Some methods used to determinate the boundary between continental and oceanic crust in the argentine volcanic passive margin.

ABRAHAM, D. A.; GHIDELA, M.; TASSONE, A; PATERLINI, M.; ANCAROLA, M.

Buenos Aires

Workshop; Giambiaggi School- Applied and Enviromental Geophysics; 2012

FCEyN. Dpto. Física

The region of the continental margin passive volcanic Argentine between 46 ° S and 35 ° S is characterized by the presence of major volcanic wedges in the transition zone between continental crust and oceanic crust. In the seismic reflection, wedges are recorded as seismic seaward reflectors. This work was a study on the top of the basement interpreted in seismic sections using the short Fourier transform (spectral method) to calculate the density of spectral energy of the signal. Once identified spatially wave numbers corresponding to local maxima of spectral energy density, became a filtering of the signal with a pass band filter. The filter was built with spatial frequencies identified in the area corresponding to oceanic crust. The range of wavelengths obtained in the area of transitional crust and oceanic was between 4 km and 6 km approximately. We calculated the standard deviation of the residuals between the signal of the top of the basement and the linear fit on sections of two kilometers of length approximately to characterize the roughness (statistical method). We found that the spatial frequency determined by the spectral method and the roughness calculated with the statistical method are good indicators of the beginning of the oceanic crust in the studied region, noting further that the positions obtained were compared with the seafloor spreading magnetic anomalies of the M series identified in the region of study on oceanic crust.