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TitleSeismic evidence for a mantle suture and implications for the origin of the Canadian Cordillera
AuthorChen, Y; Gu, Y J; Currie, C A; Johnston, S T; Hung, S -H; Schaeffer, A JORCID logo; Aufet, P
SourceNature Communications vol. 10, 2249, 2019 p. 1-10, Open Access logo Open Access
LinksSeismic data for USArray, RAVEN, and CANOE networks (IRIS Data Management Center)
LinksSeismic data for CNSN network (Canadian National Data Centre)
LinksTraveltime data
Alt SeriesNatural Resources Canada, Contribution Series 20190343
PublisherSpringer Nature
Mediapaper; on-line; digital
File formatpdf; html
ProvinceAlberta; British Columbia; Saskatchewan
NTS64K; 64L; 72; 73; 74; 82; 83; 84; 92B; 92C; 92F; 92G; 92H; 92I; 92J; 92K; 92N; 92O; 92P; 93A; 93B; 93C; 93F; 93G; 93H; 93I; 93J; 93K; 93N; 93O; 93P; 94
AreaWashington State; Idaho; Montana; Canada; United States of America
Lat/Long WENS-127.0000 -103.0000 60.0000 48.0000
Subjectstectonics; geophysics; Nature and Environment; Science and Technology; crustal evolution; crustal models; crustal structure; tectonic evolution; sutures; lithosphere; mantle; orogenesis; accretion; craton; tectonic models; plate margins; geophysical surveys; seismic surveys; seismic velocities; anomalies; seismic waves; seismological network; seismic arrays; thermal analyses; Canadian Cordillera; North American Craton; Laurentia; Canadian National Seismograph Network; Canadian Rockies and Alberta Network (CRANE); Canadian Northwest Seismic Experiment (CANOE); Regional Alberta Observatory for Earthquake Studies Network (RAVEN); USArray; Cordilleran Deformation Front; Rocky Mountain Trench; Tintina Fault; Great Slave Lake Shear Zone; Snowbird Tectonic Zone; Trans-Hudson Orogen; Medicine Hat Block; Great Falls Tectonic Zone; Vulcan Structure; Fraser Fault; Hearne Domain; Phanerozoic; Mesozoic; Cretaceous; Precambrian
Illustrationslocation maps; geoscientific sketch maps; schematic cross-sections; geophysical profiles; plots; 3-D diagrams; models
ProgramPublic Safety Geoscience Assessing Earthquake Geohazards
Released2019 05 21
AbstractThe origin of the North American Cordillera and its affinity with the bounding craton are subjects of contentious debate. The mechanisms of orogenesis are rooted in two competing hypotheses known as the accretionary and collisional models. The former model attributes the Cordillera to an archetypal accretionary orogen comprising a collage of exotic terranes. The latter, less popular view argues that the Cordillera is a collisional product between an allochthonous ribbon microcontinent and cratonic North America. Here we present new seismic evidence of a sharp and structurally complex Cordillera-craton boundary in the uppermost mantle beneath the southern Canadian Cordillera, which can be interpreted as either a reshaped craton margin or a Late Cretaceous collisional boundary based on the respective hypotheses. This boundary dips steeply westward underneath a proposed (cryptic) suture in the foreland, consistent with the predicted location and geometry of the mantle suture, thus favoring a collisional origin.
Summary(Plain Language Summary, not published)
Understanding the construction of our continental landmasses has important implications for understanding not only large scale tectonic history, but also for its relevant insights on ongoing processes a present day active plate boundaries. Numerous details on the past construction of the Canadian Cordillera and its relationship with the stable Canadian shield to its east remain uncertain. Unearthing these details will provide insights into the processes we observe at today's active plate boundaries. It has been commonly accepted that the Canadian Cordillera was constructed through an accretionary process where exotic blocks were slowly smeared onto the outboard edge of North America. In contrast, the collisional model, which proposes more energetic events involving the collision of narrow aspect-ratio "ribbon-continents", is somewhat less well adopted, despite evidence in the rock record to support it. In this study, we examined the detailed morphology of the suture between the Canadian Shield and Cordillera deep in the lithospheric mantle using geophysical methods, largely inaccessible to conventional geological techniques. Here we find a deep suture, which is interpreted as a collisional, rather than accretionary feature.

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