Open AccessShear‐wave velocity in the south‐eastern Brazilian continental shelf
Author(s) -
Souza Jorge Luis
Publication year - 1995
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1995.tb07020.x
Subject(s) - geology , crust , continental shelf , seismology , continental crust , shear (geology) , shear velocity , mantle (geology) , continental margin , geophysics , low velocity zone , shear waves , surface wave , petrology , lithosphere , tectonics , oceanography , turbulence , meteorology , telecommunications , physics , computer science
SUMMARY The crustal structure of the south‐eastern Brazilian continental shelf has been investigated through the dispersion curves of seismic surface waves obtained at Brazilian seismological station RDJ. A set of eight continental‐shelf models has been tried, to obtain the best shear‐wave velocity structure. The inversion results suggest a sedimentary structure divided into two layers with shear‐wave velocities of 1.36 ± 0.10 km s −1 and 1.58 ± 0.10 km s −1 , respectively. This is in agreement with preliminary results found by the Brazilian Petroleum Company Petrobras using seismic data in the area (O. R. Sá & L. P. A. Gamboa, private communication, 1994). The intermediate crustal layer has a shear‐wave velocity (3.26 ± 0.10 km s −1 typical of basement. An anomalous shear‐wave velocity of 3.98 ± 0.10 km s −1 has been determined for the lower crust. This suggests the existence of a transitional layer between lower crust and upper mantle, similar to that observed in both Mediterranean and Canadian passive continental margins. It was not possible to define precisely the crust‐mantle transition, but an analysis of the inversion results has shown that the Moho boundary is at around 40 ± 5 km depth.