HR: 1400h
AN: T43A-05    [Abstracts]
TI: Flexural Modeling of the Andean System Using Finite Element Method
AU: * Sacek, V
EM: victor@iag.usp.br
AU: Ussami, N
EM: nussami@usp.br
AF: São Paulo University, Rua do Matão, 1226, São Paulo, SP 05508900, Brazil
AB: The general equation of flexure of the lithosphere in cartesian coordinates is solved using a numerical Finite Element Method (FEM) with triangular elements in non-structured meshes. This alternative way to model bending of thin elastic plates lying over an inviscid fluid allows taking into account lateral variation of rigidity, plate discontinuities and full 3-D representation of loads. The numerical solution was initially compared with the analytical solution of bending of an elastic plate loaded by an uniformally distributed load. The method was applied to model flexure of a plate due to curved orogenic belts and the results were compared with solutions obtained if a 2-D approximation of plates and loads was considered. The proposed numerical method was applied to study flexural deformation of the western edge of the South American lithospheric plate due to the loads of the Andean mountains, using T_e =75 km for both continuous and broken plates. The predicted forebulges agree with the observed distribution of positive gravity anomalies paralleling the negative gravity anomalies associated with the high topography of the Andes. Maximum amplitudes of forebulges correlate with Purus Arch in Solimões basin (W Brazil) and the Chaco Pampeana plain (Argentina), and between these two regions, a saddle point occurs over the Pantanal wetland (SW Brazil).
DE: 0560 Numerical solutions (4255)
DE: 8138 Lithospheric flexure
SC: Tectonophysics [T]
MN: 2007 Joint Assembly