HR: 16:50h
AN: S44A-03 INVITED     [Abstracts]
TI: The crust and lithosphere thicknesses in South America: trying to find the lithosphere- asthenosphere boundary
AU: * Heit, B
EM: heit@gfz-potsdam.de
AF: GFZ-Potsdam, E-226 Telegrafenberg, Potsdam, 14473, Germany
AU: Sodoudi, F
EM: foroug@gfz-potsdam.de
AF: GFZ-Potsdam, E-226 Telegrafenberg, Potsdam, 14473, Germany
AU: Yuan, X
EM: yuan@gfz-potsdam.de
AF: GFZ-Potsdam, E-226 Telegrafenberg, Potsdam, 14473, Germany
AU: Bianchi, M
EM: mbianchi@iag.usp.br
AF: University of Sao Paulo, Departamento de Geofisica University of Sao Paulo, Sao Paulo, Brazil
AU: Kind, R
EM: kind@gfz-potsdam.de
AF: GFZ-Potsdam, E-226 Telegrafenberg, Potsdam, 14473, Germany
AB: During the past years, a series of seismological investigations have been carried out to study the crustal and mantle structures all over the world. In South America, this investigation has not been an easy task as there are different regions where the geodynamics involves the subduction of an oceanic plate, the building of a mountain range as the Andes, the interaction with older lithosphere as the Brazilian Shield and the presence of active deformation fronts between the last two regions. In order to investigate the thickness of the lithosphere in such a complex context we have performed S-wave receiver function analysis (Vinnik and Farra, 2000; Li et al., 2004). The S receiver function technique looks for the S-to-P converted waves at seismic discontinuities beneath a station in the same way as the conventional P receiver function method that deals with P-to-S conversions. The S receiver function technique have proved to be useful to map the Moho and the LAB in many regions where other methods (i.e. surface waves) failed to provide reliable information (e.g. Li et al., 2004; Kumar et al., 2004a, 2004b; Sodoudi et al., 2006). We present here the results of S receiver function technique that has been applied to all the available temporary seismic experiments (e.g. BANJO, SEDA, REFUCA, BLSP) and the permanent stations from the IRIS network. We have been able to investigate the upper mantle discontinuities at all the depths beneath the stations and obtained coherent Moho depths along the entire Andes and in other South American continental regions. The LAB has been clearly detected below some stations, particularly those that are located far away from the subduction zone. By comparing our results with those from the P receiver functions, we have been able to further constrain the thicknesses of the crust and LAB in different regions including shields, mobile belts, basins and mountain ranges. At many stations we have also been able to map the upper mantle discontinuities of the 410 and 660 in South America. The topography of these discontinuities is governed by the temperature in the mantle transition zone and reflects the thermal status of the upper mantle
DE: 7200 SEISMOLOGY
DE: 7218 Lithosphere (1236)
SC: Seismology [S]
MN: 2007 Joint Assembly