洋中脊俯冲的动力学过程  

Dynamics of mid-ocean ridge-involved subduction

作　　者：廖杰 卿佳容 吴扬名 李伦 高锐 Jie Liao;Jiarong Qing;Yangming Wu;Lun Li;Rui Gao(School of Earth Sciences and Engineering,Sun Yat-sen University,Zhuhai 519080,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519080,China;Guangdong Provincial Key Laboratory of Geodynamics and Geohazards,Zhuhai 519080,China;Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention,Institute of Marine Science,Shantou University,Shantou 515063,China)

机构地区：[1]中山大学地球科学与工程学院,珠海519080 [2]南方海洋科学与工程广东省实验室(珠海),珠海519080 [3]广东省地球动力作用与地质灾害重点实验室,珠海519080 [4]汕头大学海洋科学研究院,海洋灾害预警与防护广东省重点实验室,汕头515063

出　　处：《科学通报》2024年第18期2534-2546,共13页Chinese Science Bulletin

基　　金：国家自然科学基金(41974104,42222406,U1901214);广东省“珠江人才计划”引进创新创业团队(2017ZT07Z066)资助。

摘　　要：洋中脊和俯冲带是两个端元的地质构造单元,分别代表离散型和汇聚型的板块边界.但是,二者并不是相互独立的,而是存在强烈的相互作用,如洋中脊以不同形式参与俯冲.我们总结了洋中脊参与俯冲的几种主要形式,即构造环境转变后的洋中脊反转俯冲,汇聚作用下洋中脊与其他构造单元在俯冲启动上的竞争关系,以及洋中脊随俯冲板块输入俯冲带;并概述了与之相关的地球动力学数值模拟,这些研究对理解洋中脊参与俯冲的动力学过程给出了新的认识.(1)在构造汇聚作用下,洋中脊可以反转俯冲;洋中脊的热结构和弱流变强度为俯冲启动提供了重要条件.消亡洋中脊随着温度扩散、强度增加,俯冲难度增大.(2)洋中脊反转俯冲的自然实例相对较少,可能的原因是,与其他洋内及陆缘构造单元(如大洋拆离断层、裂谷型陆缘等)存在竞争关系.模拟揭示了洋中脊与洋内及陆缘构造单元的俯冲竞争关系,并定量阐述了重要物理参数的控制作用.(3)没有形成俯冲带的洋中脊,一个重要归宿是随俯冲板块一并输入到俯冲带.其中,近平行输入和垂直输入是两种端元模式,二者都会影响俯冲过程.洋中脊近平行输入到俯冲带的过程可以用二维模型近似模拟,模拟结果揭示了洋中脊的输入会导致俯冲板块在海沟附近和在板内断离两种形式.洋中脊垂直输入俯冲带可能会导致俯冲板块撕裂并形成板块窗,其动力学过程需要用三维模型系统检验.除了上述介绍的几种洋中脊俯冲过程,更多的洋中脊俯冲模式(如洋中脊倾斜输入俯冲带,洋中脊与转换断层竞争下的俯冲启动)仍需进一步探讨.Mid-ocean ridges and subduction zones are two end-member geological unites,representing divergent and convergent plate boundaries,respectively.These two tectonic units are not isolated in nature,instead,intensive interaction is present between mid-ocean ridges and subduction zones.In this study,we documented a popular way of mid-ocean ridgesubduction interaction,i.e.,subduction with the involve of mid-ocean ridges.We summarized how mid-ocean ridges involve in subduction with particular attention paid on the three possible patterns,i.e.,ridge-inversed subduction under plate compression likely due to the change in plate motion,competition in subduction between mid-ocean ridges and other(intra-oceanic or continental marginal)tectonic units,and the input of mid-ocean ridges into subduction zones.We reviewed the related geodynamical numeric modeling studies that provide new insights on subduction dynamics with the involve of mid-ocean ridges.(1)Ridge-inversed subduction could occur in nature with the possible examples including the Izanagi-Pacific ridge,the Proto South China Sea ridge,the Yap trench,and the Macquarie complex ridge system.Numerical models investigated the dynamics of ridge-inversed subduction under tectonic compression,and revealed that the thermal structure and weak rheological strength of mid-ocean ridges are the key factors.However,subduction through the inversion of extinct mid-ocean ridges becomes difficult,because of its increased strength due to thermal diffusion after the cease of spreading.(2)Natural examples of ridge-inversed subduction are relatively few,and a possible reason is the competition in subduction between mid-ocean ridges and other intra-oceanic or continental marginal tectonic units(e.g.,oceanic detachment fault,transform faults,passive margins)under plate compression.Competition in subduction between mid-ocean ridges and passive margins is investigated in the previous numerical modeling studies,and the key physical parameters affecting the competition in subduction initiation in

关 键 词：洋中脊 俯冲带 洋中脊俯冲 动力学模拟 

分 类 号：P736.1[天文地球—海洋地质]