Citation
Sj. Wyld et Je. Wright, New evidence for Cretaceous strike-slip faulting in the United States Cordillera and implications for terrane-displacement, deformation patterns, andplutonism, AM J SCI, 301(2), 2001, pp. 150-181
Citations number
136
Language
INGLESE
art.tipo
Review
Categorie Soggetti
Earth Sciences
Journal title
AMERICAN JOURNAL OF SCIENCE
ISSN journal
0002-9599 → ACNP
Volume
301
Issue
2
Year of publication
2001
Pages
150 - 181
Database
ISI
SICI code
0002-9599(200102)301:2<150:NEFCSF>2.0.ZU;2-7
Abstract
Early to mid-Cretaceous dextral strike-slip faulting, involving up to 400 k m displacement, has been documented in the southern Sierra Nevada of Califo rnia, In western Idaho, the Salmon River suture juxtaposes unrelated oceani c and continental rocks along a major, near-vertical shear zone that was ac tive in the Early to mid-Cretaceous. These two structural zones have been t reated as separate entities; however, new data indicate that they likely co nnect via a structural discontinuity in northwest Nevada and southeast Oreg on, herein called the western Nevada shear zone (WNS). Current structures within the WNS record dip-slip contractional deformation ; however, regional relations (structural and stratigraphic) indicate a mis match in the early Mesozoic geology of rocks across the WNS that is best ex plained by dextral strike-slip displacement of several 100 km. These relati ons argue that an early strike-slip structure along the WNS was reactivated and obscured during later regional shortening deformation, most Likely rel ated to the Cretaceous Sevier orogeny. The WNS is along strike and broadly coeval with the Salmon River suture zone and strike-slip boundaries in the Sierra Nevada, We hypothesize that all these features are related elements of a major structural boundary in the western United States Cordillera, Thi s boundary is interpreted to have accommodated significant dextral strike-s lip displacement of outboard are terranes of the Cordillera in the Early Cr etaceous, followed by reactivation as a localized contractional zone in die mid-Cretaceous during the Sevier orogeny, Cretaceous batholiths of the Uni ted States Cordillera closely parallel the boundary, which we suggest forme d a major crustal flaw that localized and facilitated emplacement of are ma gmas.