东非肯尼亚裂谷内地裂缝的多层级结构和成因机制  

Multi-level structure and formation mechanism of ground fissures in the Kenya Rift Valley,East Africa

作　　者：贾智杰 卢全中[1,2] 黄伟亮[1,2] 庄建琦[1,2] 朱兴华[1,2] 马鹏辉 王飞永[3] 王祚鹏 刘阳 贺鸣 赵俊彦 何芝远 霍秉尧 彭建兵 JIA Zhijie;LU Quanzhong;HUANG Weiliang;ZHUANG Jianqi;ZHU Xinghua;MA Penghui;WANG Feiyong;WANG Zuopeng;LIU Yang;HE Ming;ZHAO Junyan;HE Zhiyuan;HUO Bingyao;PENG Jianbing(School of Geological Engineering and Surveying,Chang'an University,Xi'an,Shaanxi 710061,China;Key Laboratory of Western Mineral Resources and Geological Engineering of Ministry of Education,Chang'an University,Xi'an,Shaanxi 710061,China;School of Engineering and Technology,China University of Geosciences(Beijing),Beijing 100083,China)

机构地区：[1]长安大学地质工程与测绘学院,陕西西安710061 [2]长安大学西部矿产资源与地质工程教育部重点实验室,陕西西安710061 [3]中国地质大学(北京)工程技术学院,北京100083

出　　处：《地质学报》2025年第3期719-732,共14页Acta Geologica Sinica

基　　金：国家自然科学基金国际(地区)合作与交流项目(编号41920104010);自然资源部地裂缝地质灾害重点实验室开放基金项目(编号EFGD20240609)联合资助的成果。

摘　　要：东非大裂谷作为地球最著名的大陆裂谷和断陷带,开展裂谷内的地裂缝成因研究对理解主动裂谷作用以及指导裂谷区工程建设具有重要意义。本文在对东非肯尼亚裂谷地裂缝进行野外调查,槽探,地球物理勘探以及氦同位素检测的基础上,建立了地裂缝在地壳内的多层级结构,并分析了其成因机制。结果表明:研究区共发育22条大型地裂缝,地裂缝主要分布于研究区的东侧边界断裂与两座火山之间的裂谷盆地内。地裂缝在地表表现为松散沉积物的破裂塌陷,在火山碎屑岩表面显示为单纯的拉张裂缝并具有冒气现象,电阻率探测表明地裂缝是地壳内岩石裂隙在浅表部的延伸。结合氦同位素特征,揭示了地裂缝—基岩破裂—断层—岩浆房—断层—上地幔组成的地裂缝壳-幔-岩石圈多层级结构。在以上研究基础上,根据研究区地壳形变特征和数值模拟,揭示了东非肯尼亚地裂缝的成因机制并总结为:地幔上涌—地幔入侵—岩浆房膨胀—地表成缝。The East African Rift System,as the most famous continental rift and fault zone on Earth,conducts research on the formation of ground fissures within the rift valley,which is of great significance for understanding the active rift process and guiding the engineering construction of the rift valley area.Based on field investigations,trenching,geophysical exploration,and helium isotope detection of ground fissures in the Kenya Rift Valley,East Africa,this article establishes a multi-level structure of ground fissures in the crust and analyzes their formation mechanisms.The results indicate that the study area has a total of 22 large ground fissures,mainly distributed in the rift basin between the eastern boundary fault and two volcanoes.These ground fissures appear on the surface as ruptures and collapses of loose sediments,as well as simple tensile fractures with degassing on the surface of pyroclastic rocks.Resistivity detection shows that ground fissures are extensions of rock fissures in the crust.Based on the characteristics of helium isotopes,a multi-level structure consisting of ground fissures,rock fractures,faults,magma chambers,and the upper mantle has been revealed.Based on this research,combined with the characteristics of crustal deformation and numerical simulation,the formation mechanism of ground fissures in the Kenya Rift Valley can be summarized as follows:mantle upwelling,mantle intrusion,magma chamber expansion,and surface fracturing.

关 键 词：东非大裂谷 地裂缝 地幔柱 板块伸展 成因机制 

分 类 号：P61[天文地球—矿床学]