中国科学院地质与地球物理研究所万博团队研究了奥林匹克造山带的塑性修复及其意义。相关论文发表在2025年7月8日出版的《地质学》杂志上。

奥林匹克山脉的地形颗粒和基岩结构在卡斯卡迪亚俯冲带上部板块的地图视图中定义了一个向陆地凸起的马蹄形（奥林匹克造山带）。该图曲率被解释为造山带/海沟因吸积和底侵而正常变形的产物。Siletzia地体的玄武质新月形地层在奥林匹克山脉外围露头，并继续向南延伸，位于“俄勒冈州弧前地块”的大部分下方。区域GPS和古地磁研究表明，奥林匹克造山带的分支在相对于克拉通北美的整体向北运动中记录了相反的旋转。 

研究组汇编了古地磁和构造数据，表明奥林匹克造山带是一个垂直轴褶皱。他们重新发现了褶皱，表明造山褶皱容纳了卡斯卡迪亚前弧110公里的缩短。他们认为俯冲逆冲最初产生了一个边缘平行的、向海的边缘褶皱带。造山褶皱是由变形的、向北平移的前弧钉靠在北部的海岸山脉扶壁上造成的。上板块的造山带弯曲导致铰链带向陆地退缩，远离海沟，导致生长的造山带下方向下的Juan de Fuca海洋岩石圈被动向上翘曲。该模型提供了一个变形序列，解释了卡斯卡迪亚前弧边缘平行平移和缩短导致的奥林匹克山脉。

附：英文原文

Title: Palinspastic restoration of the Olympic orocline and its implications

Author: Wenbo Zhang, Stephen T. Johnston, Kristin Morell, Bo Wan

Issue&Volume: 2025-07-08

Abstract: The topographic grain and bedrock structure of the Olympic Mountains define a convex-landward horseshoe shape in map view (the Olympic orocline) in the upper plate of the Cascadia subduction zone. This map curvature has been explained as a product of orogen/trench-normal deformation due to accretion and underplating. The basaltic Crescent Formation of the Siletzia terrane outcrops around the periphery of the Olympic Mountains and continues south, underlying much of the “Oregon forearc block.” Regional GPS and paleomagnetic studies demonstrate that the limbs of the Olympic orocline record opposite rotations during overall northward motion relative to cratonic North America. Here, we compile paleomagnetic and structural data to show that the Olympic orocline is a vertical-axis fold. We palinspastically undo the fold, showing that oroclinal folding accommodated 110 km of shortening of the Cascadia forearc. We suggest that subduction underthrusting initially produced a margin-parallel, oceanward-verging fold belt. Oroclinal folding resulted from pinning of the deformed, northward-translating forearc against the Coast Range buttress to the north. Oroclinal bending of the upper plate resulted in the landward retreat of the hinge zone away from the trench, giving rise to passive upward warping of the downgoing Juan de Fuca oceanic lithosphere beneath the growing orocline. Our model provides a deformation sequence that explains the Olympic Mountains as a result of margin-parallel translation and shortening of the Cascadia forearc.

DOI: 10.1130/G53365.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G53365.1/659435/Palinspastic-restoration-of-the-Olympic-oroclineredirectedFrom=fulltext