板块扩张中心的构造缩短

Tectonic shortening at plate spreading centers

洋中脊是地球上重要的火山-地震带之一,也是多圈层相互作用以及能量和物质交换的重要构造位置。洋中脊作为板块构造理论中典型的离散板块边界,伸展构造以及与其相关的正断层活动是其变形的主旋律。然而,2022年年底北大西洋54ºN段发生了一次逆冲断层地震活动。文章主要报道并简述与这次地震事件相关的且发表在2024年4月Nature期刊上的一篇研究论文。该论文通过地震观测、地质分析及数值模拟等多学科综合研究,详细报道了在典型离散板块边界发生的逆冲地震活动,深入分析了短时间尺度内地震事件在海底地貌上的记录,并对伸展构造背景下挤压应力区的发育机制进行了论证。以上研究挑战了离散板块边界只发育伸展构造的传统观点,也证实了多学科综合作业以及多时间尺度地质过程耦合分析等手段对开展固体地球科学研究的必要性。

The mid-ocean ridge is a remarkable feature of our planet,renowned as one of Earth's most vital zones for volcanic and seismic activity.It serves as a crucial setting for the transfer of energy and materials be-tween the ocean and lithosphere.As the archetypal divergent plate boundary,mid-ocean ridges are primarily sculpted by extensional tectonics and the associated development of normal faults.However,in a surprising twist,a thrust seismic event was detected in late 2022 along the 54ºN segment of the Atlantic mid-ocean ridge.This arti-cle focuses on summarizing a recent paper that addresses this seismic event,featured in the prestigious journal Na-ture(https://www.nature.com/articles/s41586-024-07247-w).The research,integrating seismic observations,geo-logical analyses,and numerical simulations across multiple disciplines,provides a detailed account of the thrust seismic activity at a classical divergent plate boundary.It delves into the imprint of these short-lived seismic events on the landscape's topography and geomorphology,elucidating the mechanisms behind the formation of compression stress zones within an extensional tectonic setting.The study not only challenges the long-held as-sumption that divergent plate boundaries are solely associated with extensional tectonics but also underscores the indispensable role of interdisciplinary collaboration and the integration of geological processes across different timescales in advancing solid Earth science research.