近日，美国哥伦比亚大学Brandon Shuck团队研究了转换构造驱动下的板块撕裂和分段俯冲终止。这一研究成果于2025年9月26日发表在《科学进展》杂志上。
当洋中脊靠近海沟时，俯冲可能终止，引入浮力岩石圈，抵制俯冲，导致板块分离和板块边界重构。然而，由于缺乏现代的例子，板坯撕裂的时空动力学仍然是一个谜。
近日，研究组将新的地震图像与区域地震活动相结合，研究了卡斯卡迪亚北部脊-沟-断层三重交界处的一个主动破碎的俯冲系统，那里的俯冲即将结束。他们的分析揭示了一个广泛的剪切带，起源于~4 Ma，利用了新生海洋岩石圈的脊-平行构造，并逐渐定位为成熟的沟-垂直转换边界。这一过程切断了一个海洋微板块，使其相对于邻近的俯冲岩石圈的俯冲减弱。
在俯冲区域，研究组成像了与沟平行的板块撕裂被转换抵消，表明侧向撕裂传播被转换边界相交，促进了微板块的有效解耦，同时允许相邻的俯冲继续进行。研究组提出了一个四维模型，其中转换边界驱动横向历时板块破碎和俯冲终止。
附：英文原文
Title: Slab tearing and segmented subduction termination driven by transform tectonics
Author: Brandon Shuck, Brian Boston, Suzanne M. Carbotte, Shuoshuo Han, Anne Bécel, Nathaniel C. Miller, J. Pablo Canales, Jesse Hutchinson, Reid Merrill, Jeffrey Beeson, Pinar Gurun, Geena Littel, Mladen R. Nedimovi, Genevieve Savard, Harold Tobin
Issue&Volume: 2025-09-26
Abstract: Subduction may terminate when a mid-ocean ridge approaches a trench, introducing buoyant lithosphere that resists subduction, leading to slab detachment and plate boundary reconfiguration. Yet, the spatial and temporal dynamics of slab tearing remain enigmatic due to a lack of modern examples. Here, we integrate new seismic images with regional seismicity to investigate an actively fragmenting subduction system at northern Cascadia’s ridge-trench-fault triple junction where subduction termination is imminent. Our analyses reveal a broad shear-zone initiated at ~4 Ma by exploiting ridge-parallel fabrics of nascent oceanic lithosphere and progressively localized into a mature trench-perpendicular transform boundary. This process severed an oceanic microplate and enabled its diminished subduction relative to adjacent subducting lithosphere. Downdip, we image trench-parallel slab tears offset by the transform, suggesting lateral tear propagation was intersected by the transform boundary, facilitating efficient decoupling of the microplate while allowing adjacent subduction to continue. We propose a 4D model where transform boundaries drive laterally diachronous slab fragmentation and subduction termination.
DOI: ady8347
Source: https://www.science.org/doi/10.1126/sciadv.ady8347