Crustal and uppermost mantle structure beneath Lei-Qiong region constrained by ambient noise tomography
Abstract
The region of Leizhou Peninsula and Hainan Island in Southern China, or Lei-Qiong for short, has seen extensive volcanic activities since late Cenozoic. Several lines of evidence from geophysics and geochemistry indicate the Hainan mantle plume, which likely originates from the lower mantle, is responsible for the large-flux, intraplate volcanisms in this region. However, the interactions between the rising mantle materials and the overlaying plate, in particular how surface volcanos connect with their deep roots in the shallow lithosphere, remain obscure due to limitations of data and resolution in previous studies.
In this study, we present a S-wave velocity model of crust and uppermost mantle derived from the ambient noise tomography for Lei-Qiong region. We use seismic data recorded at 42 local broadband stations for over a 3-year period (2016-2018). We invert Rayleigh wave phase velocity dispersion curves from ambient noise interferometry for 3 -D heterogeneity and azimuthal anisotropy in the shallow lithosphere. We found a large low-velocity body within the crust beneath recently active volcanos near Haikou. Based on the lateral variation of S-wave velocity and the azimuthal anisotropy, we mapped a relatively low-velocity zone, which we interpret it as the magma-containing zone in the uppermost mantle.In addition, local Moho deepening corresponds well with the lowest velocity zone, suggesting the presence of underplating beneath the pre-existing crust.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.S11D0362P
- Keywords:
-
- 7212 Earthquake ground motions and engineering seismology;
- SEISMOLOGY;
- 7219 Seismic monitoring and test-ban treaty verification;
- SEISMOLOGY;
- 7255 Surface waves and free oscillations;
- SEISMOLOGY;
- 7270 Tomography;
- SEISMOLOGY