摘要
笔者等在研究亚洲位于青藏高原的东、西构造结,和位于中国台湾和日本伊豆地区的构造结以后,发现这4个典型的构造结的地壳上地幔有共同结构:地壳和岩石圈地幔含有上涌的低速异常,而中—下软流圈有集中凸起的高速异常。对这种壳幔结构特征形成的动力学作用机制,提出了以下解释:两组洋—陆或者陆—陆俯冲带运动交叉处相互挤压和撞击,造成比较薄弱的块体的一端破碎。破碎的高的密度大洋岩石圈块体向软流圈下沉,同时使软流圈上层的热流体上涌,最后形成了构造结,同时产生了地震波速上低下高的壳幔结构特征。
After studying the eastern and western tectonic syntaxis in the Qinghai—Xizang(Tibetan)Plateau,and the tectonic syntaxis in the Izu region of Japan and Taiwan,it is found that the upper crustal mantle of these four typical tectonic junctions has a common structure:the crustal and lithospheric mantle contain upwelling lowvelocity anomalies,while the middle and lower asthenosphere have concentrated convex high-velocity anomalies.The following explanations are proposed for the dynamics of the formation of this crust—mantle structural mode:the intersection of the two groups of ocean-to-continent or continent-to-continent subduction zones squeezes and collides with each other,resulting in the fragmentation of end-part of the relatively weak ocean block.The fragmented highdensity oceanic lithospheric blocks sink into the asthenosphere,and at the same time cause the thermal fluid in the upper layer of the asthenosphere to upwell,and finally form a tectonic knot,which also produces the crust—mantle structure characteristics of low and high anomalies of seismic wave velocity.
作者
杨文采
刘晓宇
石战结
瞿辰
YANG Wencai;LIU Xiaoyu;SHI Zhanjie;QU Chen(Zhejiang University,School of Geosciences,Hangzhou,310057;China Geology University(Beijing),Beijing,100083;Institute of Geology,Chines Academy of Geological Sciences,Beijing,100037)
出处
《地质论评》
CAS
CSCD
北大核心
2024年第6期2051-2058,共8页
Geological Review
基金
中国科学院学部咨询评议项目(编号:2022-ZW11-A-0024)的成果。
关键词
构造结
形成机制
地震波速成像
俯冲带交叉
作用模式
tectonic syntaxis
formation mechanism
seismic wave velocity imaging
subduction zone junction
action mode
