增生型微地块的成因模式及演化  

Formation Mechanisms and Evolution of Accretion-derived Micro-blocks

作　　者：汪刚[1,2] 李三忠 姜素华[1,2] 索艳慧 郭玲莉[1,2] 朱俊江 王鹏程[1,2] 刘博 WANG Gang;LI Sanzhong;JIANG Suhua;SUO Yanhui;GUO Lingli;ZHU Junjiang;WANG Pengcheng;LIU Bo(Key Lab of Submarine Geosciences and Prospecting Techniques,MOE,Institute for Advanced Ocean Study and College of Marine Geoscience,Ocean University of China,Qingdao 266100,Shandong,China;Laboratory for Marine Geology and Environment,Qingdao National Laboratory for Marine Science and Technology,Qingdao 266237,Shandong,China)

机构地区：[1]海底科学与探测技术教育部重点实验室,中国海洋大学海洋高等研究院和海洋地球科学学院,山东青岛266100 [2]青岛海洋科学与技术国家实验室海洋地质过程与环境功能实验室,山东青岛266237

出　　处：《大地构造与成矿学》2019年第4期745-761,共17页Geotectonica et Metallogenia

基　　金：国家自然科学基金重点项目(91858215);“全球变化与海气相互作用”专项(GASI-GEOGE-01);山东省–国家自然科学基金联合基金(U1606401);国家重点研发项目(2016YFC0601002、2017YFC0601401);中国海洋大学研究生自主科研项目(201861021);青岛海洋科学与技术国家实验室鳌山科技创新计划项目(2016ASKJ13、2017ASKJ02);国家自然科学基金杰出青年基金项目(41325009);山东省泰山学者特聘教授项目;试采海底孔隙压力监测与海洋物理环境研究项目(2018c-03-186)联合资助

摘　　要：增生型微地块是指在俯冲带消亡过程中大?中型洋壳板块内部较厚洋底高原、大火成岩省、外来微地块增生拼贴到大陆边缘而残留形成的微地块。增生型微地块通常位于板块的汇聚地带,其成因是由于俯冲板块上的洋壳高原、海山、岛弧或陆壳到达俯冲带后,因浮力效应增大,使得该微地块的俯冲作用明显地受到阻碍,进而拼贴“停靠”到上覆板块上。例如,西菲律宾海沟的宾汉海隆和马里亚纳海沟北部的小笠原高原,都对俯冲作用产生了极大的阻碍作用并使其近乎停止,这两个高原也得以“停靠”就位在上覆板块边缘。位于中美洲的科伊瓦微板块(Coiba microplate),则由于巴拿马三节点的作用,逐渐与周缘的科科斯板块、纳兹卡板块分离而独立出来,并因其西侧右旋转换型边界和南侧左旋转换型边界的俯冲终止,稳定地“停靠”在中美洲陆缘。总体来说,增生型微板块的边界肯定有一条边为死亡的或活动的俯冲带,其他边界可以是转换型、俯冲型、离散型。转换型边界的实例如菲律宾岛弧带和中美洲的科伊瓦微板块等;俯冲型边界的实例如台湾东部拼贴的北吕宋岛弧;离散型边界的实例主要分布在东南亚?澳洲板块之间的俯冲系统内,这一地区发育了一系列弧后盆地,这些弧后盆地边缘又包含超伸展而裂离的陆壳残块,这一陆壳性质复杂的区域主要是以弧后盆地的扩张中心(离散型边界)和俯冲带作为边界,因而弧后盆地的俯冲消亡很可能会形成新的增生型微板块。The accretion-derived micro-blocks refer to those composed of thick oceanic plateaus,LIPs or allochthonous terranes located in-between tectonic plates/mesoplates,which accreted onto the continental margin of the overriding plate during the convergence along the subduction zone.Therefore,the accretion-derived micro-blocks mostly occur at the convergent margins.Formation of these micro-blocks is mainly triggered by the buoyant oceanic plateaus,volcanic arcs or the splitted continental remnants near trench,which would eventually result in the subduction inhibition or cessation and finally the accretion of micro-blocks onto the overriding plate.For example,the Benham Rise on the western margin of the West Philippine Basin has reached and blocked the Philippine Trench.Moreover,the Ogasawara Plateau on the West Pacific also blocked the Izu-Bonin Trench.Both of them are now docking at the margin of the overriding plate,rejecting subduction down to the mantle.The Coiba microplate in Central America is another typical example.Mostly controlled by the Panama Triple Junction in its West,the Coiba microplate is now relatively independent with its neighbor Cocos and Nazca plates.Depending on the dextral western boundary fault and the sinistral southern boundary fault,the Cobia microplate has successfully stopped its step down to the mantle and docked at the North Panama Trench.In general,as for accretion-derived micro-blocks,one of the boundaries must be a convergent boundary,active or fossil,while the rest can be dominated by transform faults,convergent or divergent boundaries.In accretion-derived microplates such as the Philippine Mobile Belt(PMB)and the Coiba microplate,there are both obvious large transform boundaries like the Philippine Fault and the Panama Fault Zone.But,the North Luzon Arc,which accreted onto the margin of Taiwan,is mainly confined by convergent boundaries.The divergent boundaries often show a spreading center in a back-arc basin,because the spreading center and subduction zone together confine a micro

关 键 词：增生型微地块 增生作用 俯冲作用 三节点 洋底高原 

分 类 号：P542[天文地球—构造地质学] P67[天文地球—地质学]