洋中脊弯折带的构造-岩浆耦合作用:西北印度洋中脊火山锥及断层分布的约束  

Tectono-magmatic coupling at the bends of mid-ocean ridges: Constraints from volcanic cone and fault distributions along the Northwest Indian Ridge

作　　者：党牛 余星 韩喜球[1,3] 吴招才 邱中炎 王叶剑 李洪林 DANG Niu;YU Xing;HAN XiQiu;WU ZhaoCai;QIU ZhongYan;WANG YeJian;LI HongLin(Key Laboratory of Submarine Geosciences,Second Institute of Oceanography,Ministry of Natural Resources,Hangzhou 310012,China;School of Geography Science,Fujian Normal University,Fuzhou 350007,China;Ocean College,Zhejiang University,Zhoushan 316021,China)

机构地区：[1]自然资源部海底科学重点实验室,自然资源部第二海洋研究所,杭州310012 [2]福建师范大学地理科学学院,福州350007 [3]浙江大学海洋学院,舟山316021

出　　处：《岩石学报》2024年第7期2215-2224,共10页Acta Petrologica Sinica

基　　金：国家重点研发计划(2021YFF0501301);国家自然科学基金项目(42172231、41872242);自然资源部第二海洋研究所基本科研业务费专项(QNRC2202)联合资助。

摘　　要：洋中脊作为全球火山活动最活跃的区域之一,岩浆以裂隙式喷发为主,同时也存在中心式喷发火山锥。本文基于西北印度洋中脊大洋24航次的船载多波束地形数据,选择具有特殊空间位置和构造属性的北部弯折带作为研究靶区,应用定量地貌学方法分析火山锥形态特征与空间分布,探索区域火山作用与构造活动的耦合关系。结果表明,火山锥沿洋脊纵向上的分布主要受控于岩浆供应量,但段内其横向上的分布不仅与岩浆供应量有关,还决定于火山锥岩浆通道的形成。火山锥的分布与断层分布密切相关,断层分布密集,易于火山锥通道的形成。弯折带的洋脊段除了受扩张力外,还受到北东方向的应力作用,使弯折带南翼发育有更密集的断层,更高的火山锥密度。该应力效应的产生与非洲板块的北东向推移、印度板块的逆时针旋转以及弯折带效应本身有关。火山锥形态特征与空间分布,对于理解洋中脊区域构造演化以及火山活动过程具有重要价值。The mid-ocean ridge,dominated by fissure eruptions,is one of the most active volcanic regions in the world,where central eruption volcanic cones also develop.This study focuses on the northern bend of the Northwest Indian Ridge,characterized by its unique spatial location and geological attributes.With the bathymetric data from the DY24 expedition,quantitative geomorphological methods were applied to analyze the morphological features and spatial distribution of volcanic cones,aiming to explore the coupled relationship between regional volcanism and tectonic activity.It shows that the longitudinal distribution of volcanic cones along the ridge is primarily controlled by magma supply,while the lateral distribution within ridge segments is controlled by the formation of the cone magma conduits apart from magma supply.The distribution of volcanic cones is closely related to fault patterns,with dense fault networks facilitating the formation of volcanic cone conduits.The ridge segments of the bend region are subjected to northeast-directed stress in addition to extensional rifting stress,resulting in a denser fault system and higher volcanic cone density on the southern flank than the northern side.The generation of this stress is associated with the northeastward movement of the African Plate,the counterclockwise rotation of the Indian Plate,and the effect of bending itself.Understanding the morphological characteristics and spatial distribution of volcanic cones is of significant value for deciphering the geological and tectonic processes driving volcanic activity in the ridge system.

关 键 词：火山锥 分布特征 构造-岩浆背景 定量地貌学 西北印度洋中脊 

分 类 号：P317[天文地球—固体地球物理学] P542[天文地球—地球物理学]