含水玄武质熔体与方辉橄榄岩反应对克拉通岩石圈演化的约束  

Constraints on the Evolution of the Cratonic Lithosphere from the Reaction of Water-Bearing Basaltic Melts with Harzburgite

作　　者：王孝燕 张行一 李龙曜 王志诚 于博媛 

机构地区：[1]宿州学院资源与土木工程学院,安徽 宿州

出　　处：《自然科学》2021年第5期739-745,共7页Open Journal of Nature Science

摘　　要：克拉通岩石圈在减薄的过程中几乎都发生了性质的改变,在古生代之前华北克拉通的岩石圈地幔主要的岩石类型是方辉橄榄岩,而在中生代以后主要的岩石类型是二辉橄榄岩。在克拉通破坏的过程中,来自软流圈和俯冲板块的玄武质熔体在上升中加热软化岩石圈地幔的同时交代改造岩石圈,但并非所有克拉通岩石圈都会因玄武岩熔体的交代而受到破坏。为了深入了解玄武质熔体交代克拉通岩石圈地幔对认识克拉通型岩石圈地幔演化的意义,在活塞圆筒压机上进行了1100℃/3.0 GPa条件下含水玄武质熔体与方辉橄榄岩的反应实验,模拟了与太平洋板块俯冲有关的岩石圈来源的玄武质熔体交代岩石圈地幔的情景。实验结果显示,克拉通岩石圈交代以后可以从方辉橄榄岩向二辉橄榄岩转化,这与华北克拉通岩石圈中生代的演化趋势一致。因此,太平洋板块俯冲断离造成的含水玄武质熔体上涌可能是造成中生代华北克拉通岩石圈破坏的重要原因之一。The lithosphere of the craton has almost all changed in the process of thinning, and before the Paleozoic Era, the main rock type of the lithospheric mantle of the North China Cratons was harzburgite, while the main rock type after the Mesozoic Era was lherzolite. In the process of craton destruction, basaltic melts from the asthenosphere and subducting plates heat and soften the lithospheric mantle while replacing and reforming the lithosphere, but not all cratonic lithospheres are damaged due to replacement of basaltic melts. In order to understand the significance of replacing cratonic lithospheric mantle by basaltic melts for recognizing the evolution of craton-type lithospheric mantle, we carried out 1100˚C/3.0 GPa water-bearing basaltic melts and harzburgite on a piston cylinder press. The reaction experiment simulates the scenario in which basaltic melts derived from the lithosphere associated with the subduction of the Pacific plate replace the lithospheric mantle. The results show that after replacement, the cratonic lithosphere can be transformed from harzburgite to lherzolite, which is consistent with the Mesozoic evolution trend of the North China cratonic lithosphere. Therefore, the upwelling of water-bearing basaltic melts caused by the subduction and break-off of the Pacific plate may be one of the important reasons for the destruction of the Mesozoic lithosphere in the North China Cratons.

关 键 词：克拉通 高温高压 方辉橄榄岩 玄武质熔体 

分 类 号：P54[天文地球—构造地质学]