摘要
随着探测技术的不断发展,海洋中越来越多的微地块被识别出来,在洋脊增生系统中心、由叠接性洋中脊拓展过程中形成的微小地块,称之为延生微地块(propagation-derived micro-block)。根据其活动状态以及与洋中脊的相对位置,又可划分为在轴型(on-axis)延生微地块和离轴型(off-axis)延生微地块。通过分析位于东太平洋海隆的复活节微地块、胡安·费尔南德斯微地块和纳兹卡板块内部的鲍尔微地块,本文系统总结了延生微地块的识别标志、构造特征及成因模式。延生微地块见于两条洋中脊交汇处或洋中脊与转换断层、海底断裂带交汇处,由捕获自周围大板块的“碎片”、以“碎片”为核心不断增生的洋底物质以及裂谷拓展过程中转移的岩石圈碎片组成。其边界类型有洋中脊或死亡洋中脊、转换断层、大洋汇聚边界、假断层等。延生微地块的成因与洋中脊叠接扩张、拓展延伸息息相关,洋中脊的扩张速率决定了微地块的生长速率。因而扩张速率增大或持续扩张,会促使微地块朝大板块演变;扩张停止,微地块脱离扩张轴,成为离轴型延生微地块,并逐渐融入周围大板块,成为大板块的一部分。
With the development of exploration techniques,more and more micro-blocks in the ocean have been identified.One kind of them is formed at the mid-oceanic ridge and is generated by the propagation of overlapping spreading centers.In this paper,this type of micro-block is called“propagation-derived micro-block”.According to its activity and the position relative to mid-ocean ridge,it can be divided into on-axis and off-axis subtypes.Based on the analysis of the Easter and Juan Fernandez oceanic micro-blocks formed in the East Pacific Rise,and the Bauer micro-block within the Nazca Plate,the identification markers,tectonic characteristics and formation regimes of the propagation-derived micro-blocks are systematically reviewed.This type of micro-blocks is commonly surrounded by several mid-oceanic ridges,or mid-oceanic ridges and transform faults or deep faults,and composed of“lithospheric fragments”captured from the surrounding large-scale plates that exhibits as the core of oceanic accretion.The boundaries of this type micro-blocks include active or fossil mid-oceanic ridge,transform faults,fracture zones,oceanic convergent boundary,pseudo-faults,etc.It is found that the propagation-derived micro-blocks are closely related to the propagating of the overlapping ridge,and the spreading rate of the ridge determines the growth rate of the micro-blocks.Therefore,under the increasing rate or continuous spreading,the micro-block will grow to be a large-scale plate.But,when the spreading stops,the micro-block will break away from the spreading axis and become an off-axis micro-block,which will gradually merge into the surrounding large-scale plate and become a part of it.
作者
赵林涛
李三忠
索艳慧
郭玲莉
王光增
戴黎明
朱俊江
刘博
汪刚
ZHAO Lintao;LI Sanzhong;SUO Yanhui;GUO Lingli;WANG Guangzeng;DAI Liming;ZHU Junjiang;LIU Bo;WANG Gang(Key Lab of Submarine Geosciences and Prospecting Technique,MOE,Institute for Advanced Ocean Study and College of Marine Geosciences,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)
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2019年第4期715-729,共15页
Geotectonica et Metallogenia
基金
“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)
试采海底孔隙压力监测与海洋物理环境研究项目(2018c-03-186)
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联合资助
关键词
微地块
叠接性洋中脊
拓展
洋中脊
旋转
micro-block
overlapping spreading ridge
propagation
mid-ocean ridge
rotation
