沂沭断裂带地壳结构特征:来自远震接收函数的证据

Crustal structure in Yishu fault zone:Evidence from teleseismic receiver functions

沂沭断裂带的地壳厚度和泊松比是理解该区构造演化和深部物质结构的重要依据。本研究收集沂沭断裂带50个固定台站所记录的远震事件数据,应用P波接收函数H-κ叠加扫描方法,分析研究区台站地壳厚度和泊松比特征。结果表明:研究区地壳厚度29.8~35.2 km,平均厚度32.8 km,以沂沭断裂带为界,具有自西北向东南减薄的趋势;泊松比为0.20~0.31,平均0.25,表现出明显的分区特性,位于沂沭断裂带内的台站泊松比明显高于附近地区,该分布特征与研究区的地壳物质组成有关;沂沭断裂带两侧构造单元的地壳结构特征存在明显的差异性,说明沂沭断裂带对不同构造单元具有明显的分割效应。

The distribution of crust thickness and Poisson’s ratio in the Yishu fault zone is an important basis for understanding the tectonic evolution and deep material structure in this area.In this article,the data of teleseismic events recorded by 50 fixed stations in the Yishu fault zone were collected,and the variation characteristics of crustal thickness and Poisson’s ratio of the stations were analyzed by using P-wave receiver functions H-κsuperposition scanning method.The results show that the crust thickness in the study area,ranging from 29.8 to 35.2 km and with an average thickness of 32.8 km,shows a thinning trend from northwest to southeast with the Yishu fault zone as the boundary.The Poisson’s ratio of the study area,ranging from 0.20 to 0.31 and with an average of 0.25,shows obvious zonal characteristics.The Poisson’s ratio of the stations located in the Yishu fault zone is significantly higher than that of the nearby areas,which is closely related to the crustal composition of the study area.There are obvious differences in the crustal structure characteristics of the tectonic units on the two sides of the Yishu fault zone,indicating that the Yishu fault zone has obvious segmentation effect on different tectonic units.