HR: 17:05h
AN: S44A-04    [Abstracts]
TI: New Moho map for South America from receiver functions and surface waves
AU: * Lloyd, S
EM: simon@earth.northwestern.edu
AF: Department of Earth and Planetary Sciences, Northwestern University, 1850 Campus Drive, Evanston, IL 60208, United States
AU: Van der Lee, S
EM: suzan@earth.northwestern.edu
AF: Department of Earth and Planetary Sciences, Northwestern University, 1850 Campus Drive, Evanston, IL 60208, United States
AU: França, G S
EM: georgesand@unb.br
AF: Observatório Sismológico-IG/UnB, Campus Universitário Darcy Ribeiro SG 13, Asa Norte, 70910-900, Brazil
AU: Asssumpção, M
EM: marcelo@iag.usp.br
AF: Department of Geophysics, IAG, University of São Paulo, Rua do Matão 1226, São Paulo, 05508-090, Brazil
AU: Feng, M
EM: mei_feng_cn@yahoo.com.cn
AF: Institute of Geomechanics, Chinese Academy of Geological Sciences, MinZuDaXueNanLu 11, Beijing, 100081, China
AB: We present new constraints on crustal structure and thickness that we obtained from receiver functions (RF) from 18 temporary seismic stations in Brazil. These stations, of the Brazilian Lithosphere Seismic Project 2002 (BLSP02, Feng et al., 2004), were deployed in seismically inactive regions, previously very sparsely covered with seismic stations. Crustal ages there are predominantly Proterozoic and Archean. We determine crustal thickness and Poisson's ratio from two grid search methods: the commonly used H-k method by Zhu and Kanamori (2000), and the waveform misfit stacking method of Van der Meijde et al. (2003). Combined with approximately 40 receiver functions from other parts of eastern South America our data show no significant correlation between crustal thickness and age. However, our data do suggest that the average Poisson's ratio of the crust increases with decreasing age. The average difference between our results and crustal thickness of Crust2.0 is about 4 km, with some stations differing by as much as 11 km. In order to obtain a continuous sampling, we interpolate crustal thickness estimates from RF analysis between the stations. For this interpolation, we jointly invert the RF point constraints and the surface wave group velocities. We use both the Love and Rayleigh wave group velocities from Feng et al., 2004, which consist of about 6000 Rayleigh-- and 3500 Love wave dispersion curves of good quality.
DE: 7205 Continental crust (1219)
DE: 7218 Lithosphere (1236)
DE: 7270 Tomography (6982, 8180)
DE: 9360 South America
DE: 9619 Precambrian
SC: Seismology [S]
MN: 2007 Joint Assembly