Seamounts are ubiquitous on the oceanic plate; those situated near convergent margins will eventually undergo subduction. Using six prestack depth migrated MCS profiles transecting the Aleutian Trench, we investigate deeply buried seamounts offshore Kodiak Island, within 145–155°W and 55–58°N. A distinct sedimentary horizon exists in all six seismic profiles, at or above the average height of seamounts, which appears to be the preferred structural detachment zone. Where drilled, this horizon contains gravel‐sized debris interpreted to be ice rafted and marks the onset of intensification of Northern Hemisphere glaciation at ~2.7 Ma. Beneath this horizon, sediments prior to the Surveyor Fan development were deposited, all or the majority of these sediments will eventually be subducted. Despite the subducted seamounts being deeply buried, these features cause enhanced surface slope of the accretionary prism. Our observations lead us to propose a model for the stages of subduction for deeply buried seamounts. These stages include the following: (1) Prior to subduction, the protothrust zone undergoes enhanced shortening, (2) frontal thrust steepening and enhanced backthrusting occurs during subduction with a potential décollement step down seaward and a steeping outward of the deformation front to the limit of the protothrust zone, and (3) further subduction results in a pattern of uplift farther into the wedge resulting in enhanced out‐of‐sequence thrusting and persistence of the more seaward deformation front position. This pattern is distinct from the dominance of embayments and effective removal of prism material during seamount subduction described along margins with less deeply buried edifices.

中文翻译：

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对科迪亚克岛近海深埋海山俯冲的影响

海山遍及大洋板块。那些位于趋同边缘的最终将被俯冲。我们使用六个穿越阿留申海沟的叠前深度偏移的MCS剖面，研究了Wed 145-155°W和N-55°N范围内科迪亚克岛近海的深埋海山。在全部六个地震剖面中，在海山的平均高度或以上，存在明显的沉积层位，这似乎是首选的结构分离带。在钻探的地方，该地平线包含砾石大小的碎屑，这些碎屑被认为是漂流的，标志着北半球冰川在2.7 Ma时开始加剧。在此地平线之下，在验船师范开发之前沉积了沉积物，所有或大部分这些沉积物最终将被俯冲。尽管俯冲的海山被深深掩埋，这些特征会导致增生棱镜的表面倾斜度增加。我们的观察使我们为深埋海山的俯冲阶段提出了一个模型。这些阶段包括：（1）俯冲前，原俯冲带经历了缩短的缩短，（2）俯冲过程中，前推力陡峭和反冲增强，潜在的俯折作用向海下倾斜，并且变形前缘向外陡峭到极限（3）进一步的俯冲作用导致进一步向楔块隆起的模式，导致乱序推力增强，并且向海变形前沿位置持续存在。