Surface wave imaging using deep reflection seismic data: a study on the Cuonadong dome

Abstract

As interference waves in deep reflection data processing, surface waves are often suppressed as noise, but surface waves carry considerable underground media information, including structural information and the physical properties of rocks. Reasonable extraction and use of surface wave signals are of great significance when studying shallow characteristics. Deep reflection data are collected using large offsets, trail spacing, and explosive sources. The surface wave energy tends to be stronger, and the high-frequency surface wave signal is abundant. After extraction and inversion, the shallow shear wave velocity structure can be obtained. Near the Cuonadong dome in the southern Tibetan detachment system (STDS), a large number of leucogranites are developed in the core, containing important rare metal minerals and high metallogenic potential. However, studies regarding the shallow structure in this region are rare. In this paper, we use deep reflection data from a profile through the Cuonadong dome to obtain the S-wave velocity structure of the study area by extracting the surface wave fundamental-mode dispersion curve and inversion. Combined with regional geological and magnetotelluric data, we supposed that the thickness of the Cuonadong dome sediment layer (< 1.4 km/s) varies greatly from east to west, the thickness of the sediment layer is the deepest near the Cuona fault and Jisong fault (more than 1 km), and the core of the dome is the thinnest. Under the Cuonadong dome, there are obvious high-velocity anomalies (> 2.2 km/s), and the horizontal S-wave velocity changes greatly, which is mainly related to the destruction of magmatic activity since the Miocene. These understandings of the structure and velocity field of the Cuonadong dome can provide a powerful geophysical basis for establishing the dome structure model and searching for hidden ore bodies.Graphical abstract