Abstract The Pacific Northwest has undergone extensive tectonic and magmatic construction in the Cenozoic, and many clues to its history are in a well-resolved upper mantle structure. We present new P, S, and V P / V S models that benefit from improved algorithms and additional data from recently deployed flexible array experiments in the region of the Columbia River Basalts, western Snake River Plain, and Idaho Batholith. We refine the geometries of previously imaged structures and identify new anomalies beneath the Pacific Northwest. A clear separation is resolved between the Wallowa and Idaho structures that extends from the base of the crust to the depth extent of these structures. The separation follows the Precambrian margin of North America, possibly indicating separate tectonic histories for the two structures. A shallow fast anomaly beneath Idaho Batholith may be responsible for the observed curvature of the Yellowstone track around this batholith. And a strong and unusually deep (180–250 km) slow anomaly is present east of the apparent Juan de Fuca slab gap. Resolving these structures well is important in understanding the origin of the lithospheric fragments in the mantle, and key to any reconstruction of the evolution of the Pacific Northwest-Farallon-Kula-Juan de Fuca tectonic system. Of most relevance, understanding the origin of the imaged high-velocity mantle structures provides strong constraint on their density, that otherwise would be largely unknown, which controls the evolution of vertical and horizontal stresses acting at the base of the lithosphere and hence the evolution of topography. Also, resolving the volumes of partially molten upper mantle shapes our understanding on the origin of the abundant volcanism in the Pacific Northwest interior.

中文翻译：

---

太平洋西北地区内陆下的上地幔断层扫描

摘要 太平洋西北地区在新生代经历了广泛的构造和岩浆构造，其历史的许多线索都在一个得到很好解析的上地幔结构中。我们展示了新的 P、S 和 VP / VS 模型，这些模型受益于改进的算法和最近在哥伦比亚河玄武岩、蛇河平原西部和爱达荷州基石地区部署的灵活阵列实验的附加数据。我们改进了先前成像结构的几何形状，并确定了太平洋西北部下方的新异常。从地壳底部延伸到这些结构的深度范围的 Wallowa 和 Idaho 结构之间的清晰分离得到解决。分离遵循北美的前寒武纪边缘，可能表明这两个结构的构造历史不同。爱达荷州基石下方的浅层快速异常可能是观测到的黄石轨道围绕该基石弯曲的原因。在明显的胡安德富卡板块间隙以东存在强烈且异常深（180-250 公里）的缓慢异常。很好地解析这些结构对于了解地幔中岩石圈碎片的起源很重要，也是重建太平洋西北-法拉隆-库拉-胡安德富卡构造系统演化的关键。最相关的是，了解成像的高速地幔结构的起源对其密度提供了强有力的约束，否则在很大程度上是未知的，它控制作用在岩石圈底部的垂直和水平应力的演化，从而控制作用于岩石圈底部的垂直和水平应力的演化。地形。还，