Fault-scale crustal structure across the Dunhua-Mishan fault (Tanlu northern segment) constrained from teleseismic P-wave receiver functions

Abstract

The Dunhua-Mishan fault, located in the northern segment of the Tanlu fault zone, experienced multiple tectonic processes associated with the effects of the Pacific Plate subduction and the Indo-Asia collision. The high-resolution fault-scale structure is critical for understanding the fault evolution and potential fault damage. However, the well-defined deep structure of the Dunhua-Mishan fault is still unclear due to the lack of the dense seismic array. In this study, we construct a high-resolution P-wave receiver function imaging based on linear dense seismic array across the fault. Our results reveal the strong Moho depth variation across the Dunhua-Mishan fault zone. The slightly higher Vp/Vs ratio values within the fault zone indicate the presence of a small amount of mafic crust composition. Interestingly, the significant double positive Ps converted phases are observed within the fault zone, which may represent double Moho discontinuities. The double Moho structure may be related to multiple significant tectonic activities in the Tanlu northern segment. These newly observed structures provide new seismic constraints on the formation and evolution of the Tanlu fault zone and probably reflect that the lithospheric structure of the Dunhua-Mishan fault has been modified by a series of tectonic processes.