Imaging Poisson ratio of uppermost mantle beneath China
Abstract
We have obtained a Poisson's ratio image of the uppermost mantle beneath China by performing tomographic inversion of travel time differences between Sn and Pn. The arrival pairs were selected from the Annual Bulletin of Chinese Earthquakes from 1984 to 2007. The dataset includes 50,136 arrival pairs from 11,470 earthquakes recorded by 116 stations. The average Poisson's ratio is 0.26. The preliminary tomographic results show that 1) the Poisson's ratio is low in the stable cratons around the Tibetan Plateau such as the Tarim and Junggar basins, the Ordos craton, and the southern region of the Sichuan basin; and 2) the Poisson's ratio is high in the entire Tibetan Plateau, the North-South Seismic Zone, and North China; and 3) the high Poisson's ratio region in the Tibetan Plateau extends to the surrounding cratons, suggesting that a) the uplift of Tibetan Plateau results from a high Poisson's ratio or partially melted rocks beneath the plateau, and b) the soft rocks intruded into the bottom of surrounding cratons.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.T13B1946C
- Keywords:
-
- 7218 Lithosphere (1236);
- 8180 Tomography (6982;
- 7270)