岩石圈长波长磁异常及其地质意义  

Lithospheric long-wavelength magnetic anomalies and their geological origins:A review

作　　者：王婕 杨艳艳 纪飞 罗钰馨 泽仁志玛 黄建平 申旭辉 Wang Jie;Yang Yanyan;Ji Fei;Luo Yuxin;Zeren Zhima;Huang Jianping;Shen Xuhui(National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China;School of Emergency Management Science and Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;National Space Science Center,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]应急管理部国家自然灾害防治研究院,北京100085 [2]中国科学院大学应急管理科学与工程学院,北京100049 [3]中国科学院国家空间科学中心,北京100190

出　　处：《地球与行星物理论评（中英文）》2024年第6期668-680,共13页Reviews of Geophysics and Planetary Physics

基　　金：国家自然科学基金青年基金资助项目(42004051);国家自然科学基金资助项目(42274214)。

摘　　要：在低轨卫星几百千米的高度上,大部分近地表观测到的岩石圈磁异常细节衰减殆尽,只留下衰减较慢的长波长磁异常.长波长磁异常可以揭示出岩石圈居里面以上显著的物性差异,对于研究地壳深部的物质组成、结构和演化具有重要意义.为了使读者能从全球尺度上对长波长磁异常的起源形成具体的认识,本文首先回顾了不同时期的卫星磁异常图及主要的岩石圈磁场模型,然后基于CHAOS-7模型计算结果,对500 km高度除极区外幅值大于4 nT的长波长磁异常进行了识别编号,共计29个磁异常.其中,陆地上磁异常20个,海洋中磁异常9个.通过对已有研究成果的综述及地质资料的对比分析,逐一介绍了磁异常的起源.陆地区域的长波长磁异常大多位于前寒武基底,相关的地质单元有太古代地核、元古代地体、富铁建造等,少数位于造山带背景.海洋区域的长波长磁异常全部都位于洋底高原,普遍与白垩纪时期冈瓦纳大陆裂解相关,具有加厚地壳特征.因此,针对长波长磁异常的持续深入研究对于地壳生长和演化具有重要意义.随着我国卫星磁测的蓬勃发展,相信会有越来越多的国内科研人员关注并研究这类大规模磁异常.At the altitude of low-Earth-orbiting satellites,most details of lithospheric magnetic anomalies observed near surface are attenuated,and only slowly decaying long-wavelength magnetic anomalies can be detected.Long-wavelength magnetic anomalies are generated by large-scale magnetized rocks in the Earth's crust and uppermost mantle at depths shallower than the Curie depth.Interpretation of such lithospheric magnetic anomalies has been used in geological mapping,crustal composition and structure studies,plate tectonic reconstruction,and geodynamics.To introduce the origin of long-wavelength magnetic anomalies at a global scale,we first reviewed satellite magnetic anomaly maps in early periods and calculated anomaly maps using four main lithospheric magnetic field models,including the CHAOS-7,CM6,MF7,and CSES models.Then,based on the result of the CHAOS-7 model at 500 km altitude,29 long-wavelength magnetic anomalies with amplitudes greater than 4 nT were identified and their geological origins were reviewed.Among these,there were twenty magnetic anomalies over conti-nents and nine over the ocean.The long-wavelength magnetic anomalies over continental areas were mostly loc-ated in Precambrian basements related to the Archean nuclei,Proterozoic terrane,and iron-rich formations,with a few located in the orogenic background.The long-wavelength magnetic anomalies in the ocean region were all loc-ated in oceanic plateau,generally related to the breakup of Gondwana during the Cretaceous Period,and have the characteristics of thickened crust.Hence,the long-wavelength magnetic anomalies reveal a significant magnetiza-tion difference in the deep crust during crustal growth,a key issue that requires further study.Compared to satellite magnetic surveys in some other nations,detecting lithospheric magnetic anomalies by satellite started relatively late in China.The China Seismo-Electromagnetic Satellite(CSES)was launched in February 2018.It was China's first satellite designed to monitor earthquakes with multiple geophysical pa

关 键 词：长波长磁异常 卫星磁测 岩石圈磁异常 前寒武基底 洋底高原 

分 类 号：P318[天文地球—固体地球物理学]