Remnants of the Amalgamation of the East and West Cathaysia Blocks Revealed by a Short-period Dense Seismic Array

Abstract

To better constrain the amalgamation of the East and West Cathaysia blocks, we deployed a short-period dense seismic array oriented nearly north-south in the southwestern Cathaysia block. According to the 997 teleseismic receiver functions recorded by 527 node geophones, we find that the Mohorovicic discontinuity (Moho) is slightly uplifted towards the coastal Cathaysia block. The most obvious feature is the high Vp/Vs ratio and deepen Moho beneath the Sanshui basin. Based on the common conversion point (CCP) migration images, we deduce that there may be distributed with the extension of the Gaoyao-Huilai deep fault, and it is supported by the offset of Moho and occurrence of the Mw 4.3 earthquake. Combined with other evidences, we further concluded that a weak suture zone is constrained beneath along the Zhenghe-Dapu and Gaoyao-Huilai deep faults, which may indicate the remnants of the amalgamation of the East and West Cathaysia blocks.