The 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, consisent with the predicted location and geometry of the mantle suture, thus favoring a collisional origin.

中文翻译：

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地幔缝合的地震证据及其对加拿大山脉的起源的影响。

北美山脉的起源及其与边界克拉通的亲和力是有争议的话题。造山运动的机理源于两个相互竞争的假设，即增生模型和碰撞模型。以前的模型将Cordillera归​​因于原型增生造山带，其中包括外来地形的拼贴。后者（较不受欢迎）认为科迪勒拉是异源带状微大陆与北美洲克拉通之间的碰撞产物。在这里，我们提供了新的地震证据，表明加拿大南部山脉下方最上层地幔中的尖锐且结构复杂的科尔迪勒克拉通边界，根据各自的假设，可以解释为克拉通边缘重塑或白垩纪晚期碰撞边界。