<span>福建—台湾海峡深部地壳结构探测与滨海断裂带性质研究</span>-华南地震

文章信息/Info

Title:: The Exploration on the Deep Crustal Structure in the Fujian-Western Taiwan Strait and Study on the Littoral Fault Zone

Author(s):: GUO XiaoRan; Xie ZhiZhao; YAN Pei; LI PuChun; WANG Sun; Xiamen Center for Seismic Survey，Earthquake Administration of Fujian Province，Xiamen 361021，China

Keywords:: Deep crustal structure; South China block; Littoral fault zone; Onshore-offshore seismic experiment

摘要:: 基于2012年实施的漳浦—下洋—武平人工地震爆破探测数据以及2015年实施的陆海联测HX07的数据，用射线追踪和正演走时拟合方法，获得了福建南部—台湾海峡的初步二维纵波速度模型。剖面显示：滨海断裂带表现为宽约20 km的切穿地壳的破碎低速带，与其两侧的地壳结构存在较大的横向差异，莫霍面在滨海断裂带处发生较大的突变，其深度由左侧的30 km左右抬升至右侧的28.8 km左右，上下地壳厚度比亦由靠陆一侧的1：1降至向海一侧的0.5：1；上述特征表明滨海断裂带是华南地块正常型陆壳与海区减薄型陆壳的分界断裂。地壳速度在海陆过渡带偏高，康拉德面和莫霍面在此处也有显著抬升，推测其可能是在地壳的伸展拉张及太平洋板块与菲律宾海板块向欧亚大陆板块的俯冲的共同作用下，深部软流圈物质沿着长乐—诏安深大断裂上侵形成的。

Abstract:: Based on the data of the blasting seismic survey line Zhangpu-Xiyang-Wuping in 2012 and the data of Onshore-offshore seismic experiment HX07 carried out in 2015，we got the two-dimensional longitudinal wave velocity model of southern part of Fujian-Taiwan Strait Region. The profile shows that the Littoral Fault Zone manifest as a 20km wide low-velocity fracture zone that cuts through the crust. There is a large lateral difference between crustal structures on both sides of the crust. The Moho has a big mutation at the Littoral Fault Zone. Its depth is raised from about 30km on the left to about 28.8km on the right. The thickness ratio of the upper and lower crusts is also reduced from 1:1 on the land side to 0.5:1 on the seaward side.. The above characteristics show that the Littoral Fault Zone is the boundary fault between the normal continental crust and the thinned continental crust in the South China block. The crustal velocity is high in the transition zone between sea and land, and the Conrad and Moho are also significantly uplifted here. It is speculated that the deep asthenosphere may have formed along the Changle-Zhaoan deep major fault under the joint extension of crustal extension and subduction of Pacific plate and Philippine sea plate to Eurasian plate.